Programmer`s Guide and Reference

Programmer`s Guide and Reference
Programmer’s Guide and Reference
BACtalk Systems
© Honeywell
LTBT-TM-PRGRMR Rev. 13
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© Honeywell
Contents
Contents
Chapter 1: About BACnet, BACtalk, and DDC
About BACnet
About BACtalk
BACtalk controllers
About DDC programming environments
VisualLogic
DDC editors
Understanding VLC DDC in the BACnet environment
Storage of values in C3-series VLCs
Storage of values in Gen4 VLCs
RAM space limitations for certain VLC DDC functions
Chapter 2: Identifying and using system data
Inputs and outputs (AIs, AOs, BIs, BOs)
Values (AVs and BVs)
Multistate objects (MIs, MOs, and MVs)
Special point types available in DDC
Using NOT and REV on function inputs and outputs
Priority arrays
Subroutine DDC
Chapter 3: The VisualLogic development environment
Installing and using Visio
Using VisualLogic
About the VisualLogic Toolkit
Features
Best practices
Using shortcut keys
About DDC and drawing files
Creating and opening VisualLogic and DDC files
Setting program information
Setting options
Saving your work
Selecting a format
Selecting elements to save
Saving your work as a Visio drawing
Saving your work as DDC
Saving a .bd4 DDC file in a .bd6 DDC format
Sending DDC to a device
Sending an open DDC file to a device
Sending a DDC file from disk to device
Setting up VLCs and Advanced VLCs with VisualLogic
About the Device Settings dialog box
Setting program units
Selecting description sets
Disabling Microset auto-detection
Protecting the DDC file
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Setting the DDC execution speed (Advanced VLC only)
Importing or exporting DDC data to an Excel worksheet
Importing
Exporting
Setting point descriptions
Setting up analog inputs (AIs)
Setting up analog outputs (AOs)
Setting up binary outputs (BOs)
Setting up analog values (AVs)
Setting up multistate values (MVs) (Advanced VLCs only)
Setting up Microset field service codes
Authoring DDC in VisualLogic
Working with VisualLogic design tools
Adding functions to your drawing from the stencil
Setting inputs, outputs, and other function parameters
Linking functions with connectors
Propagating function parameters
Automatically
Manually
Repeating functions
Resequencing functions
Cross-referencing functions
Comparing drawings
Straighten connector functions
Wrap Descriptor
Creating program comments and generating a
sequence of operations
Searching for an element
Viewing DDC statistics
Checking your drawing and viewing errors and warnings
Viewing live data
Steps
Considerations
Setting VisualLogic Toolkit defaults
Chapter 4: Programming VLC DDC for the BACtalk Microset and Microtouch
About the Microset
About the Microtouch
Analog and binary values assigned to Microset and
Microtouch operation
Setpoint calculation
Microtouch offsets
Occupied and unoccupied modes
After-hours operation
Typical DDC for a Microset
Field Service mode (MS-10xx)
Balance mode (MS-10xx)
Chapter 5: Programming techniques and strategies
Useful tips
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Include Function 1: END OF NORMAL SEQUENCE
Write separate DDC programs for devices on
different networks
Do not write to a data point more than once
Leave room to grow
Plan before you program
Document meticulously
Save your DDC
Test before equipment startup
Use peer-to-peer DDC functions sparingly
DDC download and start up
Assign all connections
Integrating with other applications using automation
Using DDC to detect VLC communications failure
Method 1
Method 2
Method 3 (alternative)
Using DDC to detect communications failure in a global
controller (C3 VLCs only)
Explanation of DDC
Global controller DDC sequence
VLC DDC sequence
Resolution of Microset-related AVs and use in DDC
Understanding BACtalk PI and PID functions
What is PID control?
PI versus PID
How is the output of the PI function calculated?
Reversing the output for reverse acting applications
Setting the tuning parameters
Proportional constant (Kp)
Integral constant (Ki)
Maximum integral change (Imax)
Integral limit (Ilimit)
Integral startup (STUP)
Proportional constant versus throttling range
Bit-packer and bit-unpacker DDC
Bit-packer DDC routine
Bit-unpacker DDC routine
Migrating IBEX global controller DDC to the BCM-TUX
Dedicate BCM-TUX programming to connected TUXs
No TUX DDC editing capability from a BACtalk system
IBEX control strategies compared to BCM-TUX
control strategies
Copying descriptions to another controller
Using BACtalk Builder
Using Device Manager
Writing object names and descriptions to Gen4 devices
How objects are defined
Differences between Gen4 ROC versions
ROC versions earlier than 4.10b4
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Writable
DDC
ROC versions 4.10b4 and later
Benefits
Flash memory and text strings in the VLC
Object names
Object descriptions
Freeing up text strings
Upgrading Gen4 ROC files
Reverting to earlier versions of Gen4 ROC files
Updating existing applications
Writing VLC-444 object names and descriptions
Upgrading ROC files
Setting DDC to make points writable
Writing object names and descriptions from displays
Where VLC-444 object name values come from
Where VLC-444 descriptions come from
Chapter 6: DDC function reference
Function 1: End of Normal Sequence
Function 2: End of Subroutine (global controller only)
Function 3: Set Context (global controller only)
Function 6: Velocity Pressure to fpm Converter
Function 8: Enthalpy Calculator
Function 9: Wet Bulb Calculator (Advanced VLC only)
Function 10: Two-Input AND Gate
Function 11: Six-Input AND Gate
Function 12: Two-Input OR Gate
Function 13: Six-Input OR Gate
Function 15: One Shot
Function 16: Delay on Make (seconds)
Function 17: Delay on Break
Function 18: Two-Input Exclusive OR
Function 20: Flip Flop Gate
Function 21: Anti Short Cycle Relay
Function 22: Analog Comparator
Function 23: Change of State (COS) Detector
Function 24: Restrictor
Function 26: Priority Array Read (VLC only)
Function 27: Increment/Decrement
Function 28: Gated Transfer
Function 29: Gated Priority Transfer (VLC only)
Function 30: Subtraction
Function 31: Addition
Function 32: Transfer Data
Function 35: Multiplication
Function 36: Division
Function 39: Within a Range
Function 40: Switch
Function 41: High/Low Limiter
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Function 44: Run-time Accumulator
Function 45: Two-Point Linear Converter
Function 46: Linear Converter
Function 47: Sample and Hold
Function 48: Analog to Timed Binary Converter
Function 49: Thermal Valve, Modulating Output (VLC only)
Function 50: High/Low Selector
Function 51: Proportional Integral (PI) Controller
Function 52: Proportional Integral Derivative
(PID) Controller
Function 54: Floating Motor Controller with No Time-out
Function 55: Floating Motor Controller with Time-out
Function 60: Read External Device (VLC v4.02 or later)
Function 61: Read External Slave Device
(VLC v4.02 or later)
Function 62: Write External Device (VLC v4.02 or later)
Function 63: Write External Slave Device
(VLC v4.02 or later)
Function 67: Subroutine Caller (global controller only)
Function 70: Polynomial (Advanced VLC only)
Function 71: Power (Advanced VLC only)
Function 72: In - Natural logarithm (Advanced VLC only)
Function 73: Log Base 10 (Advanced VLC only)
Function 74: nth Root (Advanced VLC only)
Function 75: Exponential (Advanced VLC only)
Function 76: Sunrise/Sunset Calculator (Advanced VLC only)
Function 77: Daily Schedule (Advanced VLC only)
Function 78: Convert to HHMM (advanced VLC only)
Data Writer
Downloading DDC
Troubleshooting DDC
Chapter 7: Object and property reference
BACtalk expandable controller
Objects in the VLX controller
Properties of VLX AI objects
Properties of VLX AO objects
Properties of VLX AV objects
Properties of VLX BI objects
Properties of VLX BO objects
Properties of VLX BV objects
Properties of the VLX device object
Properties of VLX event-enrollment objects
Properties of VLX file objects
Properties of VLX notification-class objects
Properties of VLX program objects
Properties of VLX schedule objects
BACtalk global controller
Objects in global controllers
Properties of a global controller AV object
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Properties of a global controller BV object
Properties of a global controller calendar object
Properties of a global controller demand limiter object
Properties of a global controller device object
Properties of a global controller event-enrollment object
Properties of a global controller file object
Properties of a global controller notification class object
Properties of a global controller program object
Properties of a global controller schedule object
Properties of a global controller zone object
BACtalk VLC
Objects in BACtalk VLCs
Properties of the VLC AI object
Properties of the VLC AO object
Properties of the VLC AV object
Properties of the VLC BI object
Properties of the VLC BO object
Properties of the VLC BV object
Properties of the VLC file object
Properties of the VLC device object
Properties of the VLC program object
Reserved objects
Microset/Microtouch Reserved AVs and BVs in
BACtalk VLCs
VLD-362 reserved BVs
VAViH-SD Special BVs
Air balance data points
VLC-444 reserved BVs
Advanced VLC objects (VLCA-1688 only)
Reserved AIs
Reserved BVs
AI mode control BVs
Reserved MVs
Properties of the Advanced VLC MV objects
Properties of Advanced VLC Calendar objects
Properties of Advanced VLC Notification Class objects
Properties of Advanced VLC Event Enrollment objects
Properties of Advanced VLC Schedule objects
Properties of Advanced VLC Trendlog objects
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Chapter 8: Scaling factors
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Chapter 9: DDC header file setups in VLC DDC
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Program Information screen
AI setup
AV setup
BO setup
AO setup
Microset Field Service mode custom codes
Setting control flags
Setting parameters for a VAV airflow sensor
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About BACnet, BACtalk, and DDC
1
This chapter describes BACnet, BACtalk and its components, DDC programming,
and how DDC is implemented in BACtalk controllers.
About BACnet
BACnet identifies all information in terms of properties and objects. An object can
represent a physical input or output, or something more abstract, such as a setpoint.
Three elements identify the source of a data point in a BACnet system:
• Device instance: Unique numeric identifier associated with each BACnetcompliant device in a BACnet system. Enables you to reference data in the
device.
• Object ID: Allows the BACnet system to identify and use data. Identifies
specific inputs, outputs, or values—such as outside air temperature or the
status of an on/off switch. Expressed as an object type (such as AI or BO)
and an object instance (a numeral). For example, the object ID AI 1
represents Analog Input 1.
• Property: Describes an aspect of the object with which it is associated.
Each object has some required properties and some optional properties.
The present-value property is the primary reference for most objects.
For example, in a VAV–SD (a VAV box controller), AI-0 is a physical input. Its
most important property is the room temperature, which is conveyed by its presentvalue property. Other properties of the object convey more information: the units
property tells the system that the value is in degrees F, while the description
property indicates that it is a space temperature. (Description properties are
sometimes called descriptors. Unless otherwise used in the user interface, this
guide uses the term description.)
You can examine the device’s protocol information conformance statement (PICS)
to determine which objects a device supports. See the BACnet specification for
more information about BACnet and PICS.
About BACtalk
BACtalk is Alerton’s BACnet-compliant system. Operator workstations, global
controllers (also sometimes called host controllers), expandable controllers, and
VLCs together make up a BACtalk system. All BACtalk components make their
operational data available to other BACnet-compliant devices according to the
BACnet standard.
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The BACtalk operator workstation communicates to other BACnet-compliant
devices over an Ethernet local area network (LAN), WAN using BACnet/IP,
point-to-point (PTP) modem, or serial connection using the BACnet protocol.
Custom displays enable operators to command any BACnet-compliant device.
Programming environments for BACtalk controllers enable developers to
customize the sequence of operations for devices using DDC and VisualLogic.
BACtalk controllers
Each class of controllers has different capabilities with respect to DDC and
building automation features.
Execute .bd3 DDC and host building automation features
such as schedules, trendlogs, and alarms. They orchestrate the operations of
other controllers and have no direct input/output (I/O) capability associated with
them. BACtalk Control Modules—such as BCM-ETH, BCM-HOTEL, BCMFPCS, and BCM-MODBUS—are examples of global controllers.
Global controllers
Execute .bd3 DDC and host building automation
features much like a global controller. The VLX is an example of an expandable
building controller.
Building controllers
Also known as unitary or field controllers.
Used primarily for VAV, VLC, and VLD controllers. Execute .bd4 DDC and
support I/O. VLCs do not support locally stored automation features, relying on
global controllers to supervise these functions.
VisualLogic controllers (VLCs)
Advanced VisualLogic controllers (Advanced VLCs) Also known as VLCAs.
Execute .bd4 and .bd6 DDC and host building automation features such as
schedules, trendlogs, and alarms without a global controller. The VLCA-1688 is
an example of an Advanced VLC.
About DDC programming environments
The programmable logic that controls the sequence of operations in BACtalk
devices is called DDC (direct digital control). DDC sequences are stored and
carried out in BACtalk controllers.
Similarly, automation features—such as optimum start, demand limiting,
trendlogs, schedules, and alarms—that you set up in Envision for BACtalk are
downloaded and stored in global controllers (such as BTI, BTI-100, BCM, VLX,
and VLX-Platinum) and in Advanced VLCs.
DDC sequences are authored and downloaded to BACtalk controllers using
Envision for BACtalk. BACnet objects and properties in these controllers are
visible to other BACnet-compliant devices. Envision for BACtalk has two
environment types (Tools > DDC) for authoring DDC sequences and managing
their execution in BACtalk field controllers: VisualLogic and DDC editors.
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Chapter 1 | About BACnet, BACtalk, and DDC
VisualLogic
VisualLogic is a graphical DDC programming environment that you can use to
manage and author DDC files for all BACtalk controllers that execute DDC. It
requires Microsoft Visio.
Use VisualLogic if you are new to DDC programming, if you need to create
drawings concurrently with your DDC, or if you are familiar with Windowsbased applications.
Files authored for VLCs in VisualLogic are compatible with the VLC DDC
programming environment.
Likewise, DDC files authored for global controllers, expandable controllers, and
BACtalk control modules are compatible with the global or building controller
DDC programming environment. A DDC sequence saved or loaded in one
environment can be opened and viewed in the other.
For more information on using VisualLogic, see “The VisualLogic development
environment” on page 23.
DDC editors
There are three DDC editors, each a different screen color to help distinguish one
from the others:
• Global or Building Controller DDC (Red): Based on Alerton's longstanding DDC programming environment. Used to program all global
controllers (BCMs) and expandable controllers (VLXs). Use global or
building controller DDC if you are familiar with DDC programming in
the IBEX product line or if you are more comfortable with a DOS-style
environment.
• VLC DDC (Blue): An environment similar to global or building
controller DDC, but used exclusively for VLCs, the VLD-362, and the
VAV.
• Advanced VLC DDC (Green): An environment similar to VLC DDC,
but used exclusively for the Advanced VLCs.
I MP O R TA N T When you edit DDC with a DDC editor, only programming
information is saved. Geometric information and comments are lost.
For more information on using the DDC editor, see “DDC header file setups in
VLC DDC” on page 221.
Understanding VLC DDC in the BACnet environment
VLCs provide terminal unit control; they monitor inputs and command outputs
directly through electrical connections to equipment.
Every VLC is fully programmable, although many VLCs are designed for
specific applications and have downloadable, standard operating sequences
created by Alerton (Alerton Standard applications). Values are stored differently
in C3-series and Gen4 VLCs.
© Honeywell
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Programmer’s Guide and Reference | BACtalk Systems
Storage of values in C3-series VLCs
C3-series VLCs have two types of memory: EEPROM and RAM. VLC
EEPROM is capable of storing data indefinitely, even through a power outage.
DDC programming is saved in EEPROM and executes in RAM. All BACnet
setup data is also saved in EEPROM. This way, even if a power outage or other
disaster occurs, the DDC programming is retained in EEPROM and begins
execution on return to a normal state.
The present values of AVs 50-89 are stored directly in EEPROM and are
intended to be used for setpoints or other user input data that will not change
frequently. With the exception of the Run-time Accumulator, these values cannot
be referenced in the output of a DDC function. The Run-time Accumulator
writes to the output only once for every hour of accumulated run-time to help
enforce the 100,000 write cycle limitation.
Note Exceeding the 100,000-write limitation causes indeterminate problems
with a device.
Storage of values in Gen4 VLCs
Gen4 VLCs do not have a limit on the use of AVs 50-89. This is because all AVs
are stored in RAM and backed up in non-volatile flash memory. VLC flash
memory is capable of storing data indefinitely, even through a power outage.
This way, even if a power outage or other disaster occurs, the DDC
programming is retained and begins execution on return to a normal state.
RAM space limitations for certain VLC DDC functions
Some VLC DDC functions store data in VLC RAM between each pass of DDC.
VLCs have a RAM allocation of bytes and bits for this purpose, as shown in
Table 1.
Ta bl e 1
Controller Model Storage Capacities and File Formats
Model
Allowable file
format
Maximum DDC
Byte/bit limits
file size (bytes)
BCM
.bd3
32,768
n/a
VLX
.bd3
32,768
n/a
VLCA -1688
.bd4 and .bd6
65,520
2400/768
Gen 4 VLC
.bd4
14,080
248/191
C3 VLC
.bd4
14,080
72/39
VLC-444
.bd4
14,080
800/256
VLD-362
.bd4
14,080
800/256
Each time you use one of these functions in DDC, the function uses some of this
RAM. If the sum of either bytes or bits used by your DDC exceeds the RAM
capacity, no more functions can execute.
Limit usage of devices in Table 2 through Table 4 accordingly so that your VLC
DDC program does not exceed the byte/bit limit.
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© Honeywell
Chapter 1 | About BACnet, BACtalk, and DDC
Ta bl e 2
C3, Gen4, and VLD-362 VLC DDC functions that use VLC RAM
Function
Bytes Used
Bits Used
15: One Shot
0
1
16: Delay on Break
2
0
17: Delay on Make
2
0
20: Flip Flop
0
1
21: Anti Short Cycle Relay
2
1
22: Analog Input Comparator
0
1
23: Change of State Detector
4
0
24: Restrictor Relay
4
0
44: Run-time Accumulator
2
0
47: Sample & Hold
4
0
48: Analog to Timed Binary Converter
2
0
51: Proportional Integral Controller
4
0
52: Proportional Integral Derivative Controller
16
0
54: Floating Motor Controller with No Time-out
2
0
55: Floating Motor Controller with Time-out
4
0
60: RED
2
0
61: REDS
2
0
62: WED
5
0
63: WEDS
8
0
Bytes Used
Bits Used
15: One Shot
0
1
16: Delay on Break
2
0
17: Delay on Make
2
0
20: Flip Flop
0
1
21: Anti Short Cycle Relay
2
1
22: Analog Input Comparator
0
1
23: Change of State Detector
4
0
24: Restrictor Relay
4
0
44: Run-time Accumulator
2
0
47: Sample & Hold
4
0
48: Analog to Timed Binary Converter
2
0
51: Proportional Integral Controller
4
0
52: Proportional Integral Derivative Controller
16
0
54: Floating Motor Controller with No Time-out
2
0
55: Floating Motor Controller with Time-out
4
0
Ta bl e 3
VLC DDC functions that use VLC-444 RAM
Function
© Honeywell
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Programmer’s Guide and Reference | BACtalk Systems
Ta bl e 3
VLC DDC functions that use VLC-444 RAM (Continued)
Function
Bytes Used
Bits Used
60: RED
2
0
61: REDS
2
0
62: WED
5
0
63: WEDS
8
0
Ta bl e 4
RAM
14
VLC DDC functions that use Advanced VLC (VLCA-1688 only)
Function
Bytes Used
Bits Used
8: Enthalpy
16
0
9: Wet Bulb (Advanced VLC only)
20
0
15: One Shot
0
1
16: Delay on Break
4
0
17: Delay on Make
4
0
20: Flip Flop
0
1
21: Anti Short Cycle Relay
4
1
22: Analog Input Comparator
0
1
23: Change of State Detector
4
0
24: Restrictor Relay
4
0
44: Run-time Accumulator
4
0
47: Sample & Hold
4
0
48: Analog to Timed Binary Converter
2
0
51: Proportional Integral Controller
4
0
52: Proportional Integral Derivative Controller
20
0
54: Floating Motor Controller with No Time-out
4
0
55: Floating Motor Controller with Time-out
8
0
60: RED
4
0
61: REDS
4
0
62: WED
12
0
63: WEDS
12
0
76; Sunrise/Sunset Calculator
24
0
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Identifying and using system data
2
When you program BACtalk DDC, there are six primary objects you work with—
AIs, AOs, AVs, BIs, BOs, and BVs. These are binary and analog inputs, outputs,
and values. Additionally, some devices use multistate objects.You typically
manipulate only the present value of these properties in DDC. This chapter
addresses working with those objects.
Inputs and outputs (AIs, AOs, BIs, BOs)
Inputs (AIs and BIs) are directly associated with physical electrical input
connections to a field-level controller. As such, they never have values written to
them and appear only on the input side of a DDC function.
Conversely, outputs (AOs and BOs) are directly associated with physical electrical
output connections to a field-level controller. Outputs can appear on the input or
output side of a DDC function.
All C3 and Gen4 VLC field controllers have an equal number of logical inputs and
outputs (BOs and AOs), but the configuration of the hardware determines the
actual number of physical inputs and outputs.
However, VLD, VLC-444, and VLCA-1688 field controllers have logical inputs
and outputs (AI, BI, AO, and BO) only for the physical inputs and outputs that are
available.
Therefore, C3 and Gen4 VLCs are interchangeable for DDCs, but VLC-444 and
VLCA-1688 controllers are not.
Note When you write to an AO or BO in VLC, VLD, or Advanced VLC DDC,
you actually write to the priority array at index 14; whereas BCM and VLX DDC
write to index 9. When you read an AO or BO in DDC, you read the present value.
See “Priority arrays” on page 18 for more information.
Values (AVs and BVs)
Values (AVs and BVs) are objects in the field-level controller used for calculated
values, setpoints, timers, and lockouts—virtually any value not directly associated
with a physical input or output. C-3 series VLCs have limitations on how AVs can
be used in DDC. See “Understanding VLC DDC in the BACnet environment” on
page 11 for more information.
© Honeywell
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Programmer’s Guide and Reference | BACtalk Systems
Multistate objects (MIs, MOs, and MVs)
Some non-Alerton devices—such as fans with high, medium, low, and off
settings—use multistate objects. When you program DDC, you work with
multistate objects in the same way you work with analog and binary objects.
However, there are a couple of things to consider when working with multistate
objects:
• All DDC must be programmed using ordinal values. DDC editors
cannot display the text corresponding to the values.
• Multistate inputs, outputs, and values are listed as either I/O point or
BACnet Object options in VisualLogic and global or building controller
DDC and Advanced VLC DDC.
Special point types available in DDC
In addition to the typical I/O points you work with in DDC (the present-value of
AVs, BVs, AIs, AOs, BIs, and BOs), there are additional data points available, as
shown in Table 5.
Ta bl e 5
16
Special data points available in DDC
Point Type
Availability
Remarks
Branch
BCM (0-2047)
VLX (0-2047)
VLC (0-7)
VLD (0-7)
Advanced VLC (0-23)
Provides temporary storage for a data value
or status.
Data
Global controller
Building controller
Advanced VLC
VLC
VLD
Enables you to type a data value, either
Boolean or a real number.
Initialize
Global controller
Building controller
Advanced VLC
VLC
VLD
A flag that is set ON during the first pass of
DDC, after a power cycle, when sending new
DDC, or after a processor reset.
Comm Fail
Advanced VLC
VLC
VLD
Gen4 and later only. A flag that is set ON
only when the VLC loses communications
with a global controller. The VLC Comm Fail
flag is set when communications have been
lost for five minutes and reset whenever a
valid MS/TP message for the given VLC is
received.
Current Time
Global controller
Building controller
Advanced VLC
VLC
VLD
Provides the minutes elapsed since midnight.
Valid range is 0-1440.
MAC Address
Global controller
Building controller
VLC
VLD
Advanced VLC
The decimal value of the MS/TP MAC
address. Valid range is 0-127.
LTBT-TM-PRGRMR
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© Honeywell
Chapter 2 | Identifying and using system data
Ta bl e 5
Special data points available in DDC (Continued)
Point Type
Availability
Remarks
MS/TP Device
Count
Global controller
Provides a count of the devices currently
communicating on the global controller’s
MS/TP LAN.
Free Core
Memory
Global controller
Amount of core memory available, in bytes.
With only real-time operating code (ROC)
loaded, capacity is appx. 233908.
Free Object
Memory
Global controller
Amount of object memory available, in bytes.
With only ROC loaded, capacity is appx.
2031432.
Free Paged
Heap
Global controller
Amount of free paged heap memory
available, in bytes. With only ROC loaded,
capacity is appx. 1048180.
Using NOT and REV on function inputs and outputs
In DDC, you can choose to reverse (REV) or negate (NOT) an input or output.
Reversing and negating are two distinct operations.
REV The REV operation applies only to analog data values (real numbers).
When an analog value is reversed, the result is a value equal to 100 minus the
initial value. For example, if you reverse a function with a value of 20, the actual
value is 80 (100-20=80). Apply the REV operation only when the analog span is
1-100.
NOT The NOT operation applies only to binary inputs and outputs. Applying
the NOT operation to an ON value results in an OFF value. Likewise, applying
the NOT operation to an OFF value results in an ON value.
The NOT and REV operations can be applied to the output of any DDC function.
However, neither operation can be applied to the input of a DDC function that
accepts an analog value. For example, you cannot apply the REV or NOT
operation to the input to Function 40: Switch because the inputs for that function
are analog and are not affected by the operation.
See also “Considerations” on page 69 about using the NOT and REV operations.
© Honeywell
LTBT-TM-PRGRMR Rev. 13
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Programmer’s Guide and Reference | BACtalk Systems
Priority arrays
BACnet uses a priority array to control the present-value property of certain
objects, as shown in Table 6.
Ta bl e 6
BACtalk objects that have priority arrays
BACtalk device
Objects that have priority arrays
VLCs, VLDs, and
VLC-444s, VAVs
BOs, AOs, and BV-40
Global controllers
BVs
Advanced VLCs
AOs, BOs, BVs (250-299), AVs (250-299)
VLXs
AOs, BOs, BVs, AVs
Because a number of commands may be issued simultaneously for a presentvalue property—for instance, an operator may command a fan ON while a
schedule calls for it to be OFF—a scheme for prioritizing commands is
necessary. This is achieved with the priority-array property. Other manufacturers
may use a priority-array for other object types.
Every command for an AO or BO has a priority array index from 1 to 16
associated with it. Priority 1 is the highest, priority 16 is the lowest. Some
priorities are designated by BACnet (priority 1, for example, is reserved for use
by life/safety systems). When a command is issued for a present-value property
of a BACtalk AO or BO, rather than directly affecting the present-value, the
object stores the value in its priority-array property at the appropriate priority
index.
Impo rtant The command with the highest priority drives the present value.
See Figure 1 on page 19 for an example.
For a lower priority command to take effect, a NULL value—not an OFF
value—must be written to all higher levels. For example, if a fire safety system
(priority 1) writes an OFF value to a BO that controls a fan, the fan will remain
OFF, regardless of commands written to that BO at priorities 2 through 16. The
fire system, or some other system, must write a NULL value to the BO at priority
1 before any of the lower priority level commands will be effective.
Note A relinquish-default determines what status or value will take effect when
all levels of the priority-array are NULL.
Note If the out-of-service property is set to TRUE in a VLC or an Advanced
VLC, the present value reflects the resolution of the priority array. The out-ofservice flag controls the relationship of the physical BO to its present value.
When out-of-service = TRUE, the physical BO is decoupled from its present
value. The physical value is the result only of DDC execution in the VLC while
the present value continues to respond to the entire priority array.
Note Setting an AO or BO to out-of-service to TRUE in the VLX leaves the
physical output at the last commanded state.
Note Setting AI/BI to out-of-service true in the VLX allows writing to the
object’s present-value.
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© Honeywell
Chapter 2 | Identifying and using system data
Note When writing to an AO, BO, AV or BV in a VLX (present-value) DDC
writes to index 9. This is also true of BVs in global controllers.
By default, .bd3 DDC
files write to Priority 9.
By default, .bd4 and
.bd6 DDC files write to
Priority 14.
For VLC, VLD, and
Advanced VLC, when an
AO or BO is out of
service, the physical
output responds only to
Priority 14.
Figure 1
Priority array tables
Subroutine DDC
You can use subroutine DDC to make your DDC program more efficient. You
should program a subroutine any time a calculation or control sequence needs to
be implemented repeatedly. For instance, you may need to convert fpm to cfm
for a number of VAV boxes. Or you may need to control equipment in 65 hotel
rooms in exactly the same way, but each must control equipment according to its
own ambient conditions. These are both perfect opportunities for using
subroutine DDC.
CAUTION Only reference devices in subroutine DDC if they are connected to
the MS/TP network on the global controller. Additionally, you should never
reference devices that do not exist (for example, devices that you plan to add in
the future). Failure to follow these guidelines can cause significant degradation
in network performance and temporary communication delays of up to several
minutes.
© Honeywell
LTBT-TM-PRGRMR Rev. 13
19
Programmer’s Guide and Reference | BACtalk Systems
SEQUENCE
NUMBER
DDC Function
SUBROUTINE STARTING
SEQUENCE
0
1
1
2
Notes
2
3
Num bers represent
each tim e a subroutine
is called from within
norm al DDC. The lines
indicate the
progression of the
logic. Bold lines
indicate when the
subroutine is
sum m oned by a subcaller function, while
regular lines indicate
the return to norm al
DDC when function 2
is encountered.
Figure 2
20
4
5
5
yy
1550
67
1560
yy
1570
67
1580
xx
2830
2840
2850
67
67
yy
3100
3110
3120
zz
67
xx
Sub-Caller (Start 6500)
4000
01
END OF NORMAL
6500
yy
7520
02
7530
zz
8110
02
Sub-Caller (Start 7530)
Sub-Caller (Start 6500)
Sub-Caller (Start 7530)
Sub-Caller (Start 7530)
END OF SUBROUTINE
SUBROUTINE DDC
1, 3, and 4 all call the
sam e subroutine, each
passing it different
values. The sam e is
true for 2 and 5. Each
tim e the sam e
subroutine is executed
with different values,
it's called an iteration.
3
4
xx
20
NORMAL DDC
xx, yy, and zz
represent any
m iscellaneous DDC
functions.
10
END OF SUBROUTINE
Graphical depiction of a DDC program execution with subroutine callers
LTBT-TM-PRGRMR
Rev. 13
© Honeywell
Chapter 2 | Identifying and using system data
The VAV Subcaller (sequence #1000) will call on
the Set Context Function #5000 in a VAV
Subroutine.
The first function in the subroutine is Function 3:
Set Context, with Substitution Point 0 entered as
the Context Device Instance. All subsequent data
points in the subroutine DDC that must reference
the associated VAV are entered with the Subroutine
Context Device check box selected.
In this example, the Comparator function will look
at value of AV-1 in the Subcaller device (plus input)
and compare it to value 30 (minus input).
Figure 3
© Honeywell
Subroutine caller
LTBT-TM-PRGRMR Rev. 13
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Programmer’s Guide and Reference | BACtalk Systems
22
LTBT-TM-PRGRMR
Rev. 13
© Honeywell
The VisualLogic development
environment
3
VisualLogic uses the Visio® drawing and design tool as its engine. When you start
VisualLogic, custom menu items and functions in Visio enable you to author and
manage DDC files in Alerton BACtalk controllers.
Installing and using Visio
If you plan to use VisualLogic, install Visio 2007 or Visio 2010. Alerton
recommends that you install Visio in the default installation directory.
I MP O R TA N T VisualLogic 3.0 is supported in Visio 2007 or Visio 2010.
I MP O R TA N T Before starting VisualLogic in Visio 2007, set the macro security
level to Low. Before starting VisualLogic in Visio 2010, add Alerton to the list of
trusted publishers.
CAUTION If you upgrade from Visio version earlier than 2007, completely
uninstall the earlier version before installing the later version. If earlier versions are
not uninstalled, VisualLogic does not work properly.
Note See Envision for BACtalk Installation and Startup Guide (LTBT-TM-
ADMIN30) for system requirements.
Both Visio 2007 and Visio 2010 offer the same VisualLogic functions. The
difference between the versions is in the method in which you access the functions.
• Visio 2007: Uses menu paths and toolbars for access to functions.
• Visio 2010: Uses a ribbon in which functions are grouped on tabs, as
shown in Figure 4. To access a function, select the appropriate tab and then
click the icon for the desired function. Offers the following advantages:
• Easy to use. More visually-oriented than menu paths.
• Ribbons can be customized to user preference, which can save time
during device configuration.
Figure 4
© Honeywell
Microsoft Visio 2010 ribbon
LTBT-TM-PRGRMR Rev. 13
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Programmer’s Guide and Reference | BACtalk Systems
Note See Visio online Help or other Microsoft user documentation for
instructions for installing Visio, for general information about using Visio and its
toolbars, commands, and ribbon; and for configuring the ribbon.
Using VisualLogic
In VisualLogic, the DDC programming is represented by a Visio file. When you
save the drawing, code for the VLC, global controller, building controller, or
Advanced VLC is saved along with it. This means that you can generate a DDC
program from a Visio drawing.
Likewise, you can use VisualLogic to retrieve a DDC program from a device and
convert it into a Visio drawing.
You can use VisualLogic to:
• Author DDC in a graphical environment, creating documentation
simultaneously as you program.
• View data in real-time from BACtalk controllers, monitoring DDC
execution to test and verify operation.
• Manage DDC files on the operator workstation hard disk and in field
controllers, reading and loading DDC even if the sequence was authored
in BACtalk’s other development environments.
• Set up the unit of measure and other object properties in VLCs, global or
building controllers, and Advanced VLCs.
Figure 5 identifies the key elements in VisualLogic (using Visio 2007) that you
use to execute commands, author DDC, and set device and drawing properties.
24
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 3 | The VisualLogic development environment
The VisualLogic menu has custom commands for VisualLogic
Drawing with sample code.
The drawing title block lets
you set the DDC file location
(rep and job), file name, revision
number, and display number.
Double-click the icon to view the
Program Information dialog box.
The VisualLogic stencil contains
function shapes. Click a function on the
stencil, drag it to the drawing page and
then drop it. Double-click the function
after you place it to set I/O and other
parameters. Use the connector tool to link
functions.
Visio toolbars and menu items enable you
to draw, format, and manipulate objects in the
drawing and set drawing properties. On the
View menu, point to Toolbars to select the
toolbars that you want to view.
Figure 5
The device settings icon lets you set up points,
specify scaling, customize Microset programming,
import or export data and configure other settings for
the device. A VLC, global or building controller, or
Advanced VLC appears depending on the type of DDC
program you are viewing. Double-click the icon to view
the Device Settings dialog box.
Key components of the VisualLogic development environment
When you start VisualLogic, the Visio development environment opens with a
blank workspace. You can then either create a new VisualLogic drawing, load
one from file, or load one from a BACtalk controller on the network.
Note When switching between versions of Envision for BACtalk—for
example when you upgrade from one version of Envision for BACtalk to the
next—you have to start VisualLogic twice. The first start resets Visio add-on
directories. The second start uses the add-on directories to start the correct
VisualLogic version.
© Honeywell
LTBT-TM-PRGRMR Rev. 13
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Programmer’s Guide and Reference | BACtalk Systems
 To start VisualLogic
Do one of the following:
• From an open instance of Envision for BACtalk, from the menu bar,
select Tools > DDC > VisualLogic.
Visio starts with a VisualLogic menu in the menu bar (in Visio 2007, as
shown in Figure 5 on page 25) or as a tab in the ribbon (in Visio 2010,
as shown in Figure 4 on page 23).
Note Alerton recommends that you have only one instance of VisualLogic
open at a time. Because VisualLogic requires substantial memory, having
multiple instances open slows performance.
About the VisualLogic Toolkit
The VisualLogic Toolkit combines all the VisualLogic functions in a dockable
dialog box with related functions grouped on tabs, as shown in Figure 8 on page
32. Keep this timesaving toolkit open for quick access to popular design tools
while creating and debugging DDC drawings.
 To open the VisualLogic Toolkit
Do one of the following:
• Visio 2007: From the menu bar, select VisualLogic > Tools >
VisualLogic Toolkit (or press SHIFT+ALT +E).
• Visio 2010: On the VisualLogic tab, click VisualLogic Toolkit (or
press ALT+V+K).
Features
The VisualLogic Toolkit offers the following features that save time when
developing and testing DDC files:
• Dockable: Drag the toolkit by its banner (the top edge) and attach it to
any edge of a DDC drawing.
• Autohide: Collapse the toolkit so that it appears as only a bar at the
edge of the drawing. To turn the autohide feature on or off, click the
pushpin icon on the side of the toolkit.
• Multiple instances: You can have a toolkit open for each open drawing
page. Focus switches as each drawing is selected.
• Stays open: You can keep the VisualLogic Toolkit open, even when
other dialog boxes are open, meaning that you can quickly toggle
between the toolkit and other tools.
• Sortable table columns: Click on a column header to sort data in
ascending or descending order. (Not all tabs present tables.)
• Sizable table columns: Drag columns to desired width. (Not all tabs
present tables.)
Best practices
Alerton recommends the following best practices when using the VisualLogic
toolkit:
26
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 3 | The VisualLogic development environment
• Use a dual monitor so that you can drag the open toolkit to the
secondary monitor, leaving the primary monitor available for
workspace.
• If a dual monitor is not available, use a wide-format screen.
• When the VisualLogic toolkit is docked, use the pushpin feature to turn
autohide on and off as desired.
Using shortcut keys
VisualLogic offers key sequences (commonly called shortcut keys or hot keys) as
a short cut for accessing many menu and ribbon functions, as shown in Table 7.
Note In Visio 2010, if the ribbon is truncated on the screen (for example when
the Visio workspace is reduced to a narrow window), shortcut key combinations
change. However, when you press ALT, a letter appears on the ribbon to identify
current shortcut key combinations. To use shortcut key combinations when the
Visio 2010 ribbon is truncated, press ALT and follow shortcut key combinations
as designated by letters on the ribbon. The shortcut key combinations shown in
Table 7 work for a fully-expanded ribbon.
Ta bl e 7
© Honeywell
VisualLogic shortcut keys
Action
Visio 2007 shortcut key Visio 2010 shortcut key
VisualLogic tab
ALT+L
ALT+V
Comments
ALT+ L +C (then press E to
edit or V to view)
ALT+V+C (then scroll down
to Edit or View and press
ENTER)
New drawing
ALT+L+N
ALT+V+N
Straighten down
ALT+L+S+D
ALT+V+S+D
Straighten up
ALT+L+S+U
ALT+V+S+U
Straighten left
ALT+L+S+L
ALT+V+S+L
Straighten right
ALT+L+S+R
ALT+V+S+R
Read DDC from device
CTRL+ALT+A
ALT+V+R
Read DDC from file
CTRL+ALT+B
ALT+V+F+L
Send DDC to device
CTRL+ALT+C
ALT+V+D+D
Send DDC file to device
CTRL+ALT+D
ALT+V+F+D
Save drawing as DDC
CTRL+ALT+E
ALT+V+D+C
Save as Advanced LVLC
DDC
CTRL+ALT+L
ALT+V+A
Open drawing
CTRL+ALT+O
ALT+V+O
Save as drawing
CTRL+ALT+S
ALT+V+S+A
Insert junction
None
ALT+V+J
Device settings (for .bd4
and .bd6 files only)
None. Instead, double-click
the device settings icon on
the first page of the drawing.
ALT+V+D+S
Resequence functions by
order of selection
SHIFT+ALT+A
None
Resequence functions by
existing sequence order
SHIFT+ALT+B
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Ta bl e 7
VisualLogic shortcut keys (Continued)
Action
Visio 2007 shortcut key Visio 2010 shortcut key
Check DDC Drawing
SHIFT+ALT+C
None
Open VisualLogic Toolkit
SHIFT+ALT+E
ALT+V+K
Live Data - view
SHIFT+ALT+L
ALT+V+L+V
Propagate parameters
SHIFT+ALT+P
ALT+V+P
Get DDC Stats
SHIFT+ALT+S
None
Update descriptions on I/O
tabs
SHIFT+ALT+U
None
Live Data - options
SHIFT+ALT+V
ALT+V+L+O
Wrap descriptor
SHIFT+ALT+W
ALT+V+W
Note Additionally, the Visio shortcut keys shown in Table 8 are useful when
working with DDC drawings:
Ta bl e 8
Visio shortcut keys
Action
Visio 2007 shortcut key Visio 2010 shortcut key
Select all
CTRL+A
CTRL+A
Zoom to show the entire
page
CTRL+W
CTRL+SHIFT+W
Group
CTRL+G
CTRL+SHIFT+G
Ungroup
CTRL+U
CTRL+SHIFT+U
Select pointer tool
CTRL+1
CTRL+1
Select connector line
CTRL+3
CTRL+3
About DDC and drawing files
When you create or work with a drawing file in VisualLogic, you are actually
working with one of two separate file types:
• Visio drawing file (.vsd file extensions): Contains all drawing
information and all DDC program information. Typically much larger
than their corresponding DDC files and open more quickly. Can be
opened only in Visio.
• DDC files (.bd3, .bd4, and .bd6 file extensions): Compiled version of
Visio file, contains all DDC programming information. Depending on
the options that you select in the VisualLogic Toolkit, may also contain
drawing information such as descriptions, comments, and geometric
information.
See more information about selecting a format under “Saving your work” on
page 33.
By default, when you work on files in VisualLogic, files are saved to the
following path: C:\Alerton\BACtalk\<version>\<rep>\<job>\DDC,
where <version> represents the currently-installed version, <rep> represents the
representative, and <job> represents the specific job.
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DDC files are identified by file extensions as shown in Table 9.
Ta bl e 9
DDC file extensions and supported controllers
DDC extension type
Supported in development environments
.bd3
Global controller, BCM, VLX
.bd4
VLC, VLD, Advanced VLC, VAV
.bd6
Advanced VLC
The three file extensions are not interchangeable; generally a file that you create
in one device format cannot be converted to another. The exception to this rule is
that you can save a .bd4 DDC as a .bd6 DDC. (See instructions on page 34.)
You can open these files from within VisualLogic or from within the appropriate
DDC development environment in Envision for BACtalk.
Creating and opening VisualLogic and DDC files
While you can open any Visio file through the Visio File menu, when you work
with Visio files that contain DDC programming information, always use the
VisualLogic menu (on Visio 2007) or the VisualLogic tab (on Visio 2010).
 To create a new DDC program in VisualLogic
1. Do one of the following:
• Vision 2007: From the VisualLogic menu, select New Drawing.
• Visio 2010: On the VisualLogic tab, click Open Drawing.
The Device Type Selection dialog box appears, prompting you for the
type of device you are programming (VLC, global controller, building
controller, or Advanced VLC).
2. Select the type of device you are programming and then click OK.
A new drawing opens for the type of device you selected on a blank
workspace.
 To open an existing DDC (.bd3, .bd4 or .bd6) file in VisualLogic
1. Do one of the following:
• Visio 2007: From the VisualLogic menu, select File > Read DDC
from File.
• Visio 2010: On the VisualLogic tab, click Read from File.
The Open DDC File dialog box opens to the DDC folder for the rep and
job you are logged in to.
2. In the Files of type field, select the format of file that you want to open.
3. If necessary, select a different folder from the DDC Files Available in
<rep>/<job> list.
4. In the list of files, select the file name that you want, and then click
Open.
VisualLogic generates a new drawing based on information in the DDC
file. Conditions under which the file was created and saved dictate the
rendering in VisualLogic.
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 To open a DDC file saved as a Visio drawing (.vsd)
1. Do one of the following:
• Visio 2007: From the VisualLogic menu, select File > Open
Drawing.
• Visio 2010: On the VisualLogic tab, click Open Drawing.
2. In the Open dialog box, navigate to the folder and file you want, and
then click Open.
 To open a DDC file directly from a VLC, global controller, or Advanced
VLC
1. Make sure Envision for BACtalk is running and the controller you want
to work with is online.
2. Do one of the following:
• Visio 2007: From the VisualLogic menu, select File > Read DDC
from Device.
• Visio 2010: On the VisualLogic tab, click Read from Device.
3. In the Read DDC dialog box that appears, type the device instance.
4. Click OK.
VisualLogic constructs a drawing based on the DDC in the controller.
Connectors and other geometry information may not be retrievable.
N o t e It may take up to 15 minutes to construct a complex DDC
program.
Setting program information
Program information (also sometimes called application information) is the
descriptive text about the VisualLogic drawing that appears in the title block
(Figure 6) on the first page of a DDC drawing.
Figure 6
Drawing Title Block (left) and Program Information dialog box
There are two methods for editing program information:
• Opening the title block editor (on the right in Figure 6) by doubleclicking the title block.
• Using the Program Info tab of the VisualLogic toolkit (Figure 7).
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The Program Info tab allows you to make changes to the DDC title block from
any page of the DDC instead of having to navigate to the first page of the
drawing, where the title block is located.
Set this field manually. It does
not automatically increment.
Figure 7
Click to send new
information to the title block.
Click to bring information from
the title block to this tab.
VisualLogic Toolkit (Program Info tab)
Changes that you make on this tab are reflected in the title block. Likewise,
changes that you make directly to the title block are reflected on this tab. (Open
the title block editor by double-clicking the title block on the first page of the
drawing.)
 To set program information
1. Open the Program Information dialog box. Do one of the following:
• Double-click the Program information on the first page of the
drawing.
• In the VisualLogic Toolkit, select the Program Info tab.
2. Set properties according to the guidelines as shown in Table 10.
Tab le 10
DDC program information
Item
Explanation
Alerton
Representative and
Job Name
The DDC file keeps a pointer to the rep\job folder in
the BACtalk root directory, which establishes where
this DDC file is saved. The default is the rep/job you
are logged in to. Maximum of 8 characters.
Program Name
The file name used when you save a DDC file or Visio
drawing file through the VisualLogic menu. Maximum
of 8 characters. Maximum of 8 characters.
Revision
A version number that you can use to track revisions to
the DDC. Maximum of two characters.
Display Number
Identifies the display number that corresponds to this
DDC program. Maximum of 8 characters.
3. Click OK or Save to save your changes.
Changes that you make on the tabs are reflected in the title block.
Note If the VisualLogic Toolkit is open when you make changes to the title
block, click Refresh to update data in the Toolkit window.
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Setting options
The Options tab (Figure 8) allows you to select options for managing files or
controlling which actions occur automatically when you develop and edit DDC.
Saved options are saved to the open DDC drawing and remain selected when the
file is closed and later reopened.
Figure 8
VisualLogic Toolkit (Options tab)
To control file size, the Options tab offers the following features:
• Send DDC options: Allows you to select specific details to send from
the DDC drawing. Typically, controllers have limited memory, and do
not require all the information that is contained in a DDC drawing to
function properly. (See also “Sending DDC to a device” on page 35.)
• Save DDC options: Allows you to select which specific details in the
Visio file (.vsd) are saved to the compiled DDC (.bd3, .bd4, or .bd6).
(See also “Saving your work” on page 33.)
Details such as descriptions, geometric information, and comments are useful to
the programmer, but are not required for the DDC to execute in a device.
To control automated actions, the Options tab offers the following features when
you place a function on a drawing:
• Auto sequencing: Assigns a sequence number to the new function
according to the parameters you select.
N o t e The DELETE key does not work in the Start sequence and
Sequence step fields. To edit these fields, place the cursor at the end of
the text and press BACKSPACE.
• Auto connect: Adds a connector between the new function and the one
nearest to it on the drawing. (The toolkit may not always make the
connection to the input or output to which you intend to connect.)
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• Auto edit: Opens the function parameter dialog box when you place a
function on a DDC drawing.
• Auto propagate: Populates values from the source function to the target
function. Always propagates to a “none” value. When values in both the
source and the target are populated, the default is to propagate from left
to right on the drawing.
Note Always check the results of an automated feature.
For information about changing the defaults that appear on the Options tab, see
“Setting VisualLogic Toolkit defaults” on page 70.
Saving your work
This section addresses options available and considerations when you save a file.
When you edit DDC in VisualLogic, the DDC program you work on is stored in
the memory of the computer running VisualLogic. No changes are made to the
DDC programming in the controller until you send the new DDC program to the
controller.
You can adjust the DDC program at the computer without affecting the
controller’s operation. The controller continues to execute the most recently
downloaded DDC program until a new program replaces the old one. (For
information about downloading new DDC program, see “Sending DDC to a
device” on page 35.)
Selecting a format
When you save a file in VisualLogic, the system allows you to select whether
you save it as a Visio (.vsd) or DDC (.bd3, .bd4, or .bd6) file. (For a list of DDC
file formats for various devices, see Table 9 on page 29.)
Typically, unfinished files are saved as Visio files, while files that are ready to be
sent to a device—or are ready for testing on a device—are saved as DDC files.
Alerton recommends that you always save your work as a Visio file. Visio files
contain all programming information as well as comments, descriptions, and
geometric information. While this information is not required for a DDC file to
execute, that information is useful to programmers when troubleshooting or
otherwise working on files.
Note Saving a file as a DDC file does not automatically save it as a Visio file.
Visio files cannot be opened on devices such as a VLC, a global controller, or an
Advanced VLC. They can be opened only in Visio.
Selecting elements to save
When you save your work as a DDC, you can select whether to include
comments, descriptions, and geometric information. This information is not
necessary for the DDC programming to work and adds to the memory used by
the DDC file.
To select elements to save from the Visio file to the DDC file, use the
VisualLogic Toolkit Options tab (Figure 8 on page 32).
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Saving your work as a Visio drawing
Saving your work as a Visio drawing file (*.vsd) is the best way to ensure that
shapes, connectors, and other drawing elements you added to your DDC file are
saved.
 To save your work as a Visio drawing file (*.vsd)
1. Do one of the following:
• In Visio 2007: From the VisualLogic menu, select Save as
Drawing.
• In Visio 2010: From the VisualLogic tab, click Save as Drawing.
2. Select the folder you want and type a file name in the File Name box.
N o t e If you do not use the same filename and rep/job that are
displayed in the title bar, the file may appear not to save.
3. In the Save as Type field, select Drawing (.vsd).
4. Click Save.
Saving your work as DDC
Saving your work as DDC creates global or building controller DDC (.bd3),
VLC DDC (.bd4), or Advanced VLC (.bd6) files.
 To save your work as a DDC file (.bd3, .bd4, or .bd6)
1. On the VisualLogic Toolkit Options tab (Figure 8), set options as
desired for saving comments, geometric information, and descriptions.
While this information is useful to the programmer, it takes up space on
the controller, which may be limited.
2. Do one of the following:
• In Visio 2007: From the VisualLogic menu, select File > Save
Drawing as DDC.
• In Visio 2010: From the VisualLogic tab, click Save as DDC.
• The Save DDC as File dialog box opens to the DDC folder of the rep
and job you are logged in to or as set in the Drawing Properties
dialog box. The file name is based on the Program Name established
in the Drawing Properties dialog box with the appropriate extension
for the type of device you're programming.
3. If necessary, change the folder or file name.
4. Click Save.
Saving a .bd4 DDC file in a .bd6 DDC format
DDC files that are saved in a .bd4 format can be saved in the .bd6 format.
 To save a .bd4 DDC as a .bd6 DDC
1. Do one of the following:
• In Visio 2007: From the VisualLogic menu, select File > Save as
Advanced DDC (or press CTRL+ALT+ L).
• In Visio 2010: On the VisualLogic tab, click Save as Advanced
DDC.
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2. If VisualLogic presents a list of errors, either address them and resave
the file, or click Close and continue.
Re minder DDC files can be saved with errors and warnings, but
cannot be sent to a device with errors.
3. Wait for a moment while VisualLogic compiles the file.
4. At the Save DDC File dialog box, select the following and click Save.
• From the drop-down list near the top of the dialog box, select a rep
and job in which to save the file.
• In the File name field, enter the desired file name.
Note If you attempt to use the Save as Advanced DDC feature to save a DDC
file that is already saved in that format, VisualLogic presents an error message.
Sending DDC to a device
When you have a DDC drawing open, you can send DDC to any BACtalk
controller on the network. The BACtalk controller saves the DDC in its memory
and executes it locally.
VisualLogic prompts you for information about the device and the DDC file
such as the rep, job, file name, and version. You can save the file to the rep and
job directory in conjunction with the Send command, or you can send files
without saving them (not recommended). VisualLogic requires DDC file
information even if you do not choose to save. This is because the VLC retains
the rep/job information along with the DDC.
When you send a DDC file to a device on the network, consider which elements
of the file to send. If the DDC is too large to fit on the controller, send it without
descriptions, comments, and/or geometric information. These elements are
useful to the programmer, but are not required for the DDC to execute properly
on the device.
Select which elements of a DDC file to send to a device in the VisualLogic
Toolkit Options tab (Figure 8 on page 32).
Note A DDC file that is uploaded from a device on the network contains only
the information that was saved to it.
Sending an open DDC file to a device
When programming information is complete—or you want to test the
programming on a device—you can send a DDC file to its intended device on
the network.
 To send an open DDC file to a device
1. Select which elements to send from the DDC to the device.
On the VisualLogic Toolkit Options tab (Figure 8 on page 32) under
Send DDC options, select which elements to include with the DDC,
and then click Save.
2. Send the DDC to the device. Do one of the following:
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• Visio 2007: From the VisualLogic menu, select Send DDC to
device.
• Visio 2010: From the VisualLogic tab, click Send to Device.
VisualLogic automatically checks the file for errors and warnings.
3. If VisualLogic presents an Errors dialog box, address the errors and
repeat step 2.
Figure 9
Send DDC dialog box
4. In the Send DDC dialog box (Figure 9), complete fields as desired and
as described in Table 11.
This information is duplicated in the Program Information dialog box
(Figure 6 on page 30).
CAUTION Settings that you change in the Send DDC dialog box are
reflected in the drawing properties in the DDC header and the Custom
Properties dialog box.
Tab le 11
36
Send DDC to device settings
Item
Explanation
Device
The device instance of the controller you want to receive the
DDC.
Representative
and Job
Alerton representative and job name. The DDC file keeps a
pointer to the rep\job folders in the BACtalk root directory. If
you choose to save files, this is the rep\job in which they are
saved.
File
The file name of the DDC, which is stored as a pointer within
the program and used if you save the file.
Version
A version number you that can use to track revisions to the
DDC.
Send and save
files
Recommended. Saves a DDC file and Visio drawing file
saved to disk at the same time you send the DDC to a
device.
Saving the file to the local drive preserves all the information
associated with the file, including information that is useful to
the programmer but is not required for the execution of
programming.
Files are saved to <bactalk root>\<rep>\<job> with the name
<file>.bd3|bd4 and <file>.vsd.
Send to device
only
Not recommended. No DDC or Visio drawing files are
created concurrently with the send. Typically used only
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5. Click Send.
Sending a DDC file from disk to device
You can use VisualLogic to send a saved DDC file to a controller without
loading the DDC for editing.
 To send a DDC file from disk to a device
1. Do one of the following:
• Visio 2007: From the VisualLogic menu, select to File > Send DDC
File to Device.
• Visio 2010: On the VisualLogic tab, click Send DDC File to
Device.
The DDC File to Send dialog box opens to the current rep and job
folder.
2. Select the folder and file you want to send, and then click Open.
3. In the Device Instance dialog box, type the device instance of the VLC
or global controller you want to receive the DDC, and then click OK.
To upload a DDC from a device, see the instructions for opening a file from a
device on page 30.
Setting up VLCs and Advanced VLCs with VisualLogic
You can use the Device Settings dialog box to set up DDC header information in
controllers. You can set up input scaling, English or metric units, custom
Microset codes, import/export to an Excel worksheet, and more.
For Advanced VLC DDC, you can also do the following:
• Set execution speed.
• Set up multistate points.
• Populate Microset points.
• Synchronize points.
• Define visibility.
• Fully configure AI type and hardware mode.
• Set BO anticycle times and relinquish default value.
• Set the AO relinquish default value.
Setup data is saved to the controller along with the DDC. If you modify any
setup parameters, make sure you send the DDC to the controller.
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About the Device Settings dialog box
The Device Settings dialog box (Figure 10) contains different tabs depending on
what type of DDC drawing you have open. It is available only for .bd4 and .bd6
file formats.
The Writable/DDC
Descriptions field
appears only on
VLC files.
Figure 10
Device Setting dialog box
 To open the Device Settings dialog box
Double-click the device settings icon (Figure 11), which appears in the
lower right corner of the first page of every DDC drawing.
N o t e In Visio 2010 you can also access the Device Settings dialog box
directly from the VisualLogic Device Settings menu.
Figure 11
drawing)
Device Settings icon (in lower right corner of each DDC
The Device Settings dialog box offers the following features that save time when
developing and testing DDC files:
• Dockable: Drag the dialog box by its banner (the top edge) and attach it
to any edge of a DDC drawing.
• Autohide: Collapse the dialog box so that it appears as only a bar at the
edge of the drawing. To turn the autohide feature on or off, click the
pushpin icon on the right side of the dialog box.
• Stays open: The Device Settings dialog box can remain open and
accessible as you navigate through all pages of the drawing.
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Setting program units
You can set up program units to be English or metric in the Device Settings
dialog box on the General tab (Figure 10 on page 38). This setting determines
how the controller interprets 10K Ohm and 3K Ohm thermistor inputs as well as
Microset- and Microtouch-related points.
For VAV controllers, if program units are set to metric, enter box size in cm; the
device then reports flow in liters per second (lps).
The selection of English versus metric units here can be read in DDC from
BV-71, which is read-only. Most Alerton Standard applications use BV-71 to
modify measurement related calculations according to the program units
selection.
Ta ble 12
BV-71 settings for English/metric
Program Units
BV-71
English
OFF
Metric
ON
 To set program units to English or metric
1. Open the Device Settings dialog box. (See instructions on page 38.)
2. On the General tab, in the Program Units field, select either English
or Metric, and then click OK.
3. Send the DDC file to the controller or save it to file.
Selecting description sets
With the release of the 4.10b4 real-time operating code (ROC) file for Gen4
VLCs, the object name properties of AI, AO, AV, BI, BO, and BV objects are
writable using the standard BACnet services.
However, C3-series VLCs allow only the DDC programmer to enter descriptions
as part of the DDC file and not edit them from a standard operator workstation.
The Writable/DDC Descriptions option allows the DDC programmer to select
whether to use the descriptions embedded in the DDC file or the writable
descriptions.
 To select the description type
1. Open the Device Settings dialog box.
2. On the General tab (Figure 10 on page 38), in the Writable/DDC
Descriptions field, select one of the following:
• DDC: Recommended for devices using ROC 4.10b4 or later.
• Writable: Recommended for devices using a ROC earlier than
version 4.10b4.
N o t e The ability to edit descriptions depends on the version of ROC
file in use. For details, see “Writing object names and descriptions to
Gen4 devices” on page 100.
3. Click OK.
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4. Send the DDC file to the controller or save it to file.
Disabling Microset auto-detection
By default, VLCs detect Microsets connected to Input 0. When connecting a
non-Microtouch thermistor to input 0, you must disable Microset auto-detect.
Avoid connecting dry contact inputs to Input 0.
 To disable Microset auto-detection
1. Open the Device Settings dialog box.
2. On the General tab, in the Microset Auto-detection field, select
Disabled, and then click OK.
3. Send the DDC file to the controller or save it to file.
Protecting the DDC file
To protect against unauthorized reading of the DDC file in the VLC, you can
inhibit reads of the file.
 To set up DDC file protection
1. Back up your DDC.
Impo rtant Once the DDC Read Inhibit option has been set, it cannot
be undone. The only workaround to this protection is to download a
new DDC file.
2. Open the Device Settings dialog box.
3. On the General tab, in the DDC Read Inhibit, select Reads Inhibited,
and then click OK.
4. Send the DDC file to the controller or save it to file.
Setting the DDC execution speed (Advanced VLC only)
When the DDC execution speed is set at 10Hz, the DDC executes ten times per
second (0.1sec). When set at 20Hz, the DDC executes twenty times per second
(0.05sec).
Set the execution speed according to the capabilities of the devices on the
network. Using the faster execution speed requires more memory in the
controller.
 To set up DDC execution speed
1. Open the Device Settings dialog box.
2. Click the General tab, in the DDC Execution Speed, select one of the
following:
• 10 Hz: Default. Select this speed unless the job specification calls for
20 Hz.
• 20 Hz: Common examples of use include fume hood and lighting
control.
3. Click OK.
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4. Send the DDC file to the controller or save it to file.
Importing or exporting DDC data to an Excel worksheet
The Import/Export from/to Excel option on the Device Settings dialog box
General tab (Figure 12) enables you to set up Gen4 VLCs and the Advanced
VLC values for your DDC tables using the provided Excel template from
VisualLogic.
Note By default, the template is saved in the following path:
C:\Alerton\BACtalk\<version>\Rep\<job>\DDC, where <version> represents
the version of BACtalk that you are currently using and <job> represents your
current project directory.
Figure 12
Importing to and exporting from Microsoft Excel files
This feature is useful for quickly importing or exporting large amounts of data to
and from a drawing.
You already know what points are required and how they are distributed across
each controller, so now you can use the power of Excel to get point data
descriptions, object names, and settings into the DDC header. The worksheet
tabs summarize all of the controller inputs and outputs and the drop-down menus
contain only viable choices.
Importing
VisualLogic’s import feature allows you to automatically populate data such as
point descriptions, analog inputs, scaling, and filtering.
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This method is useful when you have multiple points to set up in a drawing, such
as when you have defined device settings objects descriptions in BACtalk
Builder and saved the information in an Excel file. For information on using
BACtalk Builder, see BACtalk Builder User’s Manual (LTBT-BBOPMAN),
found on the Alerton Support Network.
 To import data from an Excel spreadsheet
1. Open the desired drawing in VisualLogic.
2. On the Device Settings General tab, click Import.
The Import Device Settings dialog box appears (middle image of Figure
12).
3. Select the desired Excel file and click Import.
4. At the prompt that indicates device settings import succeeded, click
OK.
VisualLogic populates the Point Setup, Analog Input, Analog Output,
Binary Output, Microset Field Service Setup (for Advanced VLCs only)
tabs with the data that you imported from the Excel file (step 3).
5. Click Apply.
Exporting
Exporting data from a DDC is useful when replicating information from one job
or controller to another.
 To export data to an Excel spreadsheet
1. On Device Settings dialog box General tab (Figure 12), click Export.
The Export Device Settings dialog box opens (similar to the middle
image in Figure 12).
2. Verify the file name and then click Export again to open the standard
.xls file.
3. When the system presents the following message, click OK:
Device settings import succeeded.
VisualLogic opens an Excel file that contains points from the drawing.
By default, the Excel file is saved in the same folder as the DDC for the
rep/job that you are currently logged on to.
Setting point descriptions
You can assign descriptions to the AV, BV, AI, BI, AO, BO and MV points. You
and others can use the descriptions to identify and interpret how the program
uses certain points.
Note In Advanced VLC DDCs (.bd6 files) and with Gen4 VLC (.bd4 files)
with version ROC 4.10b4 and later, you can also edit object names.
The Device Settings Point Setup tab (Figure 13 for .bd6 files, and Figure 14 on
page 44 for .bd4 files) allows you to manually make changes to individual
points. This tab is most often used for minor changes rather than major changes
to a drawing.
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For Gen4
VLCs, these
options
appear under
the Collect
Points button.
These buttons are available only for
Advanced VLC files.
Double-click an
item to open the
editing dialog box.
Selecting this check
box prevents the point
description and point
names from being
changed at an
operator workstation.
Figure 13
Device Settings (Point Setup tab for an Advanced VLC file)
Figure 13 shows the Point Setup tab as it appears for an Advanced VLC file. It
includes a button for populating Microset points.
Figure 14 shows the Point Setup file for a .bd4 file.
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Double-click an item to
open the editing dialog
box.
Figure 14
Device Settings dialog box (Point Setup tab for .bd4 files)
For VLC DDC files, if the Writable/DDC Descriptions option (found on the
Device Settings dialog box General tab) is set to DDC, you can edit descriptions
directly on the drawing.
When you have multiple points to set up in a drawing— such as when you have
defined device settings objects descriptions in BACtalk Builder and saved the
information in an Excel file—you can use VisualLogic’s import feature to
automatically populate point descriptions (described under “Importing or
exporting DDC data to an Excel worksheet” on page 41).
Note For information on using BACtalk Builder, see BACtalk Builder User’s
Manual (LTBT-BBOPMAN), found on the Alerton Support Network.
Under the Collect Points (for Gen4 VLCs) and the Synchronize Points (for
Advanced VLC files) buttons, the Point Setup tab lets you perform the following
actions:
• Collect new points from DDC and add to Point Setup list: Copies
new points and their associated values and descriptions from the
drawing to the Point Setup tab. Does not show updates to previouslylisted points.
• Copy I/O tab descriptions to Point Setup descriptions: Copies new
and updated points from the drawing to the Point Setup tab. Previouslylisted points are updated to show their new descriptions.
• Copy Point Setup descriptions to I/O tab descriptions: Pushes
changes made on the Point Setup tab to the drawing. (See instructions
for editing point descriptions from the Point Setup tab on page 45.)
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 To manually assign new point descriptions or edit existing point
descriptions
1. In the Device Settings dialog box on the Point Setup tab, click one of
the following and select Collect new points from DDC and add to
Point Setup list.
• Collect Points: For .bd4 files.
• Synchronize Points: For .bd6 files.
The purpose of this step is to gather point descriptions from the drawing
to the Point Setup tab, where they are presented in a list format.
2. In the list of descriptions, do one of the following:
• To create a new point description: Double-click the bracketed line
to assign a new description to an object, or click an existing item to
change it.
• To edit an existing point description: Double-click the item that
you want to edit.
3. In the Point Setup dialog box (lower images in Figure 13 and in Figure
14), make the following settings as desired.
• Locked check box (for Advanced VLC file only, optional):
•
Selected: Prevents the descriptions and point names from being
changed at an operator workstation.
•
Deselected: The description and point name is not downloaded
into the controller when sending DDC.
• Point: Enter the Object ID (object type and object instance).
• Point description: Enter a brief description of the purpose of the
point. Note the following character limits:
•
For VLC: 30.
•
For Advanced VLC: 60.
• Make name the same as description (for Advanced VLC files
only, optional):
•
Selecting this check box disables the Point name field and forces
the point name to be the same as the point description.
•
Deselecting this check box enables the Point name field, allowing
the point description and the point name to be different from one
another.
If you select this check box, enter text in the Point description field
as desired.
4. Click OK.
The Point Setup editing box closes.
5. On the Point Setup tab, click Apply.
6. Push the changes from the Point Setup tab to the drawing: Click
Synchronize Points (for a .bd6 file) or Collect Points (for a .bd4 file)
and select Copy Point Setup descriptions to I/O tab descriptions.
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 To delete a point description
On the Point Setup tab, select the description that you want to delete in the
list and then press Delete.
Setting up analog inputs (AIs)
AI setup for VLCs is critical. When you set up an AI, you have several options
for selecting the type of AI and its scaling. These options are applied to the AI
before DDC processing in the VLC.
The Analog Input Setup tab (Figure 15) on the Device Settings dialog box allows
you to manually set individual analog inputs. This method is recommended
when you have only a few inputs to set.
Alternatively, you can import AIs from an Excel spreadsheet (described on
page 41).
These fields
appear only on
Advanced VLC
files.
Figure 15
Device Settings dialog box (Analog Input Setup tab for Advanced DDC)
 To set up AIs manually
1. On the Device Settings dialog box, select the Analog Input Setup tab
(Figure 15).
2. For each AI that you want to work with, under Type, select the input
type according to the following guidelines.
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Tab le 13
Setting up AIs
Type
Explanation
Counts
Input is read in raw counts from 0-4095.
Scaled
When you select a Scaled input type, the Zero (time
base) and Range (pulse value) fields appear. AI =
Zero + (Input * Range/ 4096) where “Input” is the
prescaled input count. See the “Scaled (two point)”
below for a simpler method.
10K Thermistor
Use this input type for Microset or Microtouch
temperature inputs and for 10 k Ohm thermistor
inputs. The AI then reports temperature (in °F or °C
according to the Program Units setting).
3K Thermistor
Use this input type for 3K Ohm thermistor inputs.
The AI then reports temperature (in °F or °C
according to the Program Units setting).
Scaled (two point)
In the Two Point Scale Setup dialog box, select the
VLC model and input type. VisualLogic automatically
calculates and enters Zero (time base) and Range
(pulse value) values. a
PT-1000
(Advanced VCLA only)
1000 Ohm Platinum RTD
Pulse Width
Pulse Totalizer
Pulse inputs not available on VAV controllers.
Pulse Frequency
Resistance
(Advanced VCLA only)
Units set to Ohms. Also sets Hardware field to
Current
(Advanced VCLA only)
Units set to milliamperes. Also sets Hardware field to
Voltage
(Advanced VCLA only)
Units set to volts. Also sets Hardware field to
resistance.b
Current.b
Voltage.b
a. On an Advanced VLC, scales the input to the desired reading, but
does not automatically set the Hardware mode for the appropriate input
connection. If you choose this type, you must also set the appropriate
Hardware mode.
For example, to connect to a 4-20mA device that you want to read 0100% without having to use an external resistor for mA inputs, in the
Type field, select Scaled (Two Point). In the Two Point Scaled Setup
dialog box that appears, in the VLC Model field, select Other Gen 5,
and in the Input Type field, select 4 to 20 mA. Under Scaling Data,
set the input hi/low (4-20) and the output hi/low (0-100), and click OK.
In the Hardware mode field, select Current.
b. Automatically sets the hardware mode, but does not automatically
scale the input at the header. Inputs set to this type must be scaled elsewhere in the DDC for the desired outputs.
3. Under Units, select the type of engineering units you want to assign to
this input.
This option is not available when 10K Thermistor or 3K Thermistor is
selected as Type.
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4. Type zero and range values according to the guidelines for Scaled in
step 3 and the information in the VLC Installation and Operations
Guide (LTBT-TM-GEN4VLC).
N o t e You need to select only the VLC and input type for the Scaled
(two point) option and the time base and pulse values are populated
automatically.
5. If you want to apply filtering to the input, select Filter. The filter
calculation is performed every 0.1 seconds and is expressed as:
NewCount 31
FilteredCount = --------------------------- + ------  PreviousCount
32
32
CAUTION Do not filter any Microset/Microtouch inputs (IN-0).
6. For Advanced VLC files only: In the Hardware mode field, set the BV
as appropriate for your job according to Table 14.
Tab le 14
Setting the hardware field
Hardware
mode
BV-200-215
internal resistor
BV-400-415 pull
up resistor
Default
Off
On
Voltage
Off
Off
Resistance
Off
On
Current
On
Off
Notes
Functionality is
same as resistance
mode
No external resistor
required.
N o t e The DDC sets the BVs above when the DDC is initialized.
These settings can be overwritten by the BACnet write command.
However, at each power cycle the DDC resets these values.
7. For Advanced VLC files only: Select Present. If this check box remains
unchecked, the AI is not used.
8. Click Apply.
Setting up analog outputs (AOs)
In VisualLogic in the Device Settings dialog box, Analog Output Setup tab
(Figure 16), you can assign the unit of measure, the relinquish-default, and the
out-of-service properties for each AO in a VLC.
Alternatively, you can import AOs from an Excel spreadsheet (described on
page 41).
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This check box appears
for Advanced VLC files
only. If you intend to use
this value, select this
check box.
Controls the relationship of
the physical AO to its
present value.
Figure 16
Device Settings (Analog Output Setup tab)
The relinquish-default and out-of-service properties are critical for priority-array
operation.To set up AOs
1. On the Device Settings dialog box, select the Analog Output Setup tab
(Figure 16).
2. Select options according to the following guidelines.
Tab le 15
Setting up AOs
Item
Explanation
Units
Select a BACnet engineering unit ID in this box. The
unit of measure indicates the unit of measure for the
AO. This doesn't affect calculations; it is for display
and reference purposes only.
Relinquish Default
Type a default value for the AO. The valid range is 0
to 100. The relinquish default determines the value
of the AO when all elements in the AO's priority
array are NULL–essentially the default value of the
AO.
Out of Service
Select this check box to set the AO's out-of-service
property to TRUE. The out-of-service property
controls the relationship of the physical AO to its
present value. When out-of-service = TRUE, the AO
is decoupled from its present value, and the
physical AO value is the result only of DDC
execution in the VLC, while the present value still
reflects the priority array.
Present
For Advanced VLCs only. Indicates that the value is
used. If you intend to use this value, select this
check box. Otherwise, the value does not appear on
the function.
3. Click Apply.
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Setting up binary outputs (BOs)
In VisualLogic in the Device Settings dialog box, Binary Output Setup tab
(Figure 17), you assign a relinquish-default and set the out-of-service flag for
binary outputs (BOs) in a VLC.
Alternatively, you can import BOs from an Excel spreadsheet (described on
page 41).
These fields appear
for Advanced VLC
files only.
If you intend to use
this value, select the
Present check box.
Figure 17
Device Settings dialog box (Binary Output Setup tab)
These settings affect the BO present-value and physical output. The relinquishdefault is the status of the BO when all priority-array indexes are NULL. The
out-of-service flag controls the relationship of the physical BO to its present
value. When out-of-service = TRUE, the physical BO is decoupled from its
present value. The physical value is the result only of DDC execution in the VLC
while the present value continues to respond to the entire priority array.
 To set up BOs
1. On the Device Settings dialog box, select the Binary Output Setup tab
(Figure 17).
2. For each BO, make selections according to the following guidelines:
Tab le 16
Setting up BOs
Item
Explanation
Relinquish Default
BO defaults to Active (ON) if all priority-array
indexes are NULL
Out of Service
Decouples the physical BO from its present value
and consigns control exclusively to the VLC's DDC.
Minimum on and off
time (for Advanced
VLC files only)
Sets the minimum time in seconds that the BO is on
or off.
Present (for
Advanced VLC files
only)
Indicates that the value is used. If you intend to use
this value, select this check box. Otherwise, the
value does not appear on the function.
3. Click Apply.
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Setting up analog values (AVs)
For AVs, the extent of setup is assigning a BACnet engineering unit code to the
AV, which is optional.
You can set up AVs on the Device Settings Analog Value Setup tab (Figure 18),
or you can import AVs from an Excel spreadsheet (described on page 41).
This check box
appears only for
Advanced VLC files.
Figure 18
Device Settings dialog box (Analog Value Setup tab)
 To set up AVs
1. On the Device Settings dialog box, select the Analog Value Setup tab
(Figure 18).
2. For each AV, select a BACnet engineering unit.
3. For Advanced VLCs only: Select Present. If this check box remains
unchecked, the value does not appear on the function.
4. Click Apply.
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Setting up multistate values (MVs) (Advanced VLCs only)
On Advanced VLCs only, the Device Settings dialog box Multi State Setup tab
(Figure 19) allows you to set the object instance (0-9) and the desired edit and
view states for MVs.
Figure 19
Device Settings dialog box (Multi State Setup, Advanced VLCs only)
 To set up MVs
1. On the Device Settings dialog box, select the Multi State Setup tab
(Figure 19).
2. For each MV, select an object instance (0-9), edit state, and view state.
3. Click Save, and then click Apply.
Setting up Microset field service codes
The Microset's field service mode enables technicians to query and change the
value of objects in a VLC. You can customize the values that a technician can
change from a Microset and choose the two-digit code that identifies data.
You can also select whether a technician can change—or only view—the value
at the Microset, whether the value appears with a decimal, and whether negative
values are acceptable.
As a technician scrolls through the list of Microset field service codes, the codes
at the top of the list appear first. You can arrange codes in VisualLogic so that the
more frequently queried values appear first. For a list of the standard Microsoft
codes, see “Microset Field Service mode custom codes” on page 225.
Note When a Microset II is in balance mode, only the first five items in this list
are available. Therefore, when you program DDC for a VAV controller, put the
items most useful to your air balancer first.
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You can set up Microset field codes manually by using the Device Settings
Microset Field Service Setup tab (Figure 20) or by importing the data from an
Excel spreadsheet. (See “Importing or exporting DDC data to an Excel
worksheet” on page 41.)
 To set up Microset field service codes using the Device Settings dialog
box
1. On the Device Settings dialog box, select the Microset Field Service
Setup tab (Figure 20).
The tab is populated with a list of the Microset codes set up for the
current DDC program.
Select these
options for all
binary values.
Figure 20
Device Settings dialog box (Microset Field Service codes
2. Do one of the following:
• To add a new field service code: Click Insert New, and doubleclick the blank code entry in the list.
• To edit an existing code: Double-click the code entry on the list.
The Edit Microset Entry dialog box appears.
3. In the Display Digits fields, type or select the first and second digits
that you want displayed at the Microset.
Tab le 1 7
Acceptable Microset Field Service mode characters
0
3
6
9a
c
E
h
J
o
u
-
1
4
7
A
C
F
H
L
p
U
_
2
5
8
b
d
ga
i
n
r
y
a. The characters 9 and g are virtually indistinguishable on the
Microset display.
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4. In the Object fields, type the object type and instance for the present
value that you want to associate with the Display Digits.
5. Select check boxes according to the following guidelines
Check Box
Explanation
Writable
Enable a technician to change the value of object
using the keys on the Microset.
Decimal
Displays decimals (one significant digit) at the
Microset.
NOTE: Select this option for all binary objects.
Unsigned
Ensures that the value is a positive number and is
never negative.
NOTE: Select this option for all binary objects.
6. Click Apply.
Authoring DDC in VisualLogic
To author DDC in VisualLogic, you drag functions from the stencil and drop
them onto your drawing. Once a function is placed, you double-click it to assign
inputs, outputs, sequence numbers, and other parameters.
VisualLogic does not require that the DDC functions appear in any order (they
always execute in order of sequence number) or that they be linked with
connectors. However, arranging functions in logical order makes the DDC much
easier to read, and using connectors enables you to use the Check Drawing and
Propagate Parameter features.
Working with VisualLogic design tools
Once you’ve opened a new VisualLogic drawing you have two options for
accessing the design tools:
• VisualLogic Tools menu (for Visio 2007) or tab on the ribbon (for Visio
2010).
• VisualLogic Toolkit. For details, see “About the VisualLogic Toolkit”
on page 26.
Adding functions to your drawing from the stencil
When you open VisualLogic from Envision for BACtalk, the appropriate stencil
appears based on the file format (.bd3, .bd4, or .bd6).
Note To open the VisualLogic stencil manually, do one of the following:
• Visio 2007: From VisualLogic View menu, select Shapes Window, and
then select the stencil, vislogic.vss, in the <bactalk root>\vislogic folder.
• Visio 2010: On the left side of the screen, click More Shapes and then
select a VisualLogic template. (Expand and collapse the stencil area as
desired.)
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 To add a function from the stencil to your DDC drawing
In the stencil, click the function you want to use and drag it to where you
want it to appear in your drawing.
Setting inputs, outputs, and other function parameters
After you place a function on your drawing, double-click the function to view
the setup dialog box and assign inputs, outputs, and other parameters.
(Alternatively, if the Auto Edit option on the VisualLogic Toolkit General tab
(Figure 8 on page 32) is selected, the Edit dialog box opens automatically when
you place a function on a drawing.)
The fields available on the Edit dialog box are unique for each type of function.
For more information about the function and its parameters, click the Help
button in the dialog box.
Select this check box to use
the NOT or REV operation to
negate the parameter.
Type the sequence number of
the function here. Each
function's sequence number
must be unique.
Figure 21
Click here for
function-specific
online help.
Click here to assign an object and
property or data value to the parameter
listed or type the data directly in the box.
The number of inputs, outputs, and
parameters vary by function.
Function setup dialog box, example (Two-input OR)
Linking functions with connectors
Connectors make your diagram easier to read. They also enable you to use the
Propagate Parameters command.
Functions do not require connectors to link; the sequence numbers and input/
output assignments in the functions’ setup dialog boxes are sufficient for
VisualLogic to determine the order of execution and processing of values.
When you link functions with a connector, the output of one function is not
necessarily linked to the input of another. You still assign inputs and outputs in
the functions’ setup dialog box. The exception is when you use the Propagate
Parameters command or when the Auto Propagate option on the VisualLogic
Toolkit General tab is enabled.
 To use the Auto Connect feature
On the VisualLogic Toolkit Options tab, under Perform actions when
DDC is placed on the drawing, select Auto Connect.
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 To link functions with connectors
1. Click the Connector button
on the Visio toolbar.
2. Position the mouse pointer over a connection point on the source
function.
The pointer appears as a rectangle.
3. Click the connection point, and drag the pointer to the connection
point on the target function.
A red rectangle appears over the connection points as the mouse pointer
is moved close to them.
N o t e To drag a window and zoom in on an area of the drawing, use
CTRL+SHIFT. To zoom out, right-click while holding CTRL+SHIFT.
Alerton offers the following tips for working with connectors:
• Use the Insert Junction connector icon on the VisualLogic tab to place a
junction in the middle of a line: Select a line, and then click the icon.
• Use the Junction shape to create branching connections. Place the
Junction shape, and then use the connector tool to connect to one of the
four connection points on the shape. Zoom in so you do not accidentally
use the wrong connection point on the Junction shape.
• Use the Straighten Connector tools to straighten connectors left, right,
up, or down. Select the connectors you want to straighten, and then click
one of the Straighten tools in the toolbar or point to Connector on the
VisualLogic menu and then choose a Straighten command. Straighten
connectors as a last step.
Propagating function parameters
You can use VisualLogic’s Propagate Parameters feature to assign the output of
one function as input to another function. Use this command after you use Visio
connectors to link the I/Os graphically.
For example, if you assign BV-3 as the output of a function at Sequence 100 and
then use a Visio connector to link it to an input of a function at Sequence 110, the
Propagate Parameters command automatically assigns BV-3 as the input at
Sequence 110.
If you have assigned an input that doesn't match its corresponding output, the
command overwrites the input with the output assignment.
CAUTION If you have multiple I/O assignments using the Junction shape, the
Propagate Parameters feature automatically propagates the assignment of the
output with the lowest sequence number to all the outputs, overwriting previous
assignments.
Automatically
You can set VisualLogic to propagate function parameters automatically when
you place functions on a drawing.
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 To automatically propagate output assignments to input assignments
On the VisualLogic toolkit, Options tab (Figure 8 on page 32), select the
Auto propagate option.
Manually
If the automatic propagation option is not selected, you can propagate
parameters manually, either for all or selected functions.
 To manually propagate output assignments to input assignments
1. Select the functions for which to propagate parameters. VisualLogic
propagates parameters according to the following:
• No functions selected: Propagates parameters for the entire drawing
on all pages.
• Some functions selected: Propagates parameters only for the
selected functions.
• CTRL+A used to select all functions: Propagates parameters for all
functions on the active page. Parameters on inactive pages are not
propagated.
2. Do one of the following:
• Visio 2007: From the VisualLogic menu, select Tools > Propagate
Parameters.
• Visio 2010: On the VisualLogic tab, click Propagate.
Repeating functions
The VisualLogic Repeat tab (Figure 22) provides a quick method of building
multiple similar functions by copying an existing function. This tab is typically
used for building subroutines.
Figure 22
VisualLogic Toolkit (Repeat tab)
The Repeat feature provides a way to create several DDC functions of any kind
at one time. For example, this feature allows you to create multiple subcallers in
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global or building controller DDC. You can increment DDC function parameters
with input specific to each DDC function.
You can also increment the following optional parameters:
• Branch numbers.
• Device instances.
• Object instances.
• Array indexes.
• Substitution numbers.
• Real data values.
Only some of these parameters are applied to particular DDC functions. If the
increment value is zero, the correspondent parameter does not increment.
To use this feature, only one function can be selected.
 To repeat (copy) an existing function
1. On an open DDC, select the function that you want to repeat.
2. On the VisualLogic Toolkit Repeat tab, select the desired repeat
parameters, including the following:
• Number of times that you want to repeat the function.
• Position of the repeated functions: vertically, horizontally, or
diagonally.
N o t e Red shading in the Repeat field indicates an invalid selection.
Either nothing is selected or more than one item is selected. You can
apply the Repeat feature to only one function at a time.
The parameters available depend on the selected function.
3. Click Repeat.
Resequencing functions
Often, a programmer needs to change the sequence of a range of functions while
programming, usually because functions were added or omitted. VisualLogic
allows you to select a range of functions and renumber them as a whole.
Rather than changing sequence numbers one-by-one, you can assign a starting
sequence number and specify the increment of sequential function numbers,
such as 10, 20, 30, or 5, 10, 15.
The Resequence tab on the VisualLogic Toolkit (Figure 23) allows you to
resequence selected or all functions on a DDC.
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Figure 23
VisualLogic Toolkit (Resequence tab)
The Resequence tab offers the following features:
• Select the sequence starting number.
• Select the increment by which functions are sequenced.
• Select whether to use the existing sequence order or to sequence
functions in the order in which you select them.
 To resequence functions on a DDC drawing
1. To resequence functions in their existing order: In an open DDC, select
the functions that you want to resequence.
• To select multiple sequences, use SHIFT+click.
• To resequence all functions on the active page, press CTRL+A.
2. To sequence functions in the order in which you select them: In an open
DDC, use SHIFT+click to select functions in the order in which you
want to select them.
3. On the VisualLogic Toolkit Resequence tab, complete fields as follows:
• Start sequence at: Enter the starting number for the sequence.
• Sequence step: Enter the interval between sequences.
• Resequence order: Select one of the following:
•
By order of selection: Resequences functions in the order you
selected them.
•
By existing sequence order: Resequences functions by their
existing order.
N o t e The DELETE key does not work in the Start sequence at and
Sequence step fields. To edit these fields, place the cursor at the end of
the text and press BACKSPACE.
4. Click Resequence.
VisualLogic renumbers the function with the lowest sequence number
with the Start sequence number. Other functions are numbered in
increasing increments of the Sequence step value.
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Note VisualLogic Toolkit does not present a warning if you inadvertently
assign the same sequence to one or more functions. Instead, a warning appears
when you check the drawing on the Errors tab.
Cross-referencing functions
The Cross-Reference tab (Figure 24) presents a list of all functions in the current
DDC, along with relevant information about each function.
Set parameters and filters here.
Figure 24
The Object Name column appears
only for Advanced VLC (.bd6) files.
Click here to refresh the table after you
make changes to the DDC.
VisualLogic Toolkit (Cross-reference tab)
Note Unless specifically designated as on output in the Input/Output column,
items in the table are inputs.
The Cross-reference tab offers the following features:
• Filterable: By default, the Cross-reference tab shows function detail
from all pages associated with the open DDC. To filter details, select
one or both of the following near the top of the tab:
• Detail from the current page only: Click Show cross reference
table only for the current page.
• Detail from a specific function type: Select the desired function
from the drop-down list. Depending on the data selected, other filters
are enabled.
• Goto: To go to a specific function in the table, double-click it in the
table. (Alternately, select the item and click Go to.) The toolkit opens
the page on which the function appears, with the function selected.
• Edit: To edit a function, select it in the table and click Edit. The toolkit
opens the page on which the function appears and opens the Properties
dialog box of the selected function.
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• Printable: To print the table contents, click Print. VisualLogic
automatically prints the current contents of the table on the default
printer for the computer you are using.
• Supports object description (Advanced VLC (.bd6) files only):
Displays the point description and object ID in either of the following
formats:
• <BACnet point description property> (<object ID>)
For example, Conf Rm temp (AI-0)
• <BACnet point object name property> (<object ID>)
For example, Space temp (AI-0)
• Easy to update: After you make changes to a DDC drawing, click
Refresh to update the cross-reference table.
 To view the cross-reference table
In an open drawing, open the VisualLogic Toolkit and select the Crossreference tab.
 To update the table after changing the current DDC
Click Refresh.
Comparing drawings
The Compare tab (Figure 25) allows you to compare two similar DDC files. This
feature is helpful for identifying changes of the current DDC from the as-built
DDC, thereby allowing you to identify changes that may have been
incorporated.
Figure 25
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The Compare tab offers the following features:
• Printable list of differences.
• Sequence-by-sequence identification of missing or differing sequences
and values.
 To compare two DDC drawings
1. Open one of the two files that you want to compare.
2. In the VisualLogic Toolkit, select the Compare tab.
3. Click Browse, navigate to the second file that you want to compare, and
click Open.
4. On the Compare tab, click Compare.
VisualLogic Toolkit populates the table as shown in Figure 25. The
center column identifies sequences that appear in one DDC but not the
other (by a blank cell) and sequences that contain different values (with
the word Different).
5. To view details about the differences between DDCs, select the desired
line in the table and click Compare Functions. (Alternatively, doubleclick the desired line.)
VisualLogic Toolkit presents a pop-up dialog box that compares
specific details and values, as shown in Figure 26.
Figure 26
Comparing functions in VisualLogic Toolkit
6. Optional: To generate a list of differences, click Generate Report.
VisualLogic Toolkit presents a printable list in Microsoft Notepad.
Straighten connector functions
Connectors serve primarily as a visual aid for the programmer to show the
relationships among DDC functions in a drawing.
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 To straighten a connector
Do one of the following:
• Change shape on the drawing: Select the connector on the
drawing, click a center point, and drag it to the desired position.
• Use menu or tabs:
•
Visio 2007: From the VisualLogic menu, select Straighten
Connector, and then select Up, Down, Left, or Right.
•
Visio 2010: On the VisualLogic tab, select one of the Straighten
connector icons (up, down, left, or right).
Wrap Descriptor
The Wrap Descriptor feature of VisualLogic allows descriptions on drawings to
wrap rather than running on in a long single line after a function. This feature is
useful for long descriptions and keeps drawings tidier.
 To use the Wrap Descriptor feature
1. Select the function or functions for which you want to wrap long
descriptions.
2. Do one of the following:
• Visio 2007: From the VisualLogic menu, select Tools > Wrap
Descriptor (or press SHIFT+ALT+W).
• Visio 2010: On the VisualLogic tab, click Wrap Descriptor.
Alternatively, on the drawing, select the frame that contains the description text
(double-click the text) and drag the frame to the desired shape.
Creating program comments and generating a sequence of operations
VisualLogic has a program comment feature that you can use to document your
DDC operation. You can author any number of topics and associate them with
any range of functions.
The comments are saved to disk—and to the controller when sufficient memory
is available—along with the DDC file and the Visio drawing. A user or
developer can select a function and view comments about its operation.
You can save all comments for a drawing to a rich text file (*.rtf) and use it as a
source for creating a sequence of operations for your job. Topics are saved to file
in the order that they appear in the Program Comments dialog box. You can
adjust the order of topics.
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 To view comments
1. On the drawing, select the function for which you want to view
comments.
2. Do one of the following:
• Visio 2007 or Visio 2010: Right-click the function that contains the
comments that you want to view, and click View Comments.
• Visio 2007: From the VisualLogic menu, select Comments > View.
• Visio 2010: On the VisualLogic tab, click Comments, and then
select View from the drop-down list.
The Program Comments dialog box appears.
 To create comments for a function or range of functions
1. Do one of the following:
• Visio 2007: From the VisualLogic menu, select Comments > Edit.
• Visio 2010: On the VisualLogic tab, click Comments, and then
select Edit from the drop-down list.
The Program Comments dialog box appears.
2. Click Add.
A new topic with the title "New Comment" appears and is added to the
bottom of the list of topics.
3. In the lower field, replace the "New Comment" title with your own text
(the title automatically appears in the list of topic titles), and then type
comment text.
4. In the Range box, type the sequence number of the function or the
range of functions (separated by a dash, for example 10-100) you want
with which you want to associate this comment.
5. Optional: Click Font to select font styles, and then click OK.
6. Repeat steps 2-6 for each comment topic, and then click OK.
 To change the topic sequence
1. Do one of the following:
• Visio 2007: From the VisualLogic menu, select Comments > Edit.
• Visio 2010: On the VisualLogic tab, click Comments, and then
select Edit from the drop-down list.
The Program Comments dialog box appears.
2. In the Program Comments dialog box, select the topic title you want to
rearrange, and then click Up to move it toward the top of the list or click
Down to move it toward the bottom of the list.
N o t e Topics are saved to the *.rtf file in the order of appearance in the
list of topics. This order is independent of their assignment to function
sequence numbers.
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 To save all comment topics to a rich text format file
1. On the VisualLogic menu, point to Comments, and then click Edit.
2. In the Program Comments dialog box, click Save.
3. Select a folder and file name to save to, and then click Save.
 To change the font of a comment
1. On the VisualLogic menu, point to Comments, and then click Edit.
2. In the Program Comments dialog box, select the comment topic you
want to work with from the list.
3. Select the text that you want to change.
4. Click Font, and then choose font details in the box provided.
5. Click OK to apply the changes to the selected text.
Searching for an element
The Search tab (Figure 27) provides a means to search for—and if desired,
replace—specific elements in the current DDC.
Figure 27
VisualLogic Toolkit (Search tab)
The Search tab offers the following features:
• Specify objects to search: Select whether to search within selected
functions, on the current page, or all pages of the DDC.
• Find, replace all, or replace selectively: Allows control over find-andreplace feature.
• Match case: Narrows your search to capitalization as entered in the
Find point field.
• Recent searches: The drop-down lists in the Find point and Replace
with fields save the most recent entry. (Recent searches are cleared
when VisualLogic Toolkit is closed.)
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Viewing DDC statistics
The Statistics tab (Figure 28) provides the number of bytes and bits used for each
function on the current DDC.
You can use this information to help you modify your DDC if you go over your
byte/bit count for a VLC. (See Table 2 through Table 4 starting on page 13 for
byte/bit counts for VLCs.)
For Advanced VLC
files only, the
comment size is
shown separately
from other
information.
For all other file
types, the
comment size is
included in the
geometric
information size.
Figure 28
VisualLogic Toolkit (Statistics tab)
Note The bits and bytes used in a given function may differ depending on the
type of the global controller.
The Statistics tab offers the following features:
• Selectable controller type: Select the global controller from the VLC
type drop-down list.
• Printable: To print the table contents, click Print. VisualLogic
automatically prints the current contents of the table on the default
printer for the computer you are using.
• Errors and warnings: To view a list of errors and warnings for the
current DDC, click Refresh.
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• Size of comments (.bd6 files only): Shows the size of comments
associated with the DDC. Useful for deciding whether to save
comments from the Visio file (.vsd) to the compiled DDC file (.bd6) and
whether the send the comments from the DDC to the controller.
• Current and maximum file size: Useful for determining whether the
current file is nearing its maximum allowable size.
 To view DDC statistics
1. In the VisualLogic Toolkit, select the Statistics tab.
2. Click Refresh.
3. If a VisualLogic Errors dialog box appears, address each error and
warning, and then on the Statistics tab, click Refresh again.
 To update the table after changing the current DDC
Click Refresh.
Checking your drawing and viewing errors and warnings
Alerton recommends that you check your drawing before sending it to a
controller.
The Check Drawing feature on the VisualLogic Toolkit Errors tab searches your
drawing for common DDC programming errors, such as faulty I/O assignments,
duplicate sequence numbers, and the lack of the proper termination functions
(End of Normal, End of Subroutine).
The VisualLogic Toolkit Errors tab (Figure 29) presents a list of errors and
warnings associated with the current DDC.
• Error: Indicates that the DDC does not work. You cannot save the file
as a DDC, nor can you send it to a device. However, you can save the
file as a drawing. (See instructions under “Saving your work as a Visio
drawing” on page 34.)
• Warning: There is a nonstandard configuration or inefficiency in the
DDC. You can save the file as a DDC and send it to a device.
Figure 29
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The Errors tab offers the following features:
• Goto Error: To go to the function with the error or warning, select the
desired error or warning and click Goto Error. (Alternatively, doubleclick the desired item warning.) The toolkit opens the page on which the
problematic function appears, with the function automatically selected.
• Scrollable: Click Next Error or Previous Error to scroll through the
list of errors and address each one.
• Check Drawing: Regenerates the list of errors and warnings that occur
on all pages of the DDC. Click this button after you have made changes
to the current DDC.
• Provides descriptions: If tabs have different descriptions in the DDC,
the Errors tab presents as a warning.
 To check your drawing for errors and warnings
1. On the VisualLogic Toolkit, Errors tab, click Check Drawing.
The toolkit presents a list of errors and warnings.
2. As desired, select an error or warning (either by selecting it and clicking
Goto Error or by double-clicking it) and address the issue.
VisualLogic automatically opens the page on which the problematic
function appears with the function selected.
3. After you have made changes to the function, return to the Errors tab
and click Check Drawing again to confirm that the problem is
resolved.
Viewing live data
You can use VisualLogic to view values as they are processed in DDC. This is a
useful tool for testing and troubleshooting your DDC. VisualLogic traps data and
displays values beside the inputs and outputs on your DDC drawing.
When you load the drawing file, you can either read DDC from the device or
from a file on disk. You can view real-time data for a single function or any
number of functions. The speed of data updates depends on many factors:
network traffic and the number of functions you choose to view, for example. As
a general rule, choosing to view data for fewer functions results in quicker data
updates.
Steps
 To view real-time data in VisualLogic
1. Make sure the device you want to monitor is connected to the BACtalk
network.
2. In Visio, browse to and open the file that you want to work with.
• In Visio 2007: From the VisualLogic menu, select File > Open
Drawing.
• In Visio 2010: On the VisualLogic tab, click Open Drawing.
CAUTION Make sure that it is the same file loaded in your controller;
otherwise, erroneous data appears.
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Additionally, if you read DDC from a device or file and geometric
information was not saved to the device/file, DDC functions appear on
multiple pages in sequential order.
3. Select the functions for which you want to view live data values.
4. Open Live Data Options.
• In Visio 2007: From the VisualLogic menu, select Options > Live
Data Options.
• In Visio 2010: On the VisualLogic tab, click Live Data.
5. In the Device Instance dialog box, type the device instance of the
device that you want to monitor, and click OK.
Data from the controller appears in red beside its associated I/O
connector, as shown in Figure 30.
AV-62
60
sec
BV-26
on
Init-N
on
DOB
BR-0
on
BR-0
on
BR-1
on
3170
3160
Figure 30
Viewing live data on a DDC
Considerations
When viewing live data, keep the following considerations in mind:
• Values with the NOT or REV operation applied: When you view live
data (F2 View Data) in global or building controller DDC, values that
have had a NOT or REV operation applied may not display correct
values. VLCs show input and outputs values after the NOT or REV
operation is applied. Take care when interpreting these values.
• Building controller (.bd3 DDC) data within a subroutine: To view
live data in a global controller or building controller (.bd3 DDC) from
inside a subroutine, from the list under Live Data option, select the
desired subcaller sequence number.
• Difference between read and write present value for objects with a
priority array: When you write to a present value of an object with a
priority array, you write to Priority 9 or 14. However, the present value
may be overwritten higher in the priority array, resulting in a read
present value that is different from the write present value.
• Run-time Accumulator shows inaccurate output: The output of the
Run-time Accumulator does not reflect the true value of the assigned
AV. Instead, to read the true value, view the value of the assigned AV on
the input of a function.
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Setting VisualLogic Toolkit defaults
You can set default settings for the options in VisualLogic Toolkit Options tab by
editing the VisualLogic .ini file (vislogic.ini).
CAUTION Do not make changes other than those described in this section, and
do not make changes to other .ini files. Doing so can have unintended
consequences and can severely and adversely affect software performance.
The default installation path for the .ini file is:
C:\Alerton\BACtalk\<version>\Vislogic, where <version> represents the
currently-installed version.
VisualLogic Toolkit default settings are applied to the following files:
• New files that are created in VisualLogic.
• Existing files that have not yet been opened in the currently-installed
version of VisualLogic.
After a file has been opened in the current version of VisualLogic, the settings
made in the VisualLogic Toolkit remain with the file, and are automatically set
on the toolkit the next time the file is opened.
1
4
2
5
3
6
7
8
9
10
11
12
Figure 31
VisualLogic Toolkit (Options tab, setting defaults)
 To edit VisualLogic Toolkit default settings
1. Open the vislogic.ini file in Microsoft Notepad or another line editor as
desired. (See default installation path above.)
2. Make changes as desired.
Table 18 shows default settings as the software is shipped from the
factory. Unless otherwise indicated, options appear on the Options tab
in the location as shown in Figure 31.
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Ta ble 18
Default settings in vislogic.ini file
Line in file
Default
setting
splashbitmap=splash.bmp
n/a
Reserved. Do not change. Controls the
image that appears when VisualLogic
opens
rep=ALERTON
n/a
Reserved. Do not change.
job=STANDARD
n/a
Reserved. Do not change.
1
opt_senddescr=1
1
Selects (1) or deselects (2) the option to
include the descriptors when you send
the DDC file to the device.
2
opt_sendgeominfo=1
1
Selects (1) or deselects (2) the option to
include geometric information when you
send the DDC file to the device.
3
opt_sendcomments=1
1
Selects (1) or deselects (2) the option to
include comments when you send the
DDC file to the device.
4
opt_savedescr=1
1
Selects (1) or deselects (0) the option to
save descriptors from the Visio file to the
DDC file.
5
opt_savegeominfo=1
1
Selects (1) or deselects (0) the option to
save geometric information from the
Visio file to the DDC file.
6
opt_savecomments=1
1
Selects (1) or deselects (0) the option to
save comments from the Visio file to the
DDC file.
7
opt_autosequence=0
0
Selects (1) or deselects (0) the option to
enable autosequencing for functions that
are placed on a drawing.
8
opt_sequencestart=100
100
Sets the starting number for sequencing
functions that are placed on a drawing.
9
opt_sequencestep=10
10
Sets the interval between sequence
numbers.
10
opt_autoconnect=0
0
Selects (1) or deselects (0) the option to
enable autoconnect for functions that are
placed on a drawing.
11
opt_autoedit=0
0
Selects (1) or deselects (0) the option to
enable autoedit for functions that are
placed on a drawing.
12
opt_autopropagate=0
0
Selects (1) or deselects (0) the option to
enable automatic propagation of values
for functions that are placed on a
drawing.
opt_autobranchassign=0
n/a
Reserved. Do not change.
opt_validbranchrange=0-7
n/a
Reserved. Do not change
Purpose
3. Save the vislogic file and close the line editor.
Changes take effect immediately.
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Programming VLC DDC for the
BACtalk Microset and Microtouch
4
VLCs include built-in programming designed to work with either a Microset or a
Microtouch. Current heating and cooling setpoints are calculated automatically
based on occupied status, day and night setpoints, and heating, cooling, and
demand offsets. Management of the after-hours timer is also handled
automatically.
In addition, a reserved range of AVs and BVs for the Microset and Microtouch
enable customized control of the unit. These features greatly simplify DDC
programming for zone temperature control.
About the Microset
The BACtalk Microset is a microprocessor-controlled room sensor designed to
work with VLCs. It connects to the terminal labeled MSET (IN0) on the VLC. The
Microset enables an occupant to adjust the occupied setpoint, activate the system
after-hours, and view both the room temperature and the outside air temperature.
The Microset also includes a Field Service mode, which enables authorized service
personnel to view and change system operating parameters. The VLC
automatically detects when a Microset is connected to the appropriate terminal.
About the Microtouch
The Microtouch includes a 10K thermistor and a setpoint adjustment
potentiometer. The Microtouch must be connected to IN-0 and IN-1 (the first two
inputs) to function. The Microtouch allows the user to adjust the occupied setpoint
by moving a lever on the side to either increase (up) or decrease (down) the
setpoint. Pressing the center of the Microtouch during unoccupied hours activates
the after-hours timer. A jack is provided to allow connection of a field service tool.
Analog and binary values assigned to Microset and Microtouch operation
Every VLC has a range of data points (AVs and BVs) reserved for Microset and
Microtouch operation. Each data point has a particular function with respect to
Microset and Microtouch operations. Some provide feedback information (such as
room temperature); others enable control and interface with the unit. Table 19
summarizes these data points.
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Ta ble 19
VLC data points reserved for Microset and Microtouch
Object
Instance
Function
Remarks
AV-90
Setpoint (SP)
Displayed at the Microset and
adjusted up or down when the
WARMER or COOLER button is
pressed.
AV-91
Setpoint High Limit
The maximum value of AV-90.
AV-92
Setpoint Low Limit
The minimum value that AV-90.
AV-93
Cooling SP Offset
Used in the calculation of the
Occupied Cooling Setpoint (AV-99).
AV-94
Heating SP Offset
Used in the calculation of Occupied
Heating Setpoint (AV-100).
AV-95
Unoccupied Cooling Setpoint
The cooling setpoint used when
BV-67 is OFF.
AV-96
Unoccupied Heating Setpoint
The heating setpoint used when
BV-67 is OFF.
AV-97
After-hours Timer Limit
The adjustable override limit.
Maximum is 9.5 hours.
AV-98
After-hours Timer Value
The current value of the after-hours
timer. Automatically counts down
when after-hours operation is
enabled (BV-66).
AV-99
Current Cooling SP
Read only. Internally calculated
based on occupied mode, setpoints,
and offsets. (see “Setpoint
calculation” on page 76).
AV-100
Current Heating SP
Read only. Internally calculated
based on occupied mode, setpoints,
and offsets. (see “Setpoint
calculation” on page 76).
AV-101
Microset Room Temp.
The value displayed at the Microset
when the ROOM button is pressed.
Typically, this is used to display the
room temperature. AI-0 is the space
temperature input read from the
Microset, and DDC is written to
transfer the value of AI-0 to AV-101
for display.
NOTE: The Microset II displays as
“INSIDE” temperature.
AV-102
Space Humidity
Read only. If the Microset is
equipped with the humidity sensor
option, this AV provides the humidity
sensor reading in %RH.
AV-103
Outside Air Temp to Microset
The value displayed at the Microset
when the OUTSIDE button is
pressed. Typically, this is the outside
air temperature value, which is
transferred from elsewhere in the
system to AV-103 in the VLC.
NOTE: The Microset II displays as
“OUTSIDE” temperature.
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Ta ble 19
VLC data points reserved for Microset and Microtouch (Continued)
Object
Instance
Function
Remarks
AV-104
MicroTouch Lever Offset
Automatically calculated from
current lever position and the value
of AV-105.
IMPORTANT! AI-1 must be set to
Counts to get the correct readings
from the Microtouch lever settings.
AV-105
MicroTouch Lever Value
Maximum offset when lever is either
all the way up or down.
IMPORTANT! AI-1 must be set to
Counts to get the correct readings
from the Microtouch lever settings.
© Honeywell
AV-106
Demand Offset
Provides an interface for demand
limiting programs or other system
setpoint adjustment. Used in
conjunction with the setpoint (AV-90)
and heating and cooling offsets
(AV-93, AV-94) as appropriate to
calculate current heating and cooling
setpoints (AV-99, AV-100).
AV-107
Outside Humidity
If AV-107 is non zero, then the
outside air temperature (AV-103)
alternates with the AV-107 value.
BV-64
Time Schedule Output
Provides a system schedule
interface for setting occupied,
unoccupied operation. Write an ON
value to BV-64 to set occupied
operation, OFF for unoccupied
operation. (See “Occupied and
unoccupied modes” on page 77).
BV-65
Select ON-OFF Mode Enable
Enables occupant to manually force
unoccupied operation using the
Microset button. (See “Occupied and
unoccupied modes” on page 77.)
BV-66
After Hours Timer Status
Read only. ON when after-hours
operation is in effect.
BV-67
Occupied/Unoccupied Status
Read only except when BV-65 is
ON. ON = Occupied mode. OFF =
Unoccupied mode. Result of BV-64,
BV-65, BV-66.
BV-68
Field Service Lockout
Removes the ability to start Field
Service Mode from the Microset. ON
= Field Service Mode disabled.
BV-69
Swap English/Metric
Affects the Microset display only. ON
= Microset display is opposite of
English/Metric mode selection in
DDC header (see “AI setup” on
page 222).
BV-70
Microtouch (OFF)/
Microset (ON)
Read only. ON when Microset is
detected on AI-0.
BV-71
English (OFF)/Metric (ON)
Read only. Reflects English or
Metric selection in DDC header.
OFF = English. ON = Metric.
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Ta ble 19
VLC data points reserved for Microset and Microtouch (Continued)
Object
Instance
Function
Remarks
BV-72
Fan Low Speed
When BV-72 is set to ON, the fan
icon on the Microset II moves at slow
speed.
BV-73
Fan Medium Speed
When BV-73 is set to ON, the fan
icon on the Microset II moves at
medium speed.
BV-74
Fan High Speed
When BV-74 is set to ON, the fan
icon on the Microset II moves at high
speed.
BV-75
Door Open ICON
Reserved for future door open icon
on the Microset II.
BV-76
Fan Auto
Reserved for future fan auto icon on
the Microset II.
BV-77
Heating ICON
Display/hide heating icon on the
Microset II.
BV-78
Cooling ICON
Display/hide cooling icon on the
Microset II.
BV-79
Backlight ON
LCD backlight command on the
Microset II.
ON action/status -LCD backlight on
continuously.
OFF action/status -LCD backlight is
ON only in response to button
activity.
BV-80
Enable Fan Speed Control
Enable/disable fan control mode on
the Microset II.
BV-81
Select Hotel Mode
Select office mode or hotel mode
operation on the Microset II.
BV-83
24Hr Time Format
Select 12- or 24- hour time format on
the Microset II.
BV-84
Enable Space Humidity
Display/hide room humidity on the
Microset II. Applies only to units with
an optional humidity sensor.
Setpoint calculation
Throughout your DDC, use AV-99 and AV-100 for the actual current cooling and
heating setpoints, respectively. The VLC automatically includes offsets and
switches between occupied and unoccupied setpoints as appropriate. The
Microtouch lever offset is also automatically considered if a Microset is not
detected.
When the VLC is in unoccupied mode, it sets the current cooling (AV-99) and
heating (AV-100) setpoints to the unoccupied cooling (AV-95) and unoccupied
heating (AV-96) setpoints, respectively. When the VLC is in occupied mode, the
current cooling setpoint is set to the occupied setpoint (AV-90) plus the
Microtouch lever offset (AV-104, only included if Microset is not detected), plus
the cooling offset (AV-93), plus the demand offset (AV-106).
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Current cooling setpoint calculation
AV-99 = (AV-90) + (AV-104) + (AV-93) + (AV-106)
The current heating setpoint is set to the occupied setpoint (AV-90), plus the
Microtouch lever offset (AV-104, only included if Microset is not detected),
minus the heating offset (AV-94), minus the demand offset (AV-106).
Current heating setpoint calculation
AV-100 = (AV-90) + (AV-104) - (AV-94) - (AV-106)
Microtouch offsets
If a Microset is not detected, the VLC assumes a Microtouch is connected, and
input 1 is read as a Microtouch bias. The VLC calculates the Microtouch offset
(AV-104) based on the position of the lever and the Microtouch lever value
(AV-105).
Typically, when a Microtouch is used, the Microtouch lever value (AV-105) is
placed on a display to provide an easy way to adjust the amount of influence the
Microtouch lever has on the occupied setpoint. If the lever is in the full up
position, the Microtouch offset is a positive value equal to the Microtouch lever
value. Conversely, if the lever is in the full down position, the Microtouch offset
is a negative value equal to the Microtouch lever value.
As the lever is moved between the two stops, the Microtouch offset varies
between these two values. There are five possible values:
• Full up (+ AV-105).
• Partially up, midway between full up and the center position
(+ AV-105/2).
• Center position (with a value of zero).
• Partially down, midway between the center position and full down
(- AV-105/2).
• Full down (- AV-105).
I MP O R TA N T If neither a Microset nor a Microtouch is connected to the VLC,
set the Microtouch lever value (AV-105) to zero. If any other value is used, a
Microtouch offset is applied to the Occupied setpoint, depending on what, if
anything, is connected to input 1 on the VLC.
Occupied and unoccupied modes
The occupied mode of the VLC is controlled by BV-64, BV-65, and BV-66.
When BV-64 is activated, the VLC goes into occupied mode. The VLC remains
in occupied mode as long as BV-64 is ON, unless the OFF button feature is
activated (BV-65 is ON). When the OFF button feature is activated, the user can
press the OFF button to set the VLC to unoccupied mode. As long as BV-64 is
ON, the user can then toggle manually between occupied and unoccupied modes
using the Microset ON and OFF buttons.
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After-hours operation
When BV-64 is OFF, the VLC remains in unoccupied mode unless the afterhours timer (BV-66) is activated.
The value of the after-hours timer (AV-98) automatically counts down at a rate of
0.5 every 30 minutes until it reaches zero, at which time the after-hours timer
status (BV-66) turns OFF. The after-hours timer automatically resets to zero
when BV-64 turns ON. As long as BV-64 is OFF, the after-hours timer (AV-98)
can be manually adjusted in increments of 0.5 hours from a BACtalk data
display.
Microset
When a Microset is connected, the user can activate the after-hours timer by
pressing the ON button. For each press of the ON button, the after-hours timer
(AV-98) increments 0.5 hours, up to the after-hours limit (AV-97). Similarly, the
occupant can press the OFF button to decrement the after-hours timer in 0.5 hour
increments.
Microtouch
When a Microtouch is used, pressing the Microtouch center sets the after-hours
timer to the value of the after-hours duration (AV-97). The after-hours timer
status is ON whenever the after-hours timer is above zero.
Typical DDC for a Microset
Typically, a schedule in a global controller controls a BV object in the global
controller, which is then transferred to the VLC using global controller DDC.
The BV can be either directly transferred to BV-64 in the VLC to provide
scheduled zone operation or transferred to an intermediate BV in the VLC.
The Alerton Standard applications use an intermediate BV (typically BV-40) so
that this BV, or the warm-up BV or the cooldown BV, can be used to activate
BV-64, thus putting the VLC into occupied mode. This programming technique
can be used with the optimum start feature. This programming method also
allows you to independently adjust ventilation parameters depending on whether
the zone was put into occupied mode with a warmup, cooldown, scheduled
occupancy, or after-hours override command.
Heating and cooling control sequences can use AV-99 and AV-100 as the current
cooling and heating setpoints. These setpoints are automatically calculated as
described above depending on occupied mode status, offsets, and other factors.
BV-67 can be used as an indication of when the VLC transitions between
occupied and unoccupied mode. This can be useful for resetting Proportional
Integral (PI) functions when the setpoint changes.
Typically, a single VLC in a given installation has an outside air temperature
sensor. Global controller DDC is then used to transfer this value to AV-103 for
all other VLCs.
VLC DDC must be used to transfer the space temperature to AV-101. Typically,
the space temperature is AI-0, but in some applications you may wish to average
two or more sensors or use a different sensor. We recommend that you use
AV-101 as the space temperature throughout your programming; then if you
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want to change the sensor configuration you have to modify the DDC in only
one place.
The demand offset is included in the setpoint calculation to allow for the future
implementation of a demand limiting program. The demand offset is sent from a
global controller to AV-106.
The Microset present flag (BV-70) allows you to create display items that change
depending on whether or not a Microset is installed. The English/metric flag
(BV-71) allows you to write DDC programming that automatically adjusts
tuning parameters and limits depending upon the mode to which the VLC is set.
Field Service mode (MS-10xx)
The Microset can be used to access important control points within a VLC. If
BV-68 (Field Service Lockout) is OFF, it is possible to enter Field Service mode
by pressing the buttons on the Microset in a special sequence. The BACtalk
Microset differs from the IBEX Microset in that two Field Service modes are
available. Also note that the decimal point to the right of the Field Service codes
displayed at the Microset denote a default fixed code. Any custom codes that you
set up do not have a decimal point.
Pressing the button sequence BLANK-BLANK-ROOM-ON-WARMER on the
LED Microset (MS-10xx) allows access to the normal Field Service mode. The
Hot and Cold Flow CFM settings are read-only. The default fixed codes listed in
Table 20 are available in addition to any custom codes set up in the DDC header
(see “Microset Field Service mode custom codes” on page 225)
 To exit the Field Service mode
Press the blank button.
Alternatively, Microset automatically exits Field Service mode after 45
minutes of inactivity.
Ta ble 20
Default fixed codes for Microset Field Service Mode
Code
Meaning
Associated Data Point
UC.
Unoccupied Cooling Setpoint
AV-95
UH.
Unoccupied Heating Setpoint
AV-96
CO.
Cooling Offset
AV-93
HO.
Heating Offset
AV-94
CS.
Current Cooling Setpoint
AV-99
HS.
Current Heating Setpoint
AV-100
AL.
After-hours Limit
AV-97
HI.
Setpoint High Limit
AV-91
LO.
Setpoint Low Limit.
AV-92
SP.
Current Setpoint
AV-90
CF.
Cold Deck cfm (read only)
AI-10
HF.
Hot Deck cfm (read only). Dual
duct only.
AI-8
Custom codes can be entered in the DDC device settings header. You can assign
a custom code for up to 26 BI, BV, AV, BO, or AO objects.
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For each entry, you can specify whether the number appear with or without one
decimal place, and whether the item is read-only. Items can also be restricted to
positive numbers. For instructions, see “Setting up Microset field service codes”
on page 52.
Note If a BI, BV, or BO is specified, an ON value is represented on the
Microset as 1, and an OFF value is 0. Therefore, you must activate the decimal
point for binary items.
Balance mode (MS-10xx)
The button sequence BLANK-BLANK-ROOM-ON-COOLER on the LED
Microset (MS-10xx) enables a special VAV Box Balance Mode, which is used
for air balancing and airflow sensor calibration. This mode allows access to the
codes listed in Table 21 as well as entries 0–3 (for Microset v1.15) in the
Microset Field Service Mode Setup screen of VLC DDC (entries 0-4 apply for
Microset II v1.17). See “Setting up Microset field service codes” on page 52 and
“Microset Field Service mode custom codes” on page 225, for more information.
Ta ble 21
Additional default fixed codes for VAV Box Field Service Mode
Code
Meaning
Associated Data Point
HI.
Setpoint High Limit
AV-91
LO.
Setpoint Low Limit
AV-92
SP.
Current Setpoint
AV-90
SC.
Cold Deck Box Size
AV-250
SH
Hot Deck Box Size
(Dual Duct only)
AV-253
CF.
Cold Deck cfm
(Range is 0-32767) AI-10
HF.
Hot Deck cfm (Dual Duct Only)
(Range is 0-32767) AI-8
CF and HF (if applicable) show the current cfm, which can be adjusted by
modifying the calibration factor (k) during balancing. While in VAV Box Field
Service Mode, the WARMER and COOLER buttons change the k factor in
increments of ± 0.01, while the ROOM and OUTSIDE buttons change the k
factor in increments of ± 0.1. Using the VAV Box Field Service Mode, you can
adjust the k factor until the CF and HF readings match those from a balancing
hood.
Use VLC DDC to view the value of the k factor (see “Setting parameters for a
VAV airflow sensor” on page 227).
The following data points are available in VLC DDC, Alerton/Standard Device
Templates 82330000.DVT and 82340000.DVT and can be used to view and edit
balancing data.
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Air balance data points
Data
point
Description
Remarks
AV-250
Cold Duct Box Size
Range 0~63 inches
AV-251
Cold Duct Zero Velocity Cutoff
AV-252
Cold Duct Calibration Factor
AV-253
Hot Duct Box Size
AV-254
Hot Duct Zero Velocity Cutoff
AV-255
Hot Duct Calibration Factor
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Range 0~63 inches
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Programming techniques and
strategies
5
Direct digital control (DDC) programming underlies all operations performed at an
operator workstation. DDC ultimately drives all actions carried out by a user at a
data display or template. A DDC loop contains 10,000 sequential numbers of
locations in the range of 0 through 9999.
Useful tips
Programming DDC is a challenging undertaking and should not be attempted
without a thorough knowledge of Alerton systems and the equipment being
controlled. This chapter describes some common programming techniques and
strategies. Carefully plan and test your DDC program before implementing it.
Include Function 1: END OF NORMAL SEQUENCE
This is a common oversight. If you use subroutine DDC, make sure that you
remove the default function 1 at sequence 9999 and replace it at a sequence
number that marks the end of normal DDC. Otherwise, error messages appear.
Write separate DDC programs for devices on different networks
Even though BCMs are connected together in an array, you should always write
separate DDC programs to read/write data to/from VLCs connected to the MS/TP
network of each BCM (or to read/write data to/from TUXs connected to the TUX
trunk of each BCM-TUX). Basically, you should treat each BCM as a global
controller. Failure to do separate DDC can result in a serious degradation in
network communications and temporary communication delays of several minutes.
Do not write to a data point more than once
DDC won't tolerate multiple writes to data points. Doing so results in an error
message and DDC fails to execute. To make sure you aren't writing to these data
points more than once, use the cross-reference utility. Remember that if you write
to a data point in a subroutine, that data point is written to several times (once for
each sub-caller).
Note This applies only to objects without a priority array.
Leave room to grow
Space your sequences by at least 10—the first function at sequence 10, the second
at sequence 20, the third at sequence 30, and so on. The DDC Editor is set up to
facilitate sequencing by tens. Even though functions can be entered at every
sequence number, this enables you to add functions if you make a mistake.
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Plan before you program
Study the desired sequences of operations for the equipment to be controlled and
then create a DDC diagram for each sequence. Make sequences modular for
documentation purposes and ease of entry.
Document meticulously
As you develop the program, document the point assignments, starting with all
the physical control points at the VLC level. The control point list should include
all logical and physical points for VLC DDC. The control point list for global or
building controller DDC should include all points. Be sure to note the point type
(AI, BI, AO, BO, AV, BV) and whether any additional automated control
features are required (alarms, schedules, optimum start, for example).
Leave a written history of the assignment of inputs and outputs to equipment and
how control sequences were implemented. Document in such a way that another
engineer or programmer can decipher your work.
Save your DDC
Save your DDC to disk frequently to ensure that you don’t lose any information.
See “Saving your work” on page 33.
Test before equipment startup
As much as possible, test the control sequences you program before you actually
hook up equipment. Alerton advises that you use a test bench to simulate
equipment inputs and monitor outputs.
Use peer-to-peer DDC functions sparingly
VLCs that utilize peer-to-peer DDC functions (RED/WED) can generate a
significant number of broadcast messages on a BACnet network. Each RED/
WED function that references a device instance generates a BACnet WHO-IS
broadcast message every three minutes that the target device responds to with an
I-AM broadcast message. These messages are propagated throughout the entire
BACnet network. On a large network this can create additional unwanted traffic
and in some rare cases this traffic increase may overload the server.
Use peer-to-peer DDC functions sparingly and preferably only on small
networks (single subnets). Instead of using the RED/WED, consider using
REDS/WEDS. These functions are intended to support reading and writing to
BACnet slave devices (which rarely support BACnet WHO-IS, I-AM service)
but can also be used successfully without increasing broadcast traffic because
they locate devices by network number and MSTP MAC address, which
eliminates the need for WHO-IS/I-AM messages.
CAUTION When using either the REDS and WEDS DDC function, assign
network number 0 if the MS/TP device is on the local MS/TP network.
Note VLCs that support peer-to-peer DDC functions are limited to a maximum
of 15 RED/WED and REDs/WEDs functions.
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DDC download and start up
The DDC modification reported by the VLC is the date and time that the DDC
was last sent to the VLC. DDC operation is delayed on power up for 20 seconds.
This delay is intended to give the VLC time to communicate with the Microset
before DDC runs (for example, to get the current room temperature).
Assign all connections
All connections on functions must be assigned. Do not leave a connection
designated as “none.” When you check your drawing on the Errors tab of the
VisualLogic Toolkit, unassigned connections appear as an error (invalid DDC
function parameter).
For unused multiple input connections—such as for the Six-Input And Gate
function—it is acceptable to use multiple connections for the same input.
For unused output connections, programmers typically assign the output to
BR-0. Alerton recommends reserving BR-0 for unused outputs for functions.
Integrating with other applications using automation
Automation is a feature of ActiveX, which is Microsoft technology, and an
evolution of their component object model (COM) interface. For those who may
be familiar with dynamic data exchange (DDE) in IBEX systems, ActiveX in
BACtalk works much the same way. Other applications that support ActiveX can
use BACtalk's ActiveX Interface to fetch data from BACtalk while BACtalk is
running. The ActiveX Interface is, in fact, an Automation Object.
The BACtalk Automation Object essentially exposes BACtalk data so that it can
be used by scripts, programs, and applications that support Automation. This
enables you to read property values, write property values, and send a time sync
from another application.
Using the BACtalk Automation Object requires knowledge of object-oriented
programming techniques. To learn more, see the Alerton Support Network
(ASN): http://asn.alerton.com/s/Files/Resources/64840/?view=1. (Access to this
site requires a password.)
Using DDC to detect VLC communications failure
This section presents thee methods of using global or building controller DDC to
confirm communications between a VLC and a global controller and then
generating an alarm or another action in DDC if VLC communications is lost.
DDC is presented along with the advantages and disadvantages of each
approach.
Note EBT v1.3 and later includes a Comm Failure Object (found through
Device Manager) that can be used instead of DDC.
Method 1
The Delay on Make (DOM) and Delay on Break (DOB) functions in VLC DDC
combine to produce a pulse (BV-63) every 240 seconds. The Exclusive OR
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(XOR) function in the global controller DDC reacts to the pulse generated by the
VLC. As BV-63 switches from ON to OFF and back to ON, the XOR resets the
DOB, turning the VLC Comm Fail (BV-201) OFF. As long as the global
controller can read the pulse (BV-63) from the VLC, the XOR continually resets
the DOB. If communications between the global controller and the VLC fails, a
Comm Failure condition is reported through BV-201 after 900 seconds (15
minutes) have elapsed. This elapsed time is set using the delay input to the DOB.
The sequence numbering of the DDC functions in the global controller is very
important. Note that the XOR, at sequence 4500, executes before the Transfer
(XFR), at sequence 4510. This is the trick in getting the XOR to pulse ON to
OFF and repeat. Also, the branch point between the XFR and the XOR (BR-401)
must be a reserved branch point. This means that BR-401 cannot be referenced
anywhere else in global controller DDC.
Set up the VLC Comm Fail Alarm (BV-201) as you would any other binary point
alarm using the Alarm Wizard in BACtalk. The delay setting in the alarm point
setup should be set to zero so as not to conflict with the DOB in global controller
DDC.
Figure 32 Method 1: VLC and global controller DDC sequences for detecting VLC communications failure at the
global controller
Advantages and disadvantages The advantage of using this method over
Method 2 is that only one data point is being transferred between the VLC and
the global controller. The disadvantage is that the two timing functions in VLC
DDC consume RAM space, which may be needed elsewhere in the program
depending on the application.
Method 2
The Two-Input AND Function (&) in VLC DDC generates a pulse (BV-63) to
the global controller. BV-63 pulses between ON and OFF every time the global
controller transfers BV-63 to BV-62. As long as communication is established
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between the VLC and the global controller, BV-63 continually pulses between
ON and OFF. The Change of State Detector (COS) Function in global controller
DDC reacts to the pulse generated by the VLC. As BV-63 switches from OFF to
ON, the COS resets the Delay on Break (DOB), turning the VLC Comm Fail
(BV-201) OFF. As long as the global controller can read the pulse (BV-63) from
the VLC, the COS continually resets the DOB. If communications between the
global controller and the VLC fail, a Comm Failure condition is reported through
BV-201 after 300 seconds (5 minutes) have elapsed. This elapsed time is set
through the delay input to the DOB.
Set up the VLC Comm Fail Alarm (BV-201) as you would any other binary point
alarm using the Alarm Wizard in BACtalk. The delay setting in the alarm point
setup should be set to zero so as not to conflict with the DOB in global controller
DDC.
Figure 33 Method 2: VLC and global controller DDC sequences for detecting VLC communications failure at the
global controller
Advantages and disadvantages The advantage in using this method over
Method 1 is the Two Input AND function in VLC DDC does not consume RAM
space, which may be needed elsewhere in the program depending on the
application. The disadvantage is that two data points are being transferred
between the VLC and its global controller.
Method 3 (alternative)
Use this method to monitor the communication status of a non-Alerton BACnet
device.
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Figure 34 represents using Function 18: Two-Input Exclusive OR to detect a
non-Alerton device communications failure at the global controller (BCM or
VLX). Note the following:
• XOR is located in any BCM or VLX.
• Any valid binary point will work.
• BI/BV can be from any BACnet device.
Figure 34
Method 3: Detecting VLC communications failure.
See “Function 18: Two-Input Exclusive OR” on page 125 for more information
about Function 18.
Using DDC to detect communications failure in a global
controller (C3 VLCs only)
The Comm Fail flag in a VLC does not transition ON in a VLC when
communications with the VLC's global controller is lost. In fact, the Comm Fail
flag monitors whether the VLC passes the token on the MS/TP LAN. Two
VLCs—or any number of VLCs—without a global controller online pass the
token to one another as long as they can communicate. Therefore, the Comm
Fail flag does not transition ON until the VLC loses communication with all
other devices on the MS/TP LAN, not just the global controller.
As a result, the Comm Fail flag in the VLC is useful in DDC only insofar as it
enables VLC DDC to revert to a stand-alone mode of operation (for example,
causing setpoints to revert to stand-alone, default settings) in the absence of all
other devices, not just the global controller. It is not useful for determining
whether a VLC is online with a global controller, or whether global controller
DDC has halted.
To determine the status of global controller communications and DDC execution
reliably, a heartbeat DDC sequence in the global controller is necessary,
combined with a pickup DDC sequence in the VLC. The pickup DDC
effectively listens for the heartbeat and generates an output if it ceases. This
section presents DDC sequences for the global controller and VLC that generate
this effect. This is only one solution among many. You may find a more
appropriate or efficient DDC sequence for your specific application.
Note The VLC Comm Fail flag is set when communications have been lost for
five minutes and reset whenever a valid MS/TP message for the VLC is
received.
Explanation of DDC
The DDC sequences shown are for an global controller with Device Instance 211
and a VLC with Device Instance 702. It shows only the heartbeat and pickup
sequences.
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Global controller DDC sequence
The DDC sequence in the global controller uses Function 21: Anti Short Cycle
Relay to generate the heartbeat, which is written to the present-value of BV-10 in
VLC 702. The choice of BV-10 is arbitrary and could just as well be any other
property appropriate for your application. The output is written back to the input
and is negated. The Min. ON and Min. OFF values are set to 60 seconds. These
values determine how fast the heartbeat occurs. Without these values, BV-10
would toggle ON and OFF with each pass of DDC and quickly occupy
bandwidth on the MS/TP LAN. A minimum time of 60 seconds for these values
is recommended to keep MS/TP communications traffic down. Longer Min. ON
and Min. OFF values may be desirable.
Figure 35 Heartbeat generation sequence in the global controller using
Function 21: Anti Short Cycle Relay
VLC DDC sequence
In VLC DDC, the pickup sequence consists of Function 23: Change of State
Detector and Function 16: Delay on Make (DOM). Essentially, Function 23
picks up the global controller heartbeat signal (written to VLC BV-10) and feeds
it through a branch point (selected arbitrarily) into Function 16 (DOM). The
output of Function 16 remains OFF until communications is lost for 300
seconds, the Function 16 delay time. The output of Function 16, in this case
BV-11, is used in VLC DDC as a global controller communications failure flag,
which transitions ON if the global controller heartbeat isn't detected. Use the
Function 16 delay time to control the sensitivity of the sequence. This delay is
how long communications must be lost before the failure flag goes ON.
Figure 36 Pickup sequence in the VLC, which uses BV-11 (selected arbitrarily)
as the global controller communications failure flag
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Resolution of Microset-related AVs and use in DDC
Data resolution of Microset-related AV present-values is limited to increments of
0.5. As a result, using these values in DDC can have undesirable results.
Microset-related AVs are in the range AV-90 to AV-107.
Actual results depend on how Microset AVs are used in the control sequence. In
certain applications, AV-101 has been used as a space temperature input to the
proportional component of a proportional integral (PI) routine. AV-101 varied by
0.5 when the actual space temperature change was much smaller. This caused a
disproportional response and frequent equipment response, causing over cycling
of the controlled variable and possible premature wear on controlled equipment.
Do not use AVs 90-107 in control sequences where their limited resolution may
be an issue. Instead, use actual input values. For example, use AI-0 for space
temperature.
Understanding BACtalk PI and PID functions
Proportional Integral (PI) functions and Proportional Integral Derivative (PID)
functions in DDC (Functions 51 and 52) help control the balance between
environmental conditions and feedback in BACtalk systems to maintain zone
setpoints.
What is PID control?
The proportional, integral, and derivative components, when added together,
generate an output value in response to a feedback input and setpoint. The output
of the function varies in an attempt to get the feedback input to match the
setpoint. In HVAC applications, the feedback input is often a temperature, such
as a room temperature, and the setpoint is the room setpoint. The output is then
used to control a damper, valve, or cycling time of heat stages. The proportional
component responds instantly to changes in the feedback input or setpoint, while
the integral component responds gradually over time. The derivative component
is based on the rate of change of the feedback input relative to the setpoint.
PID logic has been used with industrial controls for a long time. The Alerton
BACtalk PI and PID controllers use industry-standard terminology wherever
possible.
PI versus PID
For virtually all HVAC applications, it is generally wiser to use PI control rather
than PID control. The Derivative component generally does not add much
responsiveness, and it can be difficult to tune. Erratic response often results from
using Derivative control in HVAC applications. Although PID control is often
included as a specification requirement, the Derivative component should
probably not be used unless you are very confident in your understanding of the
complexities of tuning PID controllers.
How is the output of the PI function calculated?
The output of the BACtalk PI controller is the sum of three factors: proportional
component (P), integral component (I), plus a constant of 50. The output is
limited to a range of 0 to 100.
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Output = 50 + P + I
The primary inputs are the setpoint (SP) and feedback input (FB). The other
inputs are tuning parameters, and they are generally set to fixed values as needed
to achieve responsive yet stable control. Both the P and I components are
calculated from the difference between the setpoint and the feedback input. This
difference is called the error (E), and it represents how far away from setpoint
the feedback input is.
E = FB - SP
The goal of the control function is to get this error value to go to zero (that is,
feedback input = setpoint.)
The proportional component responds instantly and is simply proportional to the
value of the error. The only tuning parameter that affects the proportional
component is the proportional constant (Kp). The proportional component is
equal to the error times the proportional constant.
P = E x Kp
The integral component is calculated as a running total over time. It is used to
make incremental adjustments over time to get the feedback input to match the
setpoint. When the function is first started, the integral component is set to the
value of integral startup (STUP). From then on, the integral component is a
running total, with an integral adjustment value added every second. The integral
adjustment value that is added each second is the error times the integral
constant (Ki) divided by 60. The integral constant is divided by 60 since it
represents the change per minute, and the calculation is performed every second.
I = Iprevious + (E x Ki /60)
The integral adjustment value is limited by the maximum integral change (Imax),
which is the maximum amount the integral component is allowed to change per
minute. The maximum allowed integral adjustment (which is added once per
second) is then Imax/60.
Finally, the value of the integral component is limited by the integral limit
(Ilimit). I is not allowed to be greater than Ilimit or less than -Ilimit.
|I| < Ilimit
Reversing the output for reverse acting applications
The default output action of the proportional integral functions is direct acting
(DA). As the feedback input increases, the output increases. Likewise, when the
feedback input decreases, the output decreases. Some applications require the
PID controller output to be reverse acting (RA); as the feedback increases, the
output decreases. Likewise, when the feedback decreases, the output increases.
For RA applications, use the REV feature of DDC on the output of the function.
When this is done, the Reversed Output = (100 - Output).
Direct acting (DA) output is appropriate for the following applications:
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• Normally open (NO) heating valve.
• Normally closed (NC) cooling valve.
• Building static pressure control (relief damper or variable frequency
drive).
• Economizer dampers where the outside air (OA) damper is NC
Reverse acting (RA) output is appropriate for the following applications:
• Normally closed heating valve (steam for instance).
• Normally open cooling valve.
• Supply duct static pressure control (inlet vanes or variable frequency
drive).
• NC steam humidifier valve.
• NO relay contacts serving electric heating coils.
Setting the tuning parameters
Tuning a controller has always been a bit of an art. Experimentation is usually
necessary to achieve optimum performance. Increasing the values for Kp and Ki
increases the responsiveness of the BACtalk PI controller, but reduces the
stability. The goal is to get the controller to provide the most responsive control
possible without hunting.
One of the challenges in tuning PI loops in HVAC control is that system
response functions vary considerably depending on circumstances. For example,
when controlling an economizer damper to maintain a desired supply
temperature, the effect of modulating the damper is very different when the
outside air temperature is 0°F versus 50°F. For this reason, it is generally best to
tune loops conservatively. This slows response but helps ensure stable control
over all operating conditions. Be sure to consider the effect of the current and
possible operating conditions when tuning a loop.
Proportional constant (Kp)
This constant adjusts how responsive the proportional component is to
differences between the feedback input and the setpoint. A larger value for Kp
increases the influence of the proportional component.
I MP O R TA N T Proportional constant is the amount the output changes in
response to a change in the error value equal to one.
A typical value for Kp for room temperature control applications would be 12.0
for English unit applications. This means that if the room temperature (feedback
input) is 76° and the Setpoint is 74°, the proportional component would be 2 x
12.0 = 24. If the integral component was zero, the output would then be 50 + 24
= 74.
When it takes a long time for the feedback input to change once the controlled
item is adjusted (for example, when modulating a VAV cooling damper to
achieve a desired room temperature), it generally reduces the value of Ki relative
to Kp. The proportional constant often helps prevent overshooting in these cases.
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When the feedback input responds quickly to changes in the controlled item (for
example, when modulating a damper to achieve a desired airflow), the
proportional constant should generally be set fairly low, perhaps even to zero,
leaving most of the control to be performed by the integral component.
To determine an appropriate initial value for Kp, divide 3 by the smallest amount
you would typically adjust the Setpoint. For example, for controlling a supply
fan speed to maintain duct pressure, the smallest setpoint adjustment would
probably be 0.1. Thus, the starting value might be 3/0.1, or 30. You will of
course have to use your judgment as to whether to adjust this value up or down
depending on the stability and responsiveness of what you are controlling as well
as the consequences of overshooting the value.
One disadvantage of the proportional component is that it instantly responds to
any change in the feedback value, which can result in subtle hunting or excessive
minor adjustments to a damper or valve, even when the feedback is near
setpoint. In some cases, it is better to use only the integral component (Kp = 0) to
prevent this problem. Another option for solving this problem is to set the
feedback input of the PI function to the setpoint when the actual feedback value
is acceptably close to the setpoint. For an example of this, refer to the damper
control logic used in the Alerton Standard VAV applications.
Integral constant (Ki)
This constant adjusts how responsive the integral component is to differences
between the feedback input and the setpoint. A larger value for Ki increases the
influence of the Integral component.
I MP O R TA N T Integral Constant is the amount the Output changes over the
course of one minute, in response to an error value equal to one.
Typically, the initial value calculated above for Kp represents a reasonable
starting point for Ki, Divide 3 by the smallest amount you would typically adjust
the setpoint. When the feedback input responds quickly to changes in the
controlled item, the integral constant should be set much higher than for slower
response applications like room temperature control.
A typical value for Ki for room temperature control applications would be 1.0.
This means that if the room temperature (feedback input) is 76° and the setpoint
is 74°, the integral component would increase by 2.0 every minute (provided
Imax is greater than 2.0).
When modulating a damper to obtain a desired airflow, a good starting point is
Ki = 100/FBrange where FBrange, is the full range you would expect for the
feedback input as the control output varies between 0 and 100. This is a
reasonable starting point for applications where the feedback responds almost
immediately to changes in the actuator position.
Maximum integral change (Imax)
This constant limits the rate of change of the integral component. The integral
component is not allowed to change faster than Imax per minute, or Imax /60 per
second.
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I MP O R TA N T Imax represents the maximum amount of change allowed for the
integral component in one minute.
Typically, Imax should be set to match the speed of the actuator being controlled.
It should equal the percentage of full stroke that can be achieved in one minute.
For example, if a VAV damper is being controlled, either to achieve a desired
room temperature or to achieve a desired airflow, and the full stroke damper time
is 5 minutes, then Imax should be set to 20. This is because the damper can only
stroke 20% of its full stroke in one minute. As another example, if a valve can be
actuated in 30 seconds, then Imax should be set to 200, since the valve can stroke
200% in one minute.
Integral limit (Ilimit)
This constant limits the value of the integral component to ± Ilimit. It is used to
limit the integral contribution allowed in the overall control signal. It is typically
set to 50 which allows the integral component to bias the output to anywhere
between 0 and 100 when the feedback input equals the setpoint (which by
definition makes the proportional component equal to zero).
If you use a number greater than 50, the output could potentially stay fixed at 0
or 100 for a while, even when the error indicates a need to adjust the output in
the opposite direction. The industry term for this phenomenon is “integral
windup.” It can be useful for certain applications when you want the integral
component to be able to build up. Building up the integral component delays any
change from 0 or 100 (depending on whether the integral component is negative
or positive).
Integral startup (STUP)
This constant is used to initialize the value of the integral component upon
startup. Also, the integral component is set to this value whenever Ki is set to
zero. This is useful for resetting the integral component upon a change in
setpoint or when starting equipment such as a fan. It is generally good practice to
momentarily switch Ki to zero upon a change in setpoint or when starting the
controlled equipment to reset the integral component.
Upon initialization (or when Ki is set to zero), the Integral component equals
STUP. For applications where the Kp is equal to zero or when the Feedback
Input happens to match the setpoint, the output is equal to 50 plus STUP upon
initialization.
You can calculate a good value for STUP by subtracting 50 from the output that
you want upon startup. For example, if you want the output to start at 20, set the
STUP to -30 (50 + -30 = 20).
Be careful in applications where the output is reversed. For example, consider an
application where you are controlling fan speed to achieve a desired duct
pressure. The output would be reversed and, upon startup, you may want the
output to be about 20%. This means that you want the normal (not reversed)
output to be 80. If Kp is equal to zero (not a bad idea for fan control), the normal
output upon initialization equals 50 plus STUP. If you want an initial value of 80,
set STUP to 30. The reversed output is then set to 20 upon initialization.
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Proportional constant versus throttling range
Many control engineers who are used to working with pneumatic controls or the
Alerton receiver controller are used to setting the proportional response by
adjusting a throttling range. Increasing the throttling range actually decreases the
responsiveness of the controller, while increasing the proportional constant (Kp)
increases the responsiveness of the controller.
For example, consider an application where you are controlling a VAV damper to
achieve a desired room temperature. If the throttling range is set to 5, the damper
is adjusted from fully closed to fully open as the input varies from 2.5 degrees
below the setpoint to 2.5 degrees above the setpoint. To determine the
corresponding value of Kp, you simply look at how much you want the output to
change for every degree of change in the Input. In this case, it is 20.
A simple way to convert throttling range to Kp is to use the formula: Kp = 100/
Throttling Range.
Bit-packer and bit-unpacker DDC
Envision for BACtalk does not have bit-packer and bit-unpacker DDC functions.
For this reason, Alerton developed the bit-packer and bit-unpacker DDC routines
discussed here. The bit packer and unpacker DDC is contained in a VisualLogic
file. Page 1 is the bit-packer DDC. Page 2 is the bit-unpacker DDC. This file is
located on the Alerton Support Network under Applications > BACtalk >
Miscellaneous.
Primarily, these DDC routines enable integration of a BACtalk system and thirdparty devices that write or read multiple bits in a single control point. Some
manufacturers use a single 8-bit or 16-bit number to issue up to 16 different
digital commands. The number of bits used is dependent on the manufacturer.
Each bit in the number represents a different command. For example, you can
use this DDC to integrate your BACtalk system with a Modbus VFD, which may
use a single register/coil address to represent multiple points, each point
represented by a bit in the register/coil address number.
Once you understand the DDC routines, you can scale them to manage only the
number of bits you need to work with.
Bit-packer DDC routine
The bit-packer DDC routine encodes an 8-bit number as 8 BVs (as written, BV-0
through BV-7).
The DDC assigns the appropriate value to each BV and writes the output value
as AV-0, including DDC to write only on change-of-state. For example, turning
BV-4 ON activates a Function 40: Switch to pass the value of 16 (BV-4
represents the 16's position) to a Function 33: 6-input Addition. The 16 is then
added to any other bit values that have been set to ON. As written, any number in
the range 0 (all BVs OFF) to 255 (all BVs ON) is possible.
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Bit-unpacker DDC routine
The bit-unpacker DDC routine does just the opposite of the bit-packer routine. It
reads an analog value (as written, AV-0) and unpacks that value into eight binary
values, each representing a bit (as written, BV-0 through BV-7).
The bit-unpacker DDC has a three-function, bit-checker DDC sequence for each
possible bit in the value. Each sequence consists of a Function 39: Within,
Function 30: Subtraction, and Function 40: Switch. Beginning with the largest
possible bit-value, the bit-checker sequence reads the value from the register coil
address and checks to see if it is within a specific bit range. If the bit-encoded
value is detected within the analog value, the bit-checker sequence sets the BV
representing the bit to ON, subtracts the bit value from the total value, and then
passes the reduced value to the next bit-checking sequence. The process repeats
for all bit-encoded values to be checked.
Migrating IBEX global controller DDC to the BCM-TUX
The BCM-TUX serves as a global controller for all TUXs connected to its TUX
trunk. If you upgrade an existing IBEX site with the BCM-TUX, you need to
write global controller DDC and set up control features in the BCM-TUX to
replace the functions formerly provided by the IBEX global controller, such as
an APEX or APEX-LT.
I MP O R TA N T Understanding how to set up and program the BCM-TUX to
properly control the connected TUXs first requires that you have a solid
knowledge of how BACnet virtual devices are used to represent the TUX on the
BACnet network. See the BACtalk Control Modules Installation and Operations
Guide (LTBT-TM-BCMIOG) for details.
Alerton has provided a library of subroutines designed to replace the APEX
DDC library that is included with IBEX systems. This library is available for
download on the Applications & Tools page of the ASN.
Dedicate BCM-TUX programming to connected TUXs
Each TUX trunk physically requires a dedicated BCM-TUX. Similarly, the
programming and automation features in each BCM-TUX should be devoted
exclusively to the TUXs on its TUX trunk. Doing so improves performance and
system stability.
CAUTION Do not host DDC and automation for devices on several TUX
trunks in a single BCM-TUX. The increased communication load between
modules compromises system performance.
For example, if you replace a fully-loaded APEX with four BCM-TUXs, you
must split the DDC program into four separate programs: one for each BCMTUX. Similarly, set up alarms and trendlogs in a BCM-TUX only for directly
connected TUXs, where the alarmed or trended data originates.
No TUX DDC editing capability from a BACtalk system
BACtalk operator workstation software provides no facility for editing TUX
DDC. Therefore, if you connect a programmable TUX to a BCM-TUX, ensure
that you retain some method of connecting to the programmable TUX. If the
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TUX has a direct connect header, TDS with an AC-2650 cable can be used to
view or edit programming. If the TUX doesn't have a header, an IBEX global
controller or a TID must be used to connect to the device to view or edit
programming.
IBEX control strategies compared to BCM-TUX control strategies
The table in this section identifies functions and features performed by the global
controller in an IBEX system and how similar functions can be achieved using
the BCM-TUX
Ta ble 23
Functions and features performed by the global controller in an IBEX system
Function/feature
IBEX system approach
BCM-TUX approach
Schedule operation of a
TUX
Typically this was done in an IBEX
system by linking a control panel to the
TUX and transferring the Zone Generic Day point to the appropriate TUX DO
(typically DO-3) in subroutine DDC.
There are two options for scheduling TUX operation.
If you want to use the optimum start
feature, you use subroutine DDC to
transfer the Zone Generic - Warmup and
Cooldown points to the appropriate TUX
points.
The first option is to set up the appropriate BO
(typically BO-3) in the virtual device representing the
TUX as a scheduled point in BACtalk. The second
option is to set up a zone object, using the virtual
device as the zone device reference and using the
appropriate BO as the Occupied Command.
The second option also allows you to use the
optimum start feature of the zone object. When
setting up the zone object, set the warmup and
cooldown commands to the appropriate BOs in the
TUXs virtual device. You must also specify
appropriate values or data locations for the other
optimum start parameters.
Enable heating, cooling, and
unit operation
Some application specific TUXs require
that ON values be sent to DOs. This is
done in APEX DDC.
Use BCM-TUX DDC to write to appropriate BOs in
the virtual device. See the installation and operations
guide for the specific TUX at hand for a data point
reference. Typically BO-1, BO-2, and sometimes BO8 are used.
Enable expanded mode
Use Device 79.
Expanded mode is automatically enabled in the
BCM-TUX and no action is required.
Important! The BCM-TUX does not support 1200
baud TUX trunk communications.
Trend a data point
Use IBEX trendlogs.
Any virtual device points can be trended using
Envision for BACtalk trendlogs.
Alarm a data point
Use IBEX alarms.
Any virtual device points can be alarmed using
Envision for BACtalk alarms.
Programming with Zone
Custom points
IBEX allows you to use APEX DDC to
generate values for Zone Custom points,
which can then be placed on a control
panel template. (This is part of the
control panel concept.)
There are AVs and BVs available in the virtual
devices that are not mapped to specific TUX points.
These can be used in DDC programming in a similar
method to Zone Custom DDC. These points can be
placed on a device template, similar to the way zone
custom points are placed on a control panel template.
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Ta ble 23
Functions and features performed by the global controller in an IBEX system (Continued)
Function/feature
IBEX system approach
BCM-TUX approach
Programming with Zone
generic points
Use Zone generic points.
Zone generic- Day, Warmup, and Cooldown are
covered earlier in this table. Space temperature, day
heating, and day cooling are replaced by setting up
the optimum start configuration of a zone object, (no
DDC necessary). Shed and Shed bias are replaced
by demand limiters in BACtalk. Note that demand
offset in a TUX is sent in counts rather than degrees.
One count is roughly 0.5 degrees F. User Low, User
High, User Unit Alarms, Zone Generic User Alarms,
and Zone Generic SA Alarms have no equivalent in
BACtalk. Alarms are configured individually in
BACtalk. You could potentially write DDC to calculate
an alarm value, up to five possible values including
normal, and use an analog display item with 5
different bitmaps to indicate which alarm is present,
but this would be time consuming. Run-time ON and
Run-time Hrs/10 are not necessary since global
controller DDC includes a run-time accumulator
function.
Allow use of TUX values in
control panel DDC
Use Zone TUX points.
Global controller DDC allows this through use of the
Set context function.
Data display re-use
Use Control Panel templates.
Use Device templates.
Convert pulse data
APEX DDC allowed use of Device 9 to
convert compound data (AI-1 through AI6) from a TX-651-Pulse to both
consumption and rate.
Pulse count and pulse width can be converted to
consumption and rate using DDC math functions in
the BCM-TUX.
Pulse width comes from the TUX in tenths of a
second (AI-11 through AI-16). These values can be
converted to a rate by taking the reciprocal and
multiplying by 10 times the amount per pulse. This
gives a rate in units per second. Multiply this value by
60 to get rate per minute or 3600 to get rate per hour.
Pulse counts (AI-21 through AI-26) may be multiplied
by the pulse value to yield consumption.
The gateway string may also be used to convert data,
but this adds complexity and should be avoided.
Make data available
throughout the system
Use global points.
No action required. BACnet data can be seen from
anywhere on the network.
Control panel subroutines
TUX is linked to control panel using
Device 80.
Function 67: Subroutine caller allows reference to a
changing device in subroutine DDC.
Copying descriptions to another controller
There are two methods for copying descriptions from one controller to another.
• Using BACtalk Builder
• Using Device Manager
Using BACtalk Builder
Alerton recommends using BACtalk Builder to copy descriptors from one
controller to another for the following reasons:
• The Device Manager method does not copy the unique device instances
that are required by newer controllers that support multistate values.
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• BACtalk Builder supports all VLC and Advanced VLC controllers.
• The BACtalk Builder method is automated and not prone to errors.
BACtalk Builder can be used to copy descriptors to pointdata.mdb (commonly
called point data) for all controllers.
For information about using BACtalk Builder, see the section on copying point
data in BACtalk Builder User’s Guide (LTBT-BBOPMAN), available on the
Alerton Support Network.
Using Device Manager
Descriptors for AI, AO, BI, BO, AV and BV objects in Gen4 VLCs are
optionally embedded in the DDC file and downloadable with DDC or writable
using BACnet messaging.
For example, you can change these descriptors using a prompted property on an
operator workstation display. This allows you to make changes to descriptors
without having to resend DDC. This can be useful when you do not want to give
DDC privileges to users, but you do want to allow them to customize
descriptors. This also allows you to use the same DDC file for multiple
controllers, even if they have different uses for outputs that are not referenced in
the DDC file.
For example, if you want to use a spare output on a VAV controller to control an
outside light, you could control it directly with a schedule or global controller
DDC and change the descriptor for that BO on that particular controller without
having to create a special DDC file that is otherwise identical.
Revised VLC device templates that include point descriptors as prompted
properties are available on the ASN. This provides one method for entering
descriptor properties. If you wish to copy descriptors from one controller to
another (for example, when controllers have identical DDC, descriptors, and
present values as defaults), use the following procedures.
 To copy descriptions from one controller to another controller
1. Enter the descriptors for a VLC using VLC device templates.
2. Use Device Manager to save point data from the VLC. Be sure to select
the present values, priority arrays, and the relinquish defaults box.
3. Create folders (unless they already exist) for all VLCs that you wish to
copy descriptors to.
Manually create these folders or have Device Manager automatically do
it for when you save point data from the controllers.
The folders must reside in the same rep/job folder as the job you are
working in and should be named DEVnnnnn (where nnnnn is the device
instance). If the device instance is longer than five numbers, truncate
the DEV portion as needed to allow numbers to be in the name. Folder
names cannot exceed eight characters.
The process is faster if you choose to save only the VAV calibration
factors (even if the VLCs are not VAV controllers).
4. Copy the PointData.mdb file from the folder corresponding to the VLC
in steps 1 and 2 to all the folders created in step 3.
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5. Use Device Manager to send point data to all the VLCs to which you
want to send descriptors. Select the present values, priority arrays, and
relinquish defaults box.
Ca ution This changes all point data to match the original controller
from which you saved data. This includes the following:
• All present values for set points (AV, AO, BV, and BO).
• VAV controller cold deck parameters AV-64 Motor Time, AV-66
Reheat Flow, AV-67 Max Flow, AV-68 Min Flow, Hot Deck
parameters AV-65 Motor Time, AV-71 Min Flow, and AV-73 Max
Flow.
Do not select the VAV calibration factors, box sizes, or zero cutoffs box.
Writing object names and descriptions to Gen4 devices
This section describes how the object name and object description properties are
handled, depending on the real-time operating code (ROC) that is installed on a
device.
All Gen4 VLCs support ROC file 4.10b4. No other devices support this ROC
file.
Note The VLC-444, VLCA-1688, VLD-362, and MS/TP Microset II
controllers each have a distinct ROC file.
How objects are defined
Objects are identified by the following properties:
• Object identifier: Not editable. Consists of an object type (such as AI,
BO, or AV) and an object instance (identified as a numeral). Examples
include BO-16 and AI-02.
• Object name: For ROC versions 4.10b4 and later, editable for all Gen4
devices. By default, consists of the object type and the object instance,
separated by a space, such as BO 16 and AI 02.
Microset and Microtouch exceptions: Points AV-90 through 107 and
BV-60 through 84 are defined as though they were descriptions. As
examples, the default object name for AV-90 is Setpoint (SP), and the
default object name for BV-64 is Time Schedule Output.
• Object description: Editable for supported devices. Usually a
descriptive text string, such as Lunch room cooling setpoint.
Figure 37 shows how the object identifier, value, object name, and object
description are shown in the Envision for BACtalk user interface. The top image
shows a VisualLogic controller’s analog inputs, and the lower image shows a
VisualLogic controller’s Microset/Microtouch points.
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Object name:
Editable. The
default format is
the object type, a
space, and the
object instance,
such as AV 90.
(See Microset and
Microtouch
exceptions above.)
Object
description:
Editable. Usually
a descriptive text
string (such as
Lunch room).
Current
value
Object
identifier: Not
editable.
Consists of
object type
(such as AV)
and object
instance (such
as 90).
Figure 37
Object properties in Envision for BACtalk interface
Beginning with the release of VLC ROC 4.10b4, you can use both the object
description property and the object name to label points.
Differences between Gen4 ROC versions
Depending on the version of the ROC file that is loaded on a Gen4 VLC, the way
description and object name properties are handled is different, as shown in
Table 24.
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Ta ble 24
Differences between ROC versions
ROCs earlier than 4.10b4
ROCs 4.10b4 and later
Object names
Has fixed text strings in the
object name property that
cannot be edited.
Has editable object name
property of AI, AO, AV, BI, BO,
and BV objects. To edit, use the
prompted property of a display.
DDC selected in
Writable/DDC
option in Device
Settings
Descriptions are in DDC.
Descriptions are in DDC, but
can be overridden from any
Envision for BACtalk display
that shows them.
They can overridden only if
they are re-edited using
VisualLogic or the Envision for
BACtalk DDC editor.
Descriptions that are present in
the DDC file are used as default
if the user has not overridden
them by assigning other
descriptions from Envision for
BACtalk.
Writable selected
in Writable/DDC
option in Device
Settings
Descriptions that are contained
in the DDC file are ignored.
Descriptions that are contained
in the DDC file are ignored.
Descriptions are either defined
manually or via BACtalk
Builder’s Point Builder and then
loaded on the controller by
sending Point data, as
described on page 98.
All descriptions can be edited
from Envision for BACtalk
screens.
Flash memory
Contains only description
strings, so there is enough
room for a 38-character
description for every object on
the VLC.
Shared between assigned
object descriptions and object
names. Consequently, there
may not be enough room for
every object to have an
assigned description.
Text strings are limited to 30
characters.
ROC versions earlier than 4.10b4
If a VLC has a ROC earlier than 4.10b4 installed, an object’s name is not
editable.
To label a point you must edit the point’s description property. Editing is
controlled in Device Settings on the General tab (Figure 10 on page 38) in the
Writable/DDC Descriptions field.
For ROC versions previous to 4.10b4, an area of flash memory is reserved to
accommodate a 38-character description for each of the AI, AO, AV, BI, BO, and
BV objects.
Object descriptions can also be assigned in the DDC and stored as part of the
DDC file. A configuration selection in the DDC header determines which of the
descriptions is used.
Writable
If Writable is selected in the Writable/DDC Descriptions field, the descriptions
that are stored in flash memory are used. An object description shown on an
Envision for BACtalk screen can be edited and saved at the VLC.
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Use Device Manager to save descriptions from the VLC to the devices
pointdata.mdb file, or conversely to download descriptions from the devices’s
pointdatat.mdb file to the VLC.
Note Alerton recommends the Writable setting for devices loaded with a ROC
earlier than the 4.10b4 version. This setting allows users to update descriptions
from a prompted property on a display. (If the option is set to DDC and the
descriptions are not defined in Device Settings, descriptions that you send to
controllers via Device Manager, Send Point Data are not visible. If DDC is
selected and you do not define any descriptors, you cannot load descriptors from
the pointdata.mdb file. Also, only VAV applications in Alerton/Standard have
point descriptions defined.)
DDC
If DDC is selected in the Writable/DDC Descriptions field, point descriptions
reside in the VisualLogic DDC file that is loaded on the device. Description
properties cannot be edited from Envision for BACtalk screens.
Instead, edit the point description properties in the DDC by using VisualLogic on
the Point Setup tab. (To populate the Point Setup tab, click Collect Points (for
.bd4 files) or Synchronize Points (for .bd6 files).) See instructions under “Setting
point descriptions” on page 43.
Note You can also edit DDC descriptions by using the DDC editor that is
included with Envision for BACtalk. (For more information, see “DDC editors”
on page 11.)
ROC versions 4.10b4 and later
If ROC version 4.10b4 or later is installed on a supported device, you can use
both the object description property and the object name property to label points.
Benefits
This section describes the merits of being able to edit the description and object
name properties.
Using Object Scanner Being able to edit a point’s object name enables you to
use Envision for BACtalk’s Object Scanner (found on the Envision toolbar under
Tools > Advanced > Object Scanner) to perform a global interrogation of a
system.
The Object Scanner function enables you to search a BACnet system to discover,
view, or edit one or more objects.
For example, if you scan a BACtalk system for all points with an object name
property of space setpoint, Object Scanner returns all points with that object
name, along with each point’s present value. You can then edit the present value
of one or more of those points with one simple command.
With the installation of ROC 4.10b4, Object Scanner becomes a powerful and
useful tool for starting up and commissioning a system, for troubleshooting, and
for helping in the operation and energy management of a building.
Downloading descriptions with DDC When you load the same DDC into
many devices, all of the object descriptions are also downloaded with the DDC.
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If objects descriptions are not included with the DDC, you must do one of the
following to edit them:
• Edit the object descriptions on each individual device.
• Copy a pointdata.mdb file and use Device Manager to download the file
to each VLC.
• Use BACtalk Builder/Point Builder to edit and copy descriptors to
devices and then save to pointdata.mdb.
Note Available text strings are used when descriptors are not defined in DDC
and you load descriptors from the pointdata.mdb file.
Flash memory and text strings in the VLC
With ROC 4.10b4 and later, a portion of the VLC’s flash memory is set aside to
accommodate up to 192 text strings for object descriptions and object names.
These 192 text strings are initially empty and are used on a first-come-firstserved basis. Text strings can be used for either object names or object
descriptions.
Each string can accommodate up to 30 characters. Valid characters include
letters, numbers, spaces, dashes, and parentheses.
Determining available flash memory (AI-109) The read-only point AI-109
indicates how many of the 192 memory locations are currently in use. The range
is 0-192.
For example, if the value of AI-109 is 189, there is room for only three
additional text strings for object names or descriptions (192 - 189 = 3).
Conversely, if the AI-109 value is 50, there is room for 142 additional text
strings for object names and descriptions (192 - 50 = 142).
Note Because there are more object names and object descriptions than there
are available text strings, choose carefully those points for which you want to
customize names and descriptions.
Object names
When you edit a point’s object name on the device, you use one of 192 available
text strings. When you delete the edited version, the object name reverts to the
default object name and the text string becomes available for another object
name or object description.
Microset points Microset points that are not assigned object names in flash
memory use the fixed Microsoft object names as described in Table 65 on
page 208. For example, Setpoint (SP) appears for AV-90. If a new object name is
written to an object that is different from the fixed Microset object name, the
new object name is stored in flash memory and is used as the object name.
Writing an empty object name or an object name that is identical to the fixed
Microset object name erases any object name from flash memory. When this
occurs, the Microset object name reverts to the fixed Microset object name and
the text string becomes available.
Example A Microset is connected to IN-0, and the default object name is AI 00.
If you edit the object name on the device to Space Temp, the edited object name
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is stored in flash memory and used as the object name for AI 00. If you later
delete the edited object name, the object name reverts to its default, AI 00, and
the text string that previously stored Space Temp becomes available.
Object descriptions
Object descriptions behave according to the setting of the Writable/DDC
Descriptions on the General tab of Device Settings. (See Figure 10 on page 38.)
Recommended setting Alerton recommends the DDC setting for devices
loaded with ROC files 4.10b4 or later. This allows VLCs to inherit the
descriptions that are assigned in the DDC file while still allowing you to
overwrite the descriptions from Envision for BACtalk if necessary.
Writable/DDC Descriptions set to DDC When Writable/DDC Descriptions is
set to DDC, flash memory is used only when the object description on the device
is different from the object description in the DDC.
The object description as defined in the DDC is its default. If both locations are
empty, the description is blank.
When you edit an object description on the device, one of the 192 text strings in
flash memory is used. Later, if you delete an edited object description—or if you
change a description back to its default value—the text string in flash memory
becomes available.
Example If the VLC DDC description for AI-0 is Space Temp, Space Temp is
the default description. If you change the description on from an Envision for
BACtalk screen to Training Classroom Temp, one of the 192 available text
strings is used. The description Space Temp continues to reside in the VLC DDC.
If you later delete the description Training Classroom Temp, the description
reverts to the default Space Temp, and the flash memory text string becomes
available.
The relationship between a device’s point data file and the point descriptions in
the device is critical. If the point data file is sent to the device and the point
descriptions in the data file do not match the object descriptions on the device,
the text strings in the flash memory are quickly consumed. You can avoid this
potential problem by using Device Manager to save point data file after you have
edited the descriptions in the VLC.
Writable/DDC Description set to Writable When Writable/DDC Descriptions
is set to Writable, flash memory is used whenever an object description is
defined on the device from Envision for BACtalk. The descriptions in the DDC
file are ignored.
This behavior can present problems because the available text strings can be
quickly used up with descriptions, leaving not enough text strings available for
object names.
Freeing up text strings
To make a text string available for reuse in flash memory, delete one or more
object descriptions or object ames on the device.
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 To free up a text string
1. Display the object name or object description property in an Envision
for BACtalk screen.
2. Do either of the following:
• Press BACKSPACE until all characters are erased.
• Highlight the characters and press DELETE.
3. When the field is empty, click OK to send the value to the device.
Upgrading Gen4 ROC files
When upgrading to version 4.10b4, perform a point data save before
downloading the new ROC file. This ensures that the object descriptions in the
device are preserved.
After downloading the new ROC file, send point data to the device. This places
up to 192 of the previous descriptions back into the VLC. Check the User
Request Monitor for any errors in sending point data.
Note A common error is a text string that is too long. Flash memory text
strings have a limit of 30 characters; in ROC versions earlier than 4.10b4, the
maximum limit is 38 characters.
For more information about upgrading ROC files, see any of the following
sources:
• For using the Auto Download option for ROC files, see the section
entitled “Automatically downloading a ROC file to controllers” in
Envision for BACtalk Operator’s Manual (LTBT-OP-EBT30).
• For step-by-step instructions for downloading ROC files, see Gen4 VLC
Installation and Operations Guide (LTBT-TM-GEN4VLC) or
VLCA-1688 Installation and Operations Guide
(LTBT-VLCA1688IOG).
Reverting to earlier versions of Gen4 ROC files
If you need to revert to a ROC version earlier than 4.10b4, save point data before
downloading the legacy ROC file. After the legacy ROC file is loaded, send
point data to restore the point descriptions. This is required because ROC files
earlier than 4.10b4 use a strict allocation of flash memory for description strings.
If you revert to an earlier ROC file after running 4.10b4 with the description and
object name capability and don't save point data, some or all of the descriptions
will appear garbled.
I MP O R TA N T When downgrading to an earlier ROC file, customized object
names revert to the legacy constructed, or fixed, object names. All non-Microset
related descriptions are restored.
When upgrading after previously reverting to an earlier version If you have
a VLC that has been upgraded to the new 4.10b4 ROC file wherein you
implemented this new description and object name functionality, then reverted to
an older ROC file, and later want to upgrade back to the new ROC file to
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implement the new naming functionality, you must write a valid description
string to AV-0 while running the old ROC file. Doing so ensures that the new
scheme properly clears the flash memory locations allocated for descriptions and
object names.
Updating existing applications
To best utilize the features of VLC ROC 4.10b4, define all of the point
descriptions in the VLC DDC application file, set the Writable/DDC
Descriptions parameter to DDC, and then update the device point data file so that
point data descriptions match DDC file descriptions.
Following are instructions on how to update your application using an
Alerton\Standard DDC application as an example.
Note For the following process to work. the DDC application drawing must
use the I/O tabs with defined descriptions.
 To define point descriptions
1. Open DDC drawing file.
2. If your drawing has I/O tabs that have a description but no point
defined, make certain that nothing is selected on the drawing, and then
propagate parameters:
• Visio 2007: From the VisualLogic menu, select Tools > Propagate
Parameters (or use the keyboard shortcut SHIFT + ALT + P).
• Visio 2010: From the VisualLogic ribbon, select Propagate (or use
the keyboard shortcut ALT + V + P).
3. If your drawing has I/O tabs with a description and point defined, open
the Device Settings and select the Point Setup tab.
4. Under Collect Points, select Collect new points from DDC and add
to Point Setup list and then click Apply at the bottom of the Device
Settings window.
5. On the Device Settings General tab, under Import/Export from/to
Excel table, click Export.
A new Excel file opens.
6. Review point list and edit descriptions as necessary.
Some points may not have descriptions or the description may not be
the one desired.
7. If the Microset/Microtouch points (AV-90 through AV-107 and BV-64
through BV-84) are not already defined in Point Setup, add them.
8. On the Device Settings General tab, under Import/Export from/to
Excel table, click Import.
9. Click Apply at the bottom of the Device Settings window.
If a point has two different descriptions in the drawing, the first one
collected appears in the list and exported file.
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10. Optional: To have the point have the same description throughout the
drawing, under Collect Points select Copy Point Setup descriptions
to I/O tab descriptions.
 To set the Writable/DDC option
On the General tab of Device Settings, set the Writable/DDC
Descriptions option to DDC, and then click Apply.
 To synchronize DDC file descriptions with device point data (.mdb) file
1. Save the drawing:
• Visio2007: From the VisualLogic menu select File > Save as
Drawing (or use the keyboard shortcut CTRL + ALT + S).
• Visio 2010: From the VisualLogic ribbon select Save as Drawing
(or use the keyboard shortcut ALT + V + S + A).
2. Save the DDC:
• Visio 2007: From the VisualLogic menu select File > Save Drawing
as DDC (or use the keyboard shortcut CTRL + ALT + E).
• Visio 2010: From the VisualLogic ribbon select Save as DDC (or
use the keyboard shortcut ALT + V + D +C).
3. Use Device Manager to send the DDC to devices.
4. When the DDC download is complete, save point data from devices to
update devices' point data file.
Writing VLC-444 object names and descriptions
VLC-444 object names and descriptions can be written from data displays if the
device has ROC file version 5.10 b9 or later. A ROC file upgrade may be
required to enable this feature.
Note The values of the object name and description are written to the same
memory location on the device. If you change one of them, the other will display
the new value.
Upgrading ROC files
Upgrading the VLC-444 ROC file is the same as upgrading the ROC in any
other device and can be done by copying the new ROC into the BACtalk System
folder and sending it using Envision for BACtalk Device Manager. For more
information see the Gen 4 VLC Installation and Operation Guide (LTBT-TMGEN4VLC) available on the Alerton Support Network.
Setting DDC to make points writable
 To make points writable
1. In VisualLogic, open the DDC file for the device.
2. Double click the controller icon on page 1.
3. Select the General tab.
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4. Select Writable from the Writable/DDC drop-down list.
5. Click Apply.
6. Send the file to the device using Envision for BACtalk Device Manager.
Writing object names and descriptions from displays
 To define an object name or description from a graphic display
1. Add the point to a data display as a prompted property.
2. Click the edit button.
The Edit Property dialog box appears.
3. Type a new name or description. Limit the length to 30 characters or
less.
4. Click OK.
N o t e You cannot save user-defined object names and descriptions
from a display to a DDC file. To change object names and descriptions
in a DDC file, edit the DDC file using a DDC editor or VisualLogic.
Where VLC-444 object name values come from
When Envision for BACtalk displays an object name, it gets the value from one
of four sources. It checks for these conditions in this order:
1. User-assigned value (DDC file must be set to use “Writable”
descriptors)
2. DDC-assigned value (DDC file must be set to use “DDC” descriptors)
3. Pre-defined value (hard coded value such as those used for Microset
points)
4. Value generated by the VLC-444 that typically mirrors the objectidentifier.
Where VLC-444 descriptions come from
When Envision for BACtalk displays a description, it gets the value from one of
four sources.
1. User-assigned value (DDC file must be set to use “Writable”
descriptors)
2. DDC-assigned value (DDC file must be set to use “DDC” descriptors)
3. Pre-defined value (hard coded value such as those used for Microset
points)
4. Blank value
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6
This section contains references for DDC functions available in global or building
controller DDC and VLC DDC. Some operational differences exist between
functions in a global or expandable controller and functions in a VLC. Mostly,
these relate to timing issues. Furthermore, some devices may exist only in global or
building controller or VLC DDC. These are indicated.
CAUTION In VisualLogic, it is possible to program global or building controller
DDC or VLC DDC with functions that cannot be executed in the device. Make
sure that you program only appropriate functions for the global controller or VLC
as appropriate.
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Function 1: End of Normal Sequence
Description Denotes the end of normal DDC and, if applicable, the beginning
of subroutine DDC space.
Remarks Function 1 must be included in every VLC or global controller DDC
program. Only one Function 1 can be programmed per VLC or global controller
DDC program.
END OF
NORMAL
Figure 38
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Function 2: End of Subroutine (global controller only)
Description Denotes the end of subroutine DDC.
Remarks Function 2 must be included if subroutine DDC is used.
100
END OF
SUBROUTINE
Figure 39
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Function 3: Set Context (global controller only)
Description Defines the set context device and is a critical component of
reusable subroutine DDC (see the example), providing a device instance context
for each iteration of the subroutine. The input may be either a data value equal to
a device instance, or a data point ID that identifies a particular BACnet device.
The set context device remains set until another Set Context Function executes.
Remarks When you enter a data point in global or building controller DDC,
you have three options: you can specify the device where the data point
originates, you can specify the local device (the global controller in which the
DDC executes), or you can choose a set context device. If you choose the set
context device, the function references the data point in the device instance of
the last Set Context Function to execute.
Example A subroutine transfers data to and from multiple VAV-SD
controllers. For each VAV-SD, a Function 67: Subroutine Caller calls the same
subroutine DDC. Substitution Point 0 in each Subroutine Caller is the device
instance of the associated VAV-SD. The first function in the subroutine is
Function 3: Set Context, with Substitution Point 0 entered as the context device
instance. All subsequent data points in the subroutine DDC that must reference
the associated VAV-SD are entered with the Set Context Device check box
selected.
Device
Instance
SET
CONTEXT
100
Figure 40
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Function 6: Velocity Pressure to fpm Converter
Description Performs square root extraction to convert an analog input that
represents velocity pressure (vp) to an analog signal that represents velocity in
feet per minute (fpm).
Remarks The inputs are input, zero, and k factor. Input should be a signal
representing the velocity pressure (vp) of the measured airflow. The Input must
be a positive number. The k factor is used as a multiplier. The zero is used to
compensate for variations in transducer readings at zero airflow; set the zero
input equal to the value of the vp input when there is no airflow. The output of
Function 6 can be expressed as:
Output = k vp – z
where
k = k factor
vp = velocity pressure input
z = zero
The k factor can be used to correct for the pickup multiplier and any other factors
necessary to convert the input signal value to actual velocity pressure. Most vp
pickups (except true pitot tubes) produce a pressure differential that is greater
than the actual vp. The conversion factor is typically referred to as a pickup
multiplier. Use the following equation to calculate the k factor using the pickup
multiplier (PM).
Note This assumes the input has been scaled to equal the sensed pressure in
inches of water column.
1kfactor = 4005 -------PM
Input
Zero
K factor
ZERO
OUT
K
Output
100
Figure 41
Velocity pressure
Note To use this function to calculate the square root of a variable, enter Data 0
in (zero), Data 1 in (K factor), and assign your variable as the input. The output
is the square root of your input variable.
Note The input cannot be negated or reversed.
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Function 8: Enthalpy Calculator
Description Calculates enthalpy from temperature and relative humidity.
Remarks Function 8 uses two input values—temperature in degrees F and
relative humidity (RH) in %—to calculate enthalpy in BTU/lb. Minimum
temperature used is 0 degrees F. Maximum temperature used is 102 degrees F.
Inputs must be positive numbers.
Maximum enthalpy that can be calculated is 68 BTU/lb. at 102 degrees
Fahrenheit and 100% relative humidity. The accuracy of this calculation is best
between 55 and 80 degrees Fahrenheit.
Temp.
%RH
Figure 42
°F
%RH
Output
100
Enthalpy calculator
Note Controllers that support BD6 have an enhanced Enthalpy Calculator for
both BD4 and BD6. The enhanced Enthalpy Calculator is based on equations
from the 1993 ASHRAE Fundamentals Handbook. The enthalpy calculation is
based on an atmospheric pressure of 14.696 psia and dry-bulb temperature is
limited to -148 to 392 degrees F.
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Function 9: Wet Bulb Calculator (Advanced VLC only)
Description Calculates wet bulb temperature from dry temperature, relative
humidity, and altitude.
Remarks Function 9 uses three input values—dry bulb temperature in degrees
F, relative humidity (RH) in % in the range 0-100, and altitude in feet above sea
level—to calculate wet bulb temperature in degrees F. Minimum temperature
used is 32 degrees F. Maximum temperature used is 100 degrees F. Inputs must
be positive numbers. Values of % RH that are less than zero or greater than 100
are converted to 0 and 100, respectively. Wet bulb temperature is calculated once
every 10 seconds.
Figure 43
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Function 10: Two-Input AND Gate
Description Performs the logic AND function of two binary-type inputs and
sets a binary output accordingly.
Remarks The output is set to ON only if both inputs are ON. If either input is
OFF, the output is OFF.
In global or building controller DDC NULL values are considered OFF.
Input 1
Output
Input 2
100
Figure 44
Function 10: Two-Input AND gate
Ta ble 25
118
Function output logic
Input 1
Input 2
Output
OFF
OFF
OFF
ON
OFF
OFF
OFF
ON
OFF
ON
ON
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Function 11: Six-Input AND Gate
Description Performs the logical AND function of six binary inputs and sets
the binary output accordingly.
Remarks Function 11 is similar to Function 10: Two-Input AND Gate, except
that six binary inputs are logically compared to generate one binary output.
Function 11 is used when there are more than two inputs. All six inputs must be
assigned. If there are fewer than six inputs, the unused inputs should be set to
any of the used input values or to a data value of (TRUE) but cannot be left
blank.
The function uses all six inputs to set the output ON or OFF. If any of the six
inputs is OFF, the output is set to OFF. The output is set to ON only if all of the
six inputs are ON.
In global or building controller DDC NULL values are considered OFF.
Input 1
Input 2
Input 3
Output
Input 4
100
Input 5
Input 6
Figure 45
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Function 12: Two-Input OR Gate
Description Performs the logical OR comparison of two binary inputs and sets
the binary output accordingly.
Remarks The output is ON if either or both inputs is ON. The output is OFF
only if both inputs are OFF.
In global or building controller DDC NULL values are considered OFF.
Input 1
Output
Input 2
100
Figure 46
Function 12: Two-Input OR gate
Ta ble 26
120
Function output logic
Input 1
Input 2
Output
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
ON
ON
ON
ON
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Function 13: Six-Input OR Gate
Description Performs the logical OR of six binary inputs and sets the binary
output accordingly.
Remarks Function 13 is similar to Function 12: Two-Input OR Gate, except
that it works with six binary inputs to generate one binary output. Function 13 is
used when there are more than two inputs. All six inputs must be assigned. If
there are fewer than six inputs, the unused inputs should be set to any of the used
input values or to a data value of (False) but cannot be left blank.
The function uses all six inputs to set the output as ON or OFF. If any of the six
inputs is ON, the output is ON. The output is OFF only if all six inputs are OFF.
In global or building controller DDC NULL values are considered OFF.
Input 1
Input 2
Input 3
Output
Input 4
100
Input 5
Input 6
Figure 47
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Function 15: One Shot
Description Sets the output ON for one pass of DDC whenever the input
transitions from OFF to ON.
Remarks The output remains ON only for a single pass of DDC, even if the
input stays ON for a longer or period.
Input
Output
100
Figure 48
Function 15: One Shot
Example Figure 49 shows how to do a lead/lag sequence using F 15: OneShot
and F 18: Two-Input Exclusive OR.
Figure 49
122
Toggling a BV for selection of lead/lag
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Function 16: Delay on Make (seconds)
Description Delays a binary transition from OFF to ON.
Remarks When the input transitions from OFF to ON, the function or output
transitions ON only after the specified delay time (t). If the input value
transitions OFF at any time during the delay period, the timer is reset. The delay
time (t) resolution is one tenth of a second. The output transitions OFF
immediately when the input transitions OFF.
In global controller DDC, changes to the delay time have no affect on the
operation of the function when the input is ON. In VLC DDC, changes to the
delay time affect output status unless the output is already ON.
Note The time delay function contains logic to adjust for DDC cycles that take
longer than 0.1 second to complete, therefore keeping accurate time regardless
of the DDC cycle time. The stored delay timer associated with each time delay
function is limited by timing range. For delays less than 1638.3 seconds (27.3
minutes), resolution is in 0.1 second increments. For delays between 1638.3 and
16383 seconds (0.45 hour to 4.5 hours) resolution is in 1 second increments. For
delays between 16383 seconds and 163830 seconds (4.5 hours to 45.5 hours)
resolution is in 10 second increments. The delay is limited internally to a
maximum of 45.5 hours.
Delay
Input
sec
DOM
Output
100
Figure 50
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Function 17: Delay on Break
Description Delays a transition from ON to OFF.
Remarks When the input changes from ON to OFF, the output changes to OFF
after a delay time (t). If the input value changes to ON at any time during delay
time (t), the timer is reset. The output transitions ON immediately when the input
transitions ON.
In global controller DDC, changes to the delay time have no affect on the
operation of the function when the input is OFF. In VLC DDC, changes to the
delay time affect output status unless the output is already OFF.
Note The time delay function contains logic to adjust for DDC cycles that take
longer than 0.1 second to complete, therefore keeping accurate time regardless
of the DDC cycle time. The stored delay timer associated with each time delay
function is limited by timing range. For delays less than 1638.3 seconds (27.3
minutes), resolution is in 0.1 second increments. For delays between 1638.3 and
16383 seconds (0.45 hour to 4.5 hours) resolution is in 1 second increments. For
delays between 16383 seconds and 163830 seconds (4.5 hours to 45.5 hours)
resolution is in 10 second increments. The delay is limited internally to a
maximum of 45.5 hours.
sec
Delay
Input
DOB
Output
100
Figure 51
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Function 17: Delay on Break
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Function 18: Two-Input Exclusive OR
Description Sets the binary output OFF if both inputs match (both ON or both
OFF), and sets the output ON if only one of the inputs is ON.
Remarks Function 18 is similar to Function 12: Two-Input OR Gate, with one
exception: the output is OFF if both inputs are ON. Other values remain
consistent with the OR function: the output is OFF if both inputs are OFF, and
the output is ON only if one input is ON.
In global or building controller DDC NULL values are considered OFF.
Input 1
Output
Input 2
100
Figure 52
Ta ble 27
Function 18: Two-Input Exclusive OR
Function output logic
Input 1
Input 2
Output
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
ON
ON
ON
OFF
As an example, the figure below shows a non-Alerton device communication
failure at the global controller (a BCM or VLX).
• XOR is located in any BCM or VLX.
• Any valid binary point works.
• BI and or BV can be from any BACnet device.
Figure 53
Function 18: Two-Input Exclusive OR
See Figure 49 on page 122 for an example of how to do a lead/lag sequence
using F 15: OneShot and F 18: Two-Input Exclusive OR.
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Function 20: Flip Flop Gate
Description Two binary inputs, set (S) and reset (R), are used to switch the
binary output between ON and OFF, respectively.
Remarks Function 20 has two binary inputs, set (S) and reset (R), which
determine how the output is set. A momentary ON of the set (S) input turns the
output ON if the reset (R) input is OFF. The output stays ON once it is set, even
if the set (S) input transitions OFF. If the reset (R) input turns ON, the output
transitions OFF. The reset (R) input has priority over the set (S) input, so the
output is OFF if both inputs are ON.
Output
Set
Reset
100
Figure 54
Function 20: Flip Flop Gate
Ta ble 28
126
Logic table
Set input
Reset input
Output
Momentarily ON
OFF
ON - Stays ON
OFF
Momentarily ON
OFF - Stays OFF
ON
ON
OFF
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Chapter 6 | DDC function reference
Function 21: Anti Short Cycle Relay
Description Prevents an output from changing state repeatedly, or “short
cycling,” by setting minimum ON and OFF times.
Remarks When the output turns ON, it stays ON for the minimum ON time,
even if the input goes OFF.
When the output goes OFF, it stays OFF for the minimum OFF time, even if the
input goes ON.
Minimum ON and OFF times can be set to different values.
For VLCs, the time resolution is 0.1 second. For global controllers, the time
resolution is 1 second and must be entered in whole seconds; the decimal value
is ignored. For example, 308.7 = 308.
M inim um O n
Inp ut
O utp ut
M inim um O ff
Figure 55
© Honeywell
100
Function 21: Anti Short Cycle Relay
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Function 22: Analog Comparator
Description Compares two analog inputs and produces a binary signal as a
result of the comparison. Inputs must be positive numbers.
Remarks The output is ON when the plus input is greater than or equal to the
minus input plus the trigger deadband (TDB). The output goes OFF when the
plus input is less than or equal to the minus input, minus the restore deadband
(RDB).
Figure 56
Function 22: Analog Comparator
Ta ble 29
Function 22 logic
Condition
Output
Plus Input > (Minus Input + TDB)
ON
Plus Input < (Minus Input - RDB)
OFF
(Minus Input - RDB) < Plus Input < (Minus Input + TDB)
No change
Note See page 21 for an example.
Note For direct acting control assign the Process Feedback to the Plus Input,
and the Process Setpoint to the Minus Input.
Note For reverse acting control assign the Process Feedback to the Minus Input
and the Process Setpoint to the Plus Input.
Note The inputs cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 23: Change of State (COS) Detector
Description Turns a binary output ON momentarily whenever the analog input
changes by more than the value entered for deadband (DB). Inputs must be
positive numbers.
Remarks Function 23 compares the input value to a stored value. The stored
value is set to the input value each time the output is ON and does not change
while the output is OFF.
The output is ON when the input is greater than the stored value plus the DB, or
the input is less than the stored value minus the DB. Otherwise, the output is
OFF.
Example If DB is set to 1.0, and the input when the DDC is first initiated is
13.2 (which then becomes the stored value), then the output turns ON for one
pass of the DDC the first time the input reaches 14.3 or greater or 12.1 or less. If
the input varies between 12.2 and 14.2, the stored value remains the same.
If the input were to suddenly change to 14.6, for example, the output would turn
ON and 14.6 would become the new stored value.
Deadband
Input
Output
100
Figure 57
Function 23: Change of State (COS) Detector
Note The input cannot be negated or reversed.
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Function 24: Restrictor
Description Restricts the rate of change of an analog value.
Remarks The inputs to Function 24 are made up of an analog data input (IN),
binary reset input (RST), maximum up count (MUP), and maximum down count
(MDN). Inputs must be positive numbers. As long as the binary reset input is
ON, the output attempts to match the analog data input; however, the rate of
change of the output is limited by the maximum up and maximum down inputs.
The maximum up input regulates the maximum increase allowed in the output
per second, while the maximum down input regulates the maximum decrease
allowed in the output per second. The maximum up count and maximum down
count are independently adjustable.
The output is set immediately to zero when the reset input turns OFF.
Input
Output
Reset
Maximum Up
100
Maximum Down
Figure 58
Function 24: Restrictor
Note This device is processed every tenth of a second (.10) second in VLC
DDC. Therefore, the Maximum up and Maximum Down values are divided by
10 and applied for each pass of DDC.
Example Regulate the actuator position indication (AV) on the data display to
match the actual speed of the actuator.
Figure 59
Example of using Function 24: Restrictor
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 26: Priority Array Read (VLC only)
Description Outputs the value of a specified element of an object's BACnet
priority-array index and indicates with a separate output whether the specified
element is NULL.
Remarks The BACnet object (OBJ) and priority-array index (PR) are inputs to
this function. The data output equals the current value of the specified element of
the priority array, except when the element is NULL, in which case the data
output is 0 (or OFF when used as a binary value).
The function's NULL output is binary. It is OFF if the specified element is
NULL and ON if other than NULL.
Object
OBJ
Priority
PR
Data
Output
Null
Output
100
Figure 60
BO/BV
Function 26: Priority Array Read (VLC)
OBJ
DATA
PR
NULL
Output = ON only when BO/B
Priority is ON
NULL = OFF
NOT NULL = ON
Figure 61
BO/BV
Function 26: Example for determining when a priority is ON
OBJ
DATA
PR
NULL
DATA
NULL
0
(ON) NOT NULL
1
(OFF) NOT NULL 0
Figure 62
© Honeywell
Output = ON only when BO/BV
Priority is OFF
NULL
0
1
1
XOR OUT
0
0
1
Function 26: Example for determining when a priority is OFF
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Function 27: Increment/Decrement
Description Increase the In/Out value by an Up/Pass value or decrease it by a
Down/Pass value only if an ON value is passed to the Up Input or Down Input,
respectively, for each pass of the DDC.
Remarks For each pass of the DDC, the value of the Up/Pass input value is
added to In/Out whenever the Up Input is ON.
Similarly, the value of the Down/Pass input is subtracted from the In/Out
whenever the Down Input is ON. The In/Out value is limited to the range defined
by the Upper Limit and Lower Limit inputs.
Note that this function only adds to In/Out point or subtracts from it when either
the UP input or the Down Input is ON.
Upper Limit
+ Amount
+ In
Output
- In
- Amount
100
Lower Limit
Figure 63
Function 27: Increment/Decrement
Note The inputs cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 28: Gated Transfer
Description Write the input value to the output value only when the Gate input
is ON.
Remarks This function does not write to the output if the Gate input is OFF.
Note that, unlike Function 47: Sample and Hold, this function does not store the
value of the output, meaning the output does not necessarily remain constant
when the Gate input is OFF. Inputs must be positive numbers.
Gate
Input
Output
100
Figure 64
Function 28: Gated Transfer
Note The input cannot be negated or reversed.
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Function 29: Gated Priority Transfer (VLC only)
Description Write the input value to a BACnet object with the specified
priority other than the default priority. When the binary gate control is OFF, a
NULL value is written to the specified output.
Remarks When the binary gate control is ON, the value of the input is written
to the output (which should be a BACnet object), with the priority specified by
the priority input. The output must be a BACnet object that has a priority array.
Inputs must be positive numbers.
OBJ
Input
PR
Object
Priority
100
Gate
Figure 65
Function 29: Gated Priority Transfer (Priority Write)
Note Function 29 cannot write to the following priority indices:
•
1: Manual Life Safety.
•
2: Automatic Life Safety.
•
5: Critical Equipment.
•
6: Minimum ON/OFF.
•
8: Manual Operator.
•
9: Alerton Global Controller.
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 30: Subtraction
Description Subtracts one input value from another.
Remarks Function 30 subtracts the value of analog input 2 (-) from the value of
analog input 1 (+). The output is then set to the result.
Input 1
Output
Input 2
100
Figure 66
© Honeywell
Function 30: Subtraction
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Function 31: Addition
Description Adds two input values.
Remarks Function 31 adds analog input 1 and analog input 2. The output is
then set to the result.
Input 1
Output
Input 2
100
Figure 67
136
Function 31: Addition
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Chapter 6 | DDC function reference
Function 32: Transfer Data
Description Copies a value from one property to another.
Remarks Function 32 is used to transfer analog or binary data from one
property to another without changing the data content. Inputs must be positive
numbers.
Input
Output
100
Figure 68
Function 32: Transfer Data
Note The input cannot be negated or reversed.
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Function 35: Multiplication
Description Multiplies (*) one value by another.
Remarks Input (multiplicand) is multiplied by multiplier, and the product is
written to the output.
Input
Output
100
Multiplier
Figure 69
138
Function 35: Multiplication
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 6 | DDC function reference
Function 36: Division
Description Divides one value by another.
Remarks Input (dividend) is divided by divisor, and the resulting quotient is
written to the output.
Input
Output
100
Divisor
Figure 70
© Honeywell
Function 36: Division
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Function 39: Within a Range
Description Turns the output from OFF to ON whenever the input value is
within the range defined by the High Limit (Limit 1) and Low Limit (Limit 2)
values.
Remarks Function 39 has three analog inputs and one binary output. Inputs
must be positive numbers. Although the limits are labeled High Limit and Low
Limit, The High Limit does not have to be greater than the Low Limit. The
output is ON whenever the input value is greater than or equal to the Low Limit
value and the input value is less than or equal to the High Limit value.
Otherwise, the output is OFF.
Note that the output is ON if the input value is equal to either of the limits, and
one does not necessarily have to be less than the other.
High Limit
HI
Input
IN
Output
Low Limit
LO
100
Figure 71
Function 39: Within a Range
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 40: Switch
Description Selects an output value from two input values, depending on the
value of a binary input.
Remarks Function 40 has two analog inputs, one binary input, and an analog
output. The output equals the ON analog input if the binary control input is ON,
and the output equals the OFF analog input if the binary control input is OFF.
Inputs must be positive numbers.
Control
ON
Output
OFF
100
Figure 72
Function 40: Switch
Note The ON and OFF inputs cannot be negated or reversed.
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Function 41: High/Low Limiter
Description Restricts an analog value to a range defined by two limits.
Remarks Function 41 has three analog inputs and one analog output. The
output equals the analog input as long as it is within the range defined by the
high limit and low limit. Inputs must be positive numbers.
If the analog input exceeds the high limit, the output is set to the value of the
high limit. If the analog input is less than the low limit, the output is set to the
low limit.
If the high limit value is less than the low limit value, the high limit has priority
(that is, the output is set to the high limit, regardless of the analog input value).
High Limit
Input
HI
Output
IN
Low Limit
LO
100
Figure 73
Function 41: High/Low Limiter
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 44: Run-time Accumulator
Description Outputs a cumulative analog run time value for a binary input.
Remarks The output (run time) equals the total accumulated time, in hours,
that the binary input has been ON. Run time increases by 1 for each hour that the
input has been ON. The AV is written to only when an additional hour of run
time has accumulated.
Note This is the only VLC DDC function that can write to an EEPROM-stored
AV in C3-series VLCs.
Input
Output
100
Figure 74
© Honeywell
Function 44: Run-time Accumulator
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Function 45: Two-Point Linear Converter
Description Performs a linear conversion on the input to produce an output.
Two points (IN1, OUT1) and (IN2, OUT2) are used to define the line that
converts input to output.
Remarks A straight line relationship determines the output as a function of the
input.
The output equals the value of OUT1 when the input equals the value of IN1.
Likewise, the output equals the value of OUT2 when the input equals the value
of IN2. The output is not limited to the defined points.
Input
OUT 2
Output
OUT 1
IN 1
100
IN 2
Figure 75
Function 45: Two-Point Linear Converter
Example 1 When used to calculate a heating water setpoint, the output
calculates beyond the limits defined and possibly creates an unwanted condition.
To limit the output, place Function 41: High/Low Limiter on the output.
Figure 76 shows that the AV-1 is limited to a range of 180°F to 110°F.
Figure 76
144
Function 45 example: Limiting range to 180°F to 110°F
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 6 | DDC function reference
Example 2 To rescale an analog output for a 4-20mA actuator, Alerton
controllers with analog outputs generate a 0~20mA signal. To properly control a
4~20mA device, rescale the output so that at 0% the signal is 4mA and at 100%
the signal is 20mA.
Figure 77 shows how to use Function 51: Proportional Integral (PI) Controller to
rescale the output of Function 45:Two-Point Linear Converter so that 0~100%
results in a 4~20mA signal.
Function 51:
Proportional Integral
Controller
Function 45: Two-Point
Linear Converter
Figure 77
Function 51 and 45 example of use
Note VisualLogic refers to inputs differently from DDC editors. When using a
DDC editor, use the following to translate: X1 = IN 1, X2 = IN 2, Y1 = OUT 1,
Y2 = OUT 2.
Note Inputs must be positive numbers. They cannot be negated or reversed.
© Honeywell
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Function 46: Linear Converter
Description Performs a linear conversion on the input and produce an output
using zero and range values as follows: Output = Zero + (Input x Slope). Inputs
must be positive numbers.
Y = MX + B
Where;
• Y is the scaled output (OUTPUT).
• M is the slope of the line or range of the scale (S).
• X is the input to be scaled (INPUT).
• B is the zero value (Z).
When the input is zero the output equals the zero (Z) value.
Slope
Zero
S
Z
100
Input
Figure 78
Output
Function 46: Linear Converter
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 47: Sample and Hold
Description Records and stores an analog value as prompted by a binary input.
Remarks Function 47 has one analog input, one binary sample control (CTRL)
input, and an analog output. When the CTRL input is ON, the output and the
stored value are set equal to the input. When the CTRL input is OFF, the output
is set to the last stored value. The inputs must be positive numbers.
Control
Input
Output
100
Figure 79
Function 47: Sample and Hold
Note The input cannot be negated or reversed.
4.8s
Delay
Input
Input of
Delay O n M ake
is Negated
DO M
O utput
Control
Input
Figure 80
© Honeywell
O utput
Function 47 example: sampling an input variable every five seconds
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Function 48: Analog to Timed Binary Converter
Description Cycles the output ON for a portion of each cycle time (CYC),
which is adjustable, based on a 0.0 to 100.0 analog input control signal. A
minimum ON time (MON) and minimum OFF time (MOF) prevent short
cycling.
Remarks The output turns ON only if the calculated ON time is greater than the
MON. If the output is ON, it remains ON until it has been ON for the calculated
ON time and the MON has expired. The output remains ON continuously if the
calculated OFF time is less than the MOF.
Inputs must be positive numbers.
Time resolution is 1 second for VLC DDC and global or building controller
DDC.
Note One second is spent transitioning from ON to OFF. You may want to
compensate for this by reducing the cycle time by one second.
Input
CalculatedOnTime = CycleTime  --------------
100.0
CalculatedOffTime = CycleTime – CalculatedOnTime
Input
IN
Cycle
CYC
Min. ON
MON
Min. OFF
MOF
Output
100
Figure 81 Function 48: Analog to Timed Binary Converter (analog to binary
output time)
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 49: Thermal Valve, Modulating Output (VLC only)
Description Pulses the binary output ON every 2.55 seconds, varying the ON
time of the output (pulse width) from 0 to 2.55 seconds as the analog input varies
from 0–100.0. If analog input is 0, the output remains OFF.
Remarks The pulse width is calculated using a nonlinear conversion to better
match the thermal modulating valve (TMV). Do not use a NOT on the output of
this device. To reverse a valve, reverse the signal by subtracting it from 100
before inputting it to this function.
Figure 82
Function 49: Thermal Valve, Modulating Output (VLC only)
Note The input cannot be negated or reversed.
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Function 50: High/Low Selector
Description Selects the highest and lowest values from among six inputs.
Remarks Function 50 has six analog inputs and two analog outputs. The high
output equals the value of the highest input. The low output equals the value of
the lowest input. All inputs must be assigned. Inputs must be positive numbers.
If fewer than six inputs are needed, repeat one or more of the input assignments
to fill the remaining inputs.
Input 1
Input 2
High
Output
HI
Input 3
Input 4
Input 5
Low
Output
LO
Input 6
Figure 83
100
Function 50: High/Low Selector
Note The input cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 51: Proportional Integral (PI) Controller
Description Provides proportional integral (PI) control. Output is adjusted in
an attempt to get the feedback input (FB) to match the setpoint (SP).
Remarks Inputs are FB (typically a space temperature), setpoint (SP),
proportional constant (Kp), integral constant (Ki), maximum integral change
(Imax), integral startup (STUP), and integral limit (Ilim). The output of this
function can be expressed as P+I+50, where P is the proportional component and
I is the integral component. Each of these is calculated as indicated below. Note
that Error (E) is an intermediate variable equal to FB - SP. Inputs must be
positive numbers.
Output = P + I + 50
where;
P = Kp(E)
I = Iprev + Iinc (I is limited to Ilim)
K
 60
Iinc= E  ------i , which is calculated once per second. (Iinc is limited to a maximum
Imax
of ------------- .)
60
Iprev is I from the most recent calculation. When DDC initializes, Iprev is set to
STUP for the first DDC loop.
Also, when Ki = 0, the value of I = STUP.
See “Understanding BACtalk PI and PID functions” on page 90 for more
information.
Proportional
Constant
Integral
Constant
Setpoint
Feedback
Max. Integral
Change
Integral
Limit
Integral
Startup
Figure 84
Kp
Ki
PI
SP
FB
I max
I lim
Output
100
STUP
Function 51: Proportional Integral (PI) Controller
Example Figure 77 on page 145 shows an example of Function 51: Proportional
Integral Controller used with Function 45: Two-Point Linear Converter.
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Function 52: Proportional Integral Derivative (PID) Controller
Description Provides proportional integral derivative (PID) control. Function
52 uses a PID algorithm to adjust the output in an attempt to get the input to
match the setpoint.
Remarks This function is similar to Function 51, except that a derivative
component (D) is included in the output calculation. D is the rate of change in E
per second times the constant Kd, which is an input to the device. Inputs must be
positive numbers.
Note that Error (E) is an intermediate variable equal to FB – SP.
Output = P + I + D + 50
where;
P and I are as calculated for Function 51.
D = Kd(E – Eprev). Eprev represents the value of E from the previous pass of
DDC. D is calculated every 1 second in VLCs, global controllers, and
expandable controllers.
Proportional
Constant
Integral
Constant
Derivative
Component
Feedback
Max. Integral
Change
Integral
Startup
Figure 85
152
PID
SP
FB
Setpoint
Integral
Limit
Kp
Ki
Kd
Output
I max
I lim
STUP
100
Function 52: Proportional Integral Derivative (PID) Controller
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 6 | DDC function reference
Function 54: Floating Motor Controller with No Time-out
Description Provides floating point control of a motor based on a 0–100.0
control signal.
Remarks Function 54 has three analog inputs, two binary outputs, and one
analog output. The input control signal (0.0–100.0) is compared to the current
motor position (as estimated internally by the function). If the desired position is
greater than the current position by more than deadband (DB), the open motor
(OP) output is ON. If the desired position is less than the current position by
more than DB, the close motor (CL) output is ON. If the current position is
within DB of the input, both binary outputs remain OFF.
The motor time (MT) input represents the time required (in seconds) for the
motor to go from fully closed to fully open. The function estimates the current
motor position (%) output based on the motor time and the cumulative ON times
of the open motor and close motor outputs.
As the motor modulates open and closed, the function-estimated motor position
typically deviates farther from the actual position. Also, the VLC assumes on
power up that the motor is fully closed and pulses the motor open to the
currently-desired position.
This means that the motor can also get out of phase with the function-estimated
position if it is driven open and a power interrupt occurs. Use the initialization
flag, which is ON only during the first DDC loop, and additional DDC to
eliminate this out-of-phase condition on power-up. When the control signal
reaches 0.0 or 100.0 and the motor is driven fully closed or open for twice the
duration of the Motor time, the estimated position is automatically recalibrated.
Inputs must be positive numbers. Use only an integer for motor time.
Figure 86
Function 54: Floating Motor Controller with No Time-Out
Note For most applications, using a deadband value of three is typically a good
choice. The deadband is internally limited to 50/motorspeed. Therefore, if the
user defines a deadband of 10% and the motorspeed is 60 seconds, the deadband
is limited to a minimum of 50/60 or 0.8333%. When the input signal becomes
greater than deadband, the output activates for a minimum of 0.5 seconds.
Note The input cannot be negated or reversed.
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Function 55: Floating Motor Controller with Time-out
Description Provides floating point control of a motor (or any device driven
open or closed by a BO) based on a 0–100.0 control signal.
Remarks This function is the same as Function 54, with the addition of a time-
out feature. When the input remains at 0.0 for an extended period, the close
command (CL) output turns OFF Motor time (MT) seconds after the estimated
damper position is fully closed. When the input remains at 100.0 for an extended
period, the open command (OP) output turns OFF MT seconds after the
estimated damper position is fully open.
Use an integer only for Motor time.
Figure 87
Floating Motor Controller with Time-Out
Note The input must be a positive number. It cannot be negated or reversed.
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Chapter 6 | DDC function reference
Function 60: Read External Device (VLC v4.02 or later)
Description Reads data from an external BACnet device object at a specified
rate (READ FREQUENCY = seconds).
Remarks The INPUT is the device instance, object, and property that is
transferred to the present-value of the OUTPUT object. If the VLC can
successfully read the INPUT, the DATA RELIABILITY is 1 (ON), otherwise it
is 0 (OFF). NULL OUTPUT is normally 0 (OFF). If the device object being read
contains a BACnet value of NULL (empty), the NULL OUTPUT is set to 1
(ON) to indicate the DATA OUTPUT is invalid.
Figure 88
Function 60: Read External Device (RED) (VLC v4.02 or later)
CAUTION Use the RED function to pull data rather than push it using the
WED function because troubleshooting can become complex where WED
functions are used. For example, if a VLC value changes with no apparent
explanation, and there are some WED functions used in some VLCs, the user
must examine the DDC in every VLC in the system to determine which one has
the WED function.
CAUTION When DDC is first started after being loaded or after a power cycle,
data values from RED and REDS functions are 0 (or OFF if a binary value).
They remain at 0 until a successful read is completed. In the event that the RED
or REDS function loses communication with the target device, the data value
remains at the last retrieved value. To prevent problems, use the data integrity
output of the RED and REDS functions in your DDC as appropriate.
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Function 61: Read External Slave Device (VLC v4.02 or later)
Description Reads data from an external BACnet slave device object at a
specified rate (READ FREQUENCY =seconds).
Remarks The NETWORK and MS/TP MAC specify the network and MAC
address of the external object. The INPUT is the device instance, object, and
property that is transferred to the present-value of the OUTPUT object. If the
VLC can successfully read the INPUT, the DATA RELIABILITY is 1 (ON),
otherwise it is 0 (OFF). NULL OUTPUT is normally 0 (OFF). If the device
object being read contains a BACnet value of NULL (empty), the NULL
OUTPUT is set to 1 (ON) to indicate the DATA OUTPUT is invalid. Otherwise,
NULL OUTPUT is set to 0 (OFF).
Figure 89
later)
Function 61: Read External Slave Device (REDS) (VLC v4.02 or
Note If the slave device that is being read is on the same MSTP network, set
the Network number to 0 (zero).
CAUTION When DDC is first started after being loaded or after a power cycle,
data values from RED and REDS functions are 0 (or OFF if a binary value).
They remain at 0 until a successful read is completed. In the event that the RED
or REDS function loses communication with the target device, the data value
remains at the last retrieved value. To prevent problems, use the data integrity
output of the RED and REDS functions in your DDC as appropriate.
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Function 62: Write External Device (VLC v4.02 or later)
Description Writes data (DATA TO WRITE) to an external BACnet device
object.
Remarks The DESTINATION specifies the object, property, and index to be
written to. A write is attempted whenever the DATA TO WRITE changes by the
amount of DEADBAND from the last written value. DATA/NULL is set to 0
(DATA) to send the value in DATA TO WRITE, and 1 (NULL) if the special
BACnet NULL (empty) value is to be written. The WRITE RELIABILITY is set
to 1 (ON) when the external device acknowledges the write. It is set to 0 (OFF)
whenever the external device does not respond.
Figure 90
Function 62: Write External Device (WED) (VLC v4.02 or later)
CAUTION Use the RED function to pull data rather than push it using the
WED function because troubleshooting can become complex where WED
functions are used. For example, if a VLC value changes with no apparent
explanation, and there are some WED functions used in some VLCs, the user
must examine the DDC in every VLC in the system to determine which one has
the WED function.
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Function 63: Write External Slave Device (VLC v4.02 or later)
Description Writes data (DATA TO WRITE) to an external BACnet slave
device object.
Remarks The NETWORK and MS/TP MAC specify the BACnet network and
MAC where the slave device resides. The DESTINATION specifies the object,
property, and index to be written to. A write is attempted whenever the DATA
TO WRITE changes by the amount of DEADBAND from the last written value.
DATA/NULL is set to 0 (DATA) to send the value in DATA TO WRITE, and 1
(NULL) if the special BACnet NULL (empty) value is to be written. The
WRITE RELIABILITY is set to 1 (ON) when the external device acknowledges
the write. It is set to 0 (OFF) whenever the external device does not respond.
Figure 91
158
Write External Slave Device (WEDS) (VLC v4.02 or later)
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Chapter 6 | DDC function reference
Function 67: Subroutine Caller (global controller only)
Description Calls a subroutine and sets values of the substitution points to be
used for the subroutine.
Remarks When Function 67: Subroutine Caller executes, the next function
executed is the sequence number specified as the Subroutine's Starting Sequence
in the Subroutine Caller setup. The Subroutine Starting Sequence must be
programmed at a sequence number higher than Function 1: End of Normal and
lower than Function 2: End of Subroutine (that is, it must be outside normal
DDC space and within subroutine DDC space). Functions execute in order until
End of Subroutine is encountered, at which point program execution returns to
the normal DDC space, beginning with the function immediately after the
Subroutine Caller.
Parameters are equivalent to substitution points. Parameter 0, for example, is
equivalent to Substitution Point 0. When subroutine DDC encounters an input or
output defined as a substitution point, the value or data point entered at the
Subroutine Caller is used.
Each Subroutine Caller can have different data points assigned. In this way, a
single DDC subroutine can execute using different data points and values, as
long as the subroutine is called with different Subroutine Callers.
TO:
5000
SUBROUTINE CALLER
Figure 92
NULL
NULL
NULL
NULL
NULL
NULL
NULL
100 NULL
Function 67: Subroutine Caller (global controller only)
Note You can configure the subcaller function to display or hide the
substitution points on the VisualLogic drawing.
Note Do not define a substitution point as another substitution point.
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Function 70: Polynomial (Advanced VLC only)
Description Algebraic function consisting of a sum of multiple terms, each
term consisting of a constant multiplier and a variable raised to an integral
power.
Remarks The output is the value of the polynomial A + Bx + Cx2 + Dx3 + Ex4.
Figure 93
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Chapter 6 | DDC function reference
Function 71: Power (Advanced VLC only)
Description Raises x to the y power.
Remarks The output is the mathematical result of input x raised to the power of
input y.
Figure 94
© Honeywell
Function 71: Power (Advanced LVLC only)
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Function 72: In - Natural logarithm (Advanced VLC only)
Description The natural logarithm of x (written loge(x) or ln(x)) is the power to
which e would have to be raised to equal x, where e is an irrational number that
is approximately 2.718281828.
Remarks The output is the value y where ey = x. The input x must be greater
than 0.
Figure 95
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Function 73: Log Base 10 (Advanced VLC only)
Description The logarithm base 10 of x (written log10(x)) is the power to
which 10 would have to be raised to equal x.
Remarks The output is the value y where 10y = x. The input x must be greater
than 0.
Figure 96
© Honeywell
Function 73: Log Base 10 (Advanced VLC only)
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Function 74: nth Root (Advanced VLC only)
Description The nth root of x is the value y such that y raised to the nth power
equals x.
Use an integer for n. The output is the value y where yn = x. The
input x must be greater than or equal to 0.
Remarks
Figure 97
164
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Chapter 6 | DDC function reference
Function 75: Exponential (Advanced VLC only)
Description ex is the number e (approximately 2.71828128) raised to the x
power.
Figure 98
© Honeywell
Function 75: Exponential (Advanced VLC only)
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Function 76: Sunrise/Sunset Calculator (Advanced VLC only)
Description Calculates sunrise and sunset time in decimal degrees using
latitude and longitude inputs. The current date is used as an implicit input to this
function.
Remarks The function returns correct values only if the current date is set
correctly. All times are specified in minutes since midnight.
Figure 99
Function 76: Sunrise/Sunset Calculator (Advanced VLC only)
Note Coordinated universal time (UTC) offset must be set correctly in the
Device Profile in Device Manager.
Latitude should be in the range -90 to +90 degrees, where + indicates North
latitude, - indicates South latitude. Longitude should be in the range -360 to
+360 degrees, where + indicates East longitude, - indicates West longitude.
The outputs Always Up and Always Down are always FALSE unless the latitude
is above the Arctic circle or below the Antarctic circle, in which case they
indicate TRUE if the sun either does not set or not rise, respectively.
Example Where is zero? Longitude 0 degrees passes through the original site of
the Royal Observatory in Greenwich, England. Seattle’s latitude is entered in
decimal degrees as 47.617,-122.333 (47° 37’ N, 122° 20’ W). Using the
specified latitude and longitude, the current local date/time/UTC offset, and
Daylight Saving Status are taken into consideration. This function generally runs
only at midnight, but it also runs on change of latitude, longitude, system date/
time, UTC offset, to Daylight Saving Status.
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Figure 100
Latitude and longitude
Figure 101
© Honeywell
Function 76: example of use
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Function 77: Daily Schedule (Advanced VLC only)
Description Calculates the daily schedule from ON, OFF, and Current Time
inputs.
This function compares the current minutes before or after midnight against
desired ON and OFF times. The purpose of this function is to determine when to
turn a load ON or OFF at a given time on a daily basis.
Inputs are handled modulo 1440 (60 minutes x 24 hours, the number
of minutes in a day). All times are expressed in digits that represent the number
of minutes either before midnight (using a negative digit) or after midnight
(using a positive digit). Midnight (12:00 A.M.) can be represented either by 0 or
by 1440.
Remarks
Therefore, for programming purposes, each minute of the day can be expressed
as either a positive or negative digit, as shown in the examples below:
• 11:50 P.M. can be expressed as either -10 or as 1350.
• 6:05 A.M can be expressed as either -1075 or as 365.
• 11:32 A.M can be expressed as either -748 or as 692.
• 12:00 P.M. (noon) can be expressed as -720 or as 720.
The ON and OFF times need not be in any order. The output must be binary.
This function is more complex than a normal comparator function because it
works for cases where the ON time is at the end of the day and when the OFF
time is at the beginning of the day. such as for outdoor lighting applications.
Output
Current Time < OFF Time < ON Time
TRUE
Current Time < ON Time < OFF Time
FALSE
ON Time < Current Time < OFF Time
TRUE
OFF Time < Current Time < ON Time
FALSE
Figure 102
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Function 77: Daily Schedule
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Chapter 6 | DDC function reference
Example The figure below shows a DDC with a typical lighting application for
parking lot lights. The lights turn on half an hour before sunset and turn off half
and hour after sunrise.
Figure 103
Function 77 example: parking lot lights
You can also use Function 78: Convert to HHMM to display sunrise and sunset
times by using Envision for BACtalk. (See Figure 105 on page 170.)
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Function 78: Convert to HHMM (advanced VLC only)
Description Converts time to HHMM format from Time input. Converts
minutes since midnight to either 12- or 24-hour HH:MM format.
Remarks HH24 = The hour of day for a 24-hour clock, 0-24.
MM = Minutes past the current hour, 0-59.
HH12 = The hour of day for a 12-hour clock, 1-12.
PM = This flag determines AM or PM for the 12-hour clock.
All times are specified in minutes since midnight.
The input is considered modulo 1440 (60 minutes x 24 hours, the number of
minutes in a day).
Figure 104
Function 78: Convert to HHMM (Advanced VLC only)
Use Function 78 to indicate the sunrise and sunset times on an Envision for
BACtalk display or template. To display time in 24-hour format, use only HH24
and MM. To display time in 12-hour format, use only HH12, MM, and PM.
BV is displayed as a read-only property with active text set to PM and inactive
text set to AM.
Figure 105 shows how to use Function 76: Sunrise/Sunset Calculator and
Function 78: Convert to HHMM to display the sunrise and sunset times in either
12- or 24-hour format.
Figure 105
170
Figure 78 example: displaying sunrise and sunset times
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Chapter 6 | DDC function reference
Data Writer
Description The Data Writer is not a function but a tool. Use it with
VisualLogic DDC drawings only (not the DDC Editors) for presetting values to
be written to a controller during a DDC download or update values while
troubleshooting in Live Data View mode.
Remarks For the Data Writer, you must specify the controller I/O point (data
point) to write to. Additionally, you can set values for points to be inserted into
the device during a DDC view live data troubleshooting session.
Downloading DDC
To configure, right-click the data writer function and enter the following data.
 Data Value:
• Value - this is the value that you want to write to the controller I/O
point. What you enter here depends on your Type selection. For Real
numbers, enter any value with up to six significant digits of resolution.
For Boolean values, enter ON or OFF.
• Type - this is the type of value you want to write. Select Real to write a
real number (usually for analog values). Select Boolean to write an ON
or OFF value (usually for binary values). Select Null to write a Null
value (with Null selected, Value is unavailable).
 I/O Data Point:
• Object - this is the object in the controller to which you want to write
the value. You can select AO, AV, BO, or BV.
• Instance - this is the instance of the object to write. For example, if you
select BO as the object, and 1 as the instance, the value is written to
BO-1.
• Property - select either the present-value or the priority-array. This
property is written to the property of the Object and Instance.
• Index - If you select priority-array as the Property, this determines the
index of the priority-array that is written. If you select present-value for
Property, and the object you are writing to supports the priority-array,
the value is written to the present-value using the priority array index
specified. For example, with BO-1, present-value selected as the
controller I/O point, and an Index of 8, the value is actually written to
priority-array Index. For objects that don’t support the priority-array
property, Index is ignored.
Troubleshooting DDC
After the data writer function is configured, you must right-click on the function
again and select Write Data to write the data to the device.
0
VALUE
I/O Data Point
DATA WRITER
Figure 106
© Honeywell
Writing data to a device
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Object and property reference
7
This chapter lists the objects in BACtalk unitary, global, and expandable
controllers followed by a reference to the properties of those objects. Use this list
to interpret the source and nature of system data.
BACtalk expandable controller
This section lists the objects in a BACtalk expandable controller, followed by a
reference to the properties of those objects. Use this list to interpret the source and
nature of system data.
Note the following conventions that are used in the tables below:
• The W column indicates whether the property is writable. Properties
without a check mark in this column are read-only. Some items can only
be written to through special setup. These are checked as writable and
noted under Remarks.
• In the Example column, items in Boldface always appear as listed for that
item. For example, the object-type property of a device object always
returns the word “Device” to the Envision for BACtalk display.
• The Type column indicates a BACnet data type. Unsigned and Signed
indicate integer values; enumerated indicates an enumerated value table;
other data types may exist.
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Objects in the VLX controller
Ta ble 30
VLX objects
Object (instance range)
Function
AI (0-7999)
Analog input objects associated with physical, universal input terminals on EXPs. AIs are
identified as AI-e0nn, where e is the EXP address (0-7) and nn is the input terminal number.
AO (0-7999)
Analog output objects associated with physical output terminals on EXPs. AOs are identified as
AO-e0nn, where e is the EXP address (0-7) and nn is the output terminal number.
AV (0–7999)
RESERVED AVs for EXP configuration, status, and backup values. Do not use these AVs for
general programming or automation. These AVs do not support the priority-array property.
AV (8000–8499)
General use AVs. These AVs support the priority-array property.
BI (0-7999)
Binary input objects associated with physical, universal input terminals on EXPs. BIs are
identified as BI-e0nn, where e is the EXP address (0-7) and nn is the input terminal number.
BO (0-7999)
Binary output objects associated with physical output terminals on EXPs. BOs are identified as
BO-e0nn, where e is the EXP address (0-7) and nn is the output terminal number.
BV (8000-8499)
General use BVs. These BVs support the priority-array property.
Calendar
Describes a list of calendar dates, special event dates, holiday dates, and date ranges.
Device
Provides general information about a device.
Event Enrollment
Defines an event and connects the occurrence of the event to the transmission of an event
notification. Used in BACtalk primarily for alarms.
File (0)
Provides information about the real-time operating code (ROC) file.
File (1024)
Provides information about the current DDC file.
File (2048)
Provides information about DDC trap file.
Notification Class
Stores a list of available recipients for the distribution of event notifications (alarms, trendlog
gathering, and so on).
Program 0
Stores information about the ROC/controller program.
Program 1024
Stores program status information about the current DDC program.
Schedule
Controls designated properties by periodic schedule that may recur during a range of dates.
Properties of VLX AI objects
Ta ble 31
Properties of the VLX AI object
Property
W
Type
cov-increment

Real
description

Character string
Return Air
Temp
event-state
Enumerated
NORMAL
object-identifier
BACnet_ Object_
Identifier
AI 5
object-name
Character string
EXP 7 AI 05
object-type
Enumerated
AI
174
Example
Remarks
If the present value changes by this amount or greater, a
change-of-value notification is sent to subscribed
devices. Not used at present.
An editable description of the object’s location or
function.
This property consists of the object-type property and the
object instance, which is a numeric code that identifies
the object of interest.
Indicates an analog input (AI) object.
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Ta ble 31
Properties of the VLX AI object (Continued)
Property
W
Type
Example
Remarks
out-of-service

Boolean
FALSE
TRUE decouples the present-value property from the
physical input, and the present value does not track
further physical input changes. While TRUE, the present
value can be changed to any value to simulate
conditions for testing. FALSE indicates that the present
value is tracking changes to the physical input.
present-value

Real
72.3
Writable only when out-of-service = TRUE (see herein).
Range of present value depends on input setup. See
“Setting inputs, outputs, and other function parameters”
on page 55.
reliability
BACnet_ Reliability
NO FAULT
DETECTED
Other possibility is UNRELIABLE_OTHER which
indicates a loss of communication between the VLX and
EXP.
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Enumerated
Deg F
Indicates the unit of measure for the AI, in BACnet
engineering units.

units
Properties of VLX AO objects
Ta ble 32
Properties of VLX AO objects
Property
W
Type
Example
Remarks
description

Character string
Economizer
Damper
An editable description of the object’s location or
function.
event-state
Enumerated
NORMAL
object-identifier
BACnet_ Object_
Identifier
AO 5
object-name
Character string
EXP 0 AO
00
object-type
Enumerated
AO
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
out-of-service

Boolean
FALSE
TRUE decouples the present-value property from the
physical output. While TRUE, the present value can be
changed to any value to simulate conditions for testing
without affecting the actual physical output.
present-value

REAL
75
Valid values are real numbers in the range 0–100.
Values greater than 100 are interpreted as 100. When
commanded, values are written to the present value with
a priority for writing, which corresponds to a priorityarray index (see “priority-array” herein).
BACnet Priority
Array
<Array of
BACnet
Priority
Value>
An array of prioritized values (indexes 1-16) controlling
the present value, index 1 having the highest priority.
The value with the highest priority for writing controls the
present value. Possible values for priority-array indexes
are real values or NULL. A NULL value indicates no
command is issued at that priority level.
priority-array
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Ta ble 32
Properties of VLX AO objects (Continued)
Property
W
reliability
relinquish-default

status-flags

units
Type
Example
Remarks
BACnet_ Reliability
NO FAULT
DETECTED
Other possibilities are OVER RANGE, UNDER RANGE,
UNRELIABLE_OTHER.
REAL
0
Default value to be used for present-value property
when all priority-array indexes are NULL.
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Enumerated
%
Indicates the AO’s unit of measure in BACnet
engineering units.
Example
Remarks
Properties of VLX AV objects
Ta ble 33
Properties of VLX AV objects
Property
W
Type
cov-increment

Real
description

Character string
Occupied
Setpoint
event-state
Enumerated
Normal
object-identifier
BACnet_ Object_
Identifier
AV 1
object-name
Character string
object-type
Enumerated
AV
out-of-service
Boolean
FALSE
Real
76.4
Range is3 x 1038 (six significant digits of resolution).
Bit string
<Bit string>
A four-position bit string that indicates the status of the
AV. If a status bit =1, that status is TRUE.
Enumerated
Deg F
Indicates the unit of measure, in BACnet engineering
units, for the AV present value.
BACnet
PriorityArray
<Array of
BACnet
PriorityValue>
NOT AVAILABLE IN AVs (0-7999). GENERAL
PURPOSE AVs ONLY. An array of prioritized values
(indexes 1-16) controlling the present value, index 1
having the highest priority. The value with the highest
priority controls the present value. Possible values for
priority-array indexes are real values or NULL. A NULL
value indicates no command is issued at that priority
index.
REAL
0
NOT AVAILABLE IN AVs (0-7999). GENERAL
PURPOSE AVs ONLY. Default value to be used for
present-value property when all priority-array indexes
are NULL.
present-value

status-flags
units

priority-array
relinquish-default
176

If the present value changes by this amount or greater,
a change-of-value notification is sent to subscribed
devices. Not used at present.
A description assigned to describe the object’s function.
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
For reserved AVs, shows the EXP and AV of interest.
For example, EXP 0 AV 01. Otherwise shows AV
<instance>.
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Properties of VLX BI objects
Ta ble 34
Properties of the VLX BI object
Property
W
Type
Example
Remarks
description

Character string
Fan Status
An editable description of the object’s location or
function.
event-state
Enumerated
NORMAL
object-identifier
BACnet_ Object_
Identifier
BI 10
object-name
Character string
BI 10
object-type
Enumerated
BI
Indicates a binary input (BI) object.
Boolean
FALSE
TRUE decouples the present-value property from the
physical input, and the present value does not track
further physical input changes. While TRUE, the present
value can be changed to any value to simulate
conditions for testing. FALSE indicates that the present
value is tracking changes to the physical input.
out-of-service

polarity
present-value
NORMAL

Logical state
reliability
status-flags
© Honeywell
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Bit string
ACTIVE
ACTIVE or INACTIVE. Writable only when out-of-service
= TRUE (see herein).
NO FAULT
DETECTED
Other possibility is UNRELIABLE_OTHER.
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
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Properties of VLX BO objects
Ta ble 35
Properties of the VLX BO object
Property
W
Type
Example
Remarks
description

Character string
Fan Start/
Stop
An editable description of the object’s location or
function.
event-state
Enumerated
Normal
If the object does not support intrinsic reporting, the
value is NORMAL.
object-identifier
BACnet_ Object_
Identifier
BO 1
This property consists of the object-type property and the
object instance, which is a numeric code that identifies
the object of interest.
object-name
Character string
BO 01
object-type
Enumerated
BO
out-of-service

Boolean
FALSE
TRUE decouples the present-value property from the
physical output. While TRUE, the present value can be
changed to any value to simulate conditions for testing
without affecting the actual physical output.
present-value

Enumerated
INACTIVE
Either ACTIVE or INACTIVE. Note that a NULL value
can be written to the present value on data displays, but
the value is actually written to a priority-array property.
The present value is the result of the priority array.
priority-array
BACnet Priority
Array
<Array of
BACnet
Priority
Value>
A read-only array of prioritized values (1-16) controlling
the present value, priority 1 having the highest priority.
The value with the highest priority controls the present
value. Possible values for priority-array indexes are
ACTIVE, INACTIVE, or NULL. A NULL value indicates
no command is issued at that priority level.
reliability
BACnet_ Reliability
NO FAULT
DETECTED
Other possibility is UNRELIABLE_OTHER.
Enumerated
INACTIVE
Default value used for present-value property when all
priority-array values are NULL.
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Example
Remarks
relinquish-default

status-flags
Properties of VLX BV objects
Ta ble 36
Properties of VLX BV objects
Property
W
Type
active-text
description
event-state
ON

Character string
Occupied
Setpoint
Enumerated
NORMAL
inactive-text
OFF
object-identifier
BACnet_ Object_
Identifier
BV 8413
object-name
Character string
BV 8413
object-type
Enumerated
BV
178
A description assigned for the object’s function.
This property consists of the object-type property and the
object instance, which is a numeric code that identifies
the object of interest.
Indicates a binary value (BV).
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Ta ble 36
Properties of VLX BV objects (Continued)
Property
W
Type
Example
Boolean
FALSE
Enumerated
INACTIVE
Either ACTIVE (ON) or INACTIVE (OFF).
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
priority-array
BACnet
PriorityArray
<Array of
BACnet
PriorityValue>
An array of prioritized values (indexes 1-16) controlling
the present value, index 1 having the highest priority.
The value with the highest priority controls the present
value. Possible values for priority-array indexes are
ACTIVE, INACTIVE, or NULL. A NULL value indicates
no command is issued at that priority-array index.
REAL
0
Default value to be used for present-value property when
all priority-array indexes are NULL.
out-of-service

present-value
relinquish-default

Remarks
Properties of the VLX device object
Ta ble 37
Properties of the VLX device object
Property
Type
Example
Remarks
apdu-segment- timeout 
Unsigned
6000
The time after transmission of a “segment” until the lack
of a reply means it was assumed to be lost (in
milliseconds, 1000 = 1 sec). Default = 6000.

Unsigned
6000
The time after transmission of an APDU until the lack of
a reply means it was assumed to be lost. The APDU
time-out value for this device in milliseconds (1000 = 1
sec). Default = 6000.
Character string
VLX V1.0
Indicates the ROC file version.
apdu-timeout
W
application-softwareversion
daylight-savingsstatus

Boolean
FALSE
Indicates whether daylight savings is in effect (TRUE) or
not (FALSE). Not used at present.
description

Character string
Second floor
controller
Assigned by the user to describe the device’s function.
device-addressbinding
List
Empty.
firmware-revision
Character string
BACtalk VLX
v1.1 02/02/
2002
Indicates the VLX boot code version.
local-date

Date
Sunday, 02/
24/2002
Indicates date: day of the week, month/day/year.
Writable through Time Sync.
local-time

Time
10:15:56.00
am
Indicates the time stored in the device. Writable through
Time Sync.
location

Character string
East Wing
Indicates the physical location of the device.
Unsigned
1476
The maximum message packet size that the device can
handle.
Unsigned
60
Number of MS/TP messages the device sends per token
hold. Default = 60. Max. = 200.
Unsigned
127
Highest MAC address (above this unit's) that another
MS/TP master should be set to.
max-apdu-lengthaccepted
max-info-frames
max-master
© Honeywell
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Ta ble 37
Properties of the VLX device object (Continued)
Property
W
Type
Example
Remarks
Character string
VLX
controller
Assigned by the vendor to indicate the device model.
Unsigned
3
The number of times a message is resent after it is
assumed to be lost.
object-identifier
BACnet_ Object_
Identifier
Device 200
This property consists of the object-type property and
the device instance, which is a numeric code that
identifies the device of interest.
object-list
Array
object-name
Character string
Controller
200
object-type
Enumerated
Device
protocolconformance-class
Unsigned
3
Integer from 1–6 indicating the conformance class of the
device. A device must support a standardized set of
services and object types to claim a particular class
conformance.
protocol-object-typessupported
Bit string
<Bit string>
An internally used bit string. Indicates which BACnet
object types reside in the device.
protocol-servicessupported
Bit string
<Bit string>
An internally used bit string. Indicates which BACnet
services the device can process.
protocol-version
Unsigned
1
Indicates the version of the BACnet protocol supported
by the device.
segmentationsupported
Enumerated
segmented
both
Device is capable of segmenting both transmission and
reply messages.
system-status
Enumerated
Operational
Other possible values are operational-read-only,
download-required, download-in-progress, nonoperational.
Signed
0
Coordinated Universal Time offset, in minutes. Not used
at present.
vendor-identifier
Unsigned
18
A unique code assigned by ASHRAE to the
manufacturer, in this case, Alerton.
vendor-name
Character string
Alerton
Indicates the device manufacturer.
model-name
number-of-apduretries
utc-offset
180


An array whose elements list the object-identifier
properties of all objects the device supports.
No two devices are permitted to have the same object
name.
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Chapter 7 | Object and property reference
Properties of VLX event-enrollment objects
Ta ble 38
Properties of VLX event-enrollment objects
Property
W
Type
Example
Remarks
acked-transitions

bit string
To-offnormal
=1
To-fault = 1
To-normal =
1
Indicates whether the corresponding transitions have
been acknowledged. A 1 indicates that the transition was
acknowledged.
description

Character string
Event
enrollment 0
A description assigned to describe the object’s function.
event-enable

bit string
To-offnormal
=1 , To-fault
= 1, Tonormal = 1
Indicates whether notifications are enabled for these
event transition types. A 1 indicates that the transition is
reported. Set in the Event Enrollment Editor at the
operator workstation.
event-parameters
BACnetEvent
Parameter
change_of_
bitstring
event-state
Enumerated
NORMAL
Indicates the current state of the event.
Enumerated
CHANGE_OF
_BITSTRING
Indicates the type of event algorithm to be used to detect
events.
issue-confirmednotifications
Boolean
TRUE
Determines whether confirmed or unconfirmed
notifications are used when a notification-class object
isn’t used (that is, a recipient is specified). Set in the
Event Enrollment Editor at the operator workstation.
notification-class
Enumerated
1
Indicates the notification class to be used for event
transitions. Set in the Event Enrollment Editor at the
operator workstation.
notify-type
Unsigned
alarm
Indicates whether the object is set up for alarms or
events.
object-identifier
BACnet_ Object_
Identifier
Eventenrollment
0
Consists of the object-type property and the object
instance, which is a numeric code that identifies the
object of interest.
Character string
Alarm
Assigned at the operator workstation.
Boolean
FALSE
Indicates whether the file has been saved for backup.
event-type

object-name
object-propertyreference

object-type
priority
Eventenrollment

Unsigned
9
Priority for issuing event notifications.
process-identifier
Unsigned
3
A numeric identifier for a handling process in the
recipient device. Set in the Event Enrollment Editor at
the operator workstation.
recipient
Enumerated
<>
Unused.
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Properties of VLX file objects
Ta ble 39
Properties of VLX file objects
Property
W
Type
Example
Remarks
archive

Boolean
FALSE
Indicates whether the file has been saved for backup.
description

Character string
VLX ROC
File
A description assigned to describe the object’s function.
file-access-method
Enumerated
stream
access
file-size
Unsigned
983040
The size of the file, in bytes.
file-type
Character string
ROC
Also DDC or TRAP.
modification-date
Time
4/29/1997
10:22:20:00a
The date and time the file was last modified.
object-identifier
BACnet_ Object_
Identifier
file 0
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
File 0
object-type
Enumerated
file
read-only
Boolean
TRUE
Indicates whether the file can be written to by BACnet
services.
Properties of VLX notification-class objects
Ta ble 40
Properties of VLX notification-class objects
Property
W
Type
Example
Remarks
ack-required

Bit string
To offnormal
= 1, to fault =
1, to normal
=1
Indicates whether an acknowledgment is required for
event transitions. A 1 indicates that acknowledgment is
required. Set up at the operator workstation.
description

Character string
Alarm
Handler
An editable description of the object’s location or
function.
notification-class
Unsigned
1
Echoes the object instance.
object-identifier
BACnet_ Object_
Identifier
Notification
-class 1
This property consists of the object-type property and the
object instance, which is a numeric code that identifies
the object of interest.
Character string
Alarm
Handler 1
Enumerated
Notificationclass
<List of
BACnet
Destination>
object-name

object-type
recipient-list

List
priority

Array of Unsigned
182
Lists the devices that receive notification when the
notification class transitions. Set up at the operator
workstation.
Indicates the priority to be used for event notifications for
TO-OFFNORMAL, TO-FAULT, and TO-NORMAL
events, respectively.
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Chapter 7 | Object and property reference
Properties of VLX program objects
Ta ble 41
Properties of VLX program objects
Property
W
Type
Example
Remarks
description

Character string
Occupied
Setpoint
A description assigned to describe the object’s function.
description-of-halt
Character string
Program
halted by
request
instance-of
Character string
alerton hq
alerVLX
0*00000000*
Header information for the file. Program 0 does not
support this property.
object-identifier
BACnet_ Object_
Identifier
program
1024
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
Program
Object 1024
object-type
Enumerated
Program
Boolean
FALSE
Enumerated
READY
Used to command the program state. A program can be
stopped using the HALT command, for example, and
started again with RESTART.
program-location
Character string
DDC
Sequence =
60
Set when program stops.
program-state
Enumerated
RUNNING
Possible states include RUNNING, IDLE, HALTED.
reason-for-halt
Enumerated
PROGRAM
reliability
Enumerated
NO FAULT
DETECTED
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
out-of-service
program-change

A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Properties of VLX schedule objects
Ta ble 42
Properties of VLX schedule objects
Property
W
Type
Example
Remarks
description

Character string
Weekend
Gym
A description assigned to describe the object’s function.
effective-period

Sequence
<BACnet
DateRange>
Assigned in schedule setup at the operator workstation.
exception-schedule

Sequence
<Array of
BACnet
Special
Event>
Assigned in schedule setup at the operator workstation.
list-of-object-propertyreferences

List
<List of
BACnet
Object
Property
Reference>
The list of objects that this schedule commands.
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Ta ble 42
Properties of VLX schedule objects (Continued)
Property
W
object-identifier
object-name

object-type
present-value

priority-for-writing

weekly-schedule

184
Type
Example
Remarks
BACnet_ Object_
Identifier
schedule 0
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Character string
schedule
000
Assigned in schedule setup at the operator workstation.
Enumerated
schedule
ACTIVE
Indicates the value most recently written to a referenced
object property. May be analog, binary, or other,
depending on the controlled property.
Unsigned
16
Assigned in schedule setup at the operator workstation.
Sequence
<Array of
BACnetDaily
Schedule>
Assigned in schedule setup at the operator workstation.
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 7 | Object and property reference
BACtalk global controller
This section lists the objects in a BACtalk global controller (this includes the
BACtalk control modules (BCMs) which act as global controllers in the
BACtalk system), followed by a reference to the properties of those objects. Use
this list to interpret the source and nature of system data. See the BACtalk
Control Modules Installation and Operations Guide (LTBT-TM-BCMIOG) for
information about virtual objects and properties that appear in the BCM-TUX
module.
Note the following conventions that are used in the tables below:
• The W column indicates whether the property is writable. Properties
without a check mark in this column are read-only. Some items can only
be written to through special setup. These are checked as writable and
noted under Remarks.
• In the Example column, items in boldface always appear as listed for
that item. For example, the object-type property of a device object
always returns the word “Device” to the Envision for BACtalk display.
• The Type column indicates a BACnet data type. Unsigned and Signed
indicate integer values; enumerated indicates an enumerated value table;
other data types may exist.
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Objects in global controllers
Ta ble 43
Objects in global controllers
Object
Function
Range of Present Value
AV (0-999)
General Use AVs.
3.40282 x 1038 (six significant digits
of resolution)
AV(10000-10279)
Reserved AVs. These AVs do not support the priority-array
property. Available in BACtalk Control Modules only.

The present-value property of the diagnostic AVs listed are
reserved to provide operating information about the BCM.
You can reference these present values on data displays or
in DDC to assist in troubleshooting and fault detection.
See the BACtalk Control Modules Installation and Operations
Guide (LTBT-TM-BCMIOG) for more information about these
AVs.
BV (0–999)
Binary values. These BVs support the priority-array property.
ACTIVE or INACTIVE
Calendar
Describes a list of calendar dates, special event dates,
holiday dates, and date ranges.
N/A
Communication Failure
Object
Defines a communication alarm event for a specific controller
and connects the event to the transmission of an event
notification. Used in EBT for generating alarms when
communication loss is detected.
Demand Limiter
Proprietary Alerton object for demand limiting function.
Device
Provides general information about a device.
Event Enrollment
Defines an event and connects the occurrence of the event
to the transmission of an event notification. Used in BACtalk
primarily for alarms.
File 0
Stores information about the ROC file in a controller.
File 1024
Stores file information about the current DDC program.
File 2048
DDC trap file.
Notification Class
Stores a list of available recipients for the distribution of event
notifications (alarms, trendlog gathering, etc.).
Program 0
Stores information about the ROC/controller program.
Program 1024
Stores program status information about the current DDC
program.
Schedule
Controls designated properties by periodic schedule that may
recur during a range of dates.
Zones
Proprietary Alerton object containing the individual properties
and references required to support the optimum start and
tenant activity features of Envision for BACtalk.
Trendlogs
Proprietary Alerton object for trendlog function.
186
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0-100 (ramp value)
© Honeywell
Chapter 7 | Object and property reference
Properties of a global controller AV object
Ta ble 44
Properties of a global controller AV object
Property
W
Type
cov-increment
ü
Real
description
ü
Character string
Occupied
Setpoint
event-state
Enumerated
Normal
object-identifier
BACnet_ Object_
Identifier
AV 1
object-name
Character string
AV 001
object-type
Enumerated
AV
out-of-service
Boolean
False
Real
76.4
Range is3 x 1038 (six significant digits of resolution).
status-flags
Bit string
<Bit string>
A four-position bit string that indicates the status of the
AV. If a status bit =1, that status is TRUE.
units
Enumerated
Deg F
Indicates the unit of measure, in BACnet engineering
units, that the AV is expressed in.
present-value
ü
Example
Remarks
If the present value changes by this amount or greater, a
change-of-value notification is sent to subscribed
devices.
A description assigned to describe the object’s function.
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Properties of a global controller BV object
Ta ble 45
Properties of a global controller BV object
Property
W
Type
Example
Remarks
description
ü
Character string
Occupied
Setpoint
A description assigned for the object’s function.
event-state
Enumerated
NORMAL
object-identifier
BACnet_ Object_
Identifier
BV 1
object-name
Character string
BV 001
object-type
Enumerated
BV
out-of-service
Boolean
FALSE
Enumerated
INACTIVE
Either ACTIVE (ON) or INACTIVE (OFF).
status-flags
Bit string
In alarm = 0
fault = 0
overridden = 0,
out of service =
0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
out of service
Boolean
FALSE
Either ACTIVE (ON) or INACTIVE (OFF)
present-value
© Honeywell
ü
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Indicates a binary value (BV).
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Ta ble 45
Properties of a global controller BV object (Continued)
Property
W
priority array
relinquish default

Type
Example
Remarks
BACnet
PriorityArray
<Array of
BACnet
PriorityValue>
An array of prioritized values (indexes 1-16) controlling
the present value, index 1 having the highest priority.
The value with the highest priority controls the present
value. Possible values for priority-array indexes are
ACTIVE, INACTIVE, or NULL. A NULL value indicates
no command is issued at that priority-array index.
REAL
0
Default value to be used for present-value property
when all priority-array indexes are NULL.
Properties of a global controller calendar object
Ta ble 46
Properties of a global controller calendar object
Property
W
Type
Example
Remarks
date-list

List
<List of
BACnet
Calendar
Entry>
List of calendar dates.
description

Character string
Holidays
1997
A description assigned to describe the object’s function.
BACnet_Object_
Identifier
calendar 1
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Character string
calendar
001
Enumerated
calendar
Boolean
FALSE
object-identifier

object-name
object-type

present-value
TRUE if the current date is in the date list; FALSE if it is
not.
Properties of a global controller demand limiter object
Ta ble 47
Properties of a global controller demand limiter object
Property
W
object-identifier
object-name

object-type
Type
Example
Remarks
BACnet_Object_
Identifier
demand
limiter 1
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Character String
BACnet_Object_
Type
aler-enabled

BOOLEAN
True if the demand limiter is enabled; False if it’s
disabled.
aler-max-enabledisable-ramp-step

Real
Valid range is 1 to 100%.
description

Character String
aler-demand-window

Unsigned
aler-anticipationfactor

Real
188
The total number of minutes in the demand window.
Range is 1 to 60 minutes.
3
Valid range is 1.0 to 10.0.
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Chapter 7 | Object and property reference
Ta ble 47
Properties of a global controller demand limiter object (Continued)
Property
W
Type
Example
Remarks
aler-meter-inputs

BACnet Array 1 of
BACtalk Meter Input
<List of
meter
inputs>
The list of meter inputs to the demand limiter. Currently
limited to one meter input.
units

Character String
Indicates the measurement units of
aler_instantaneous_demand.
aler-instantaneousdemand
Real
Reflects the current reading from the meter (after
applying conversion factors).
aler-average-demand
Real
The larger of two calculated averages: Average Demand
Window and Average Anticipation Interval (if not set to
1.0).
aler-ramp-control

BACtalk Device
Object Property
Reference or Value
The input that identifies the ramp parameters.
aler-ramp-parameters

BACtalk Ramp
Parameters
The shed ramp parameters.
aler-ramp-value
Real
The current ramp value (0-100%). This number is
calculated whether the demand limiter object is enabled
or not.
aler-active-ramp
Real
The current ramp value (0-100%) being used to control
loads. This value is between zero and the
Aler_Ramp_Value. The exact value depends on
whether the demand limiter object is enabled or
disabled.
aler-binary-loads

BACnet Array 5 of
BACtalk Binary
Shed Level
The list of binary loads.
aler-custom-binaryloads

List of BACtalk
Binary Loads
The list of custom binary loads.
aler-binary-loadstatus
List of BACtalk
Demand Load
Status
The status of each binary and custom binary load.
aler-total-binary-loads
Unsigned
The total number of binary and custom binary loads.
aler-binary-loadsshed
Unsigned
The total number of binary and custom binary loads that
have been shed.
aler-total-analogloads
Unsigned
The number of defined analog loads.
aler-analog-loadsin-shed
Unsigned
The total number of analog loads that have been shed.
aler-analog-loads
List of BACtalk
Analog Loads
The list of analog loads.
aler-analog-loadstatus
List of BACtalk
Demand Load
Status
The status of each analog load.
aler-recent-history
List of BACtalk
Demand History
Sample
A list of historical data with the most recent data first.
out-of-service
BOOLEAN
© Honeywell
FALSE
Not currently used so always set to False.
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Properties of a global controller device object
Ta ble 48
Properties of a global controller device object
Property
W
Type
Example
Remarks
APDU-segmenttimeout

Unsigned
2000
The time after transmission of a “segment” until the
lack of a reply means it was assumed to be lost (in
milliseconds, 1000 = 1 sec).
APDU-timeout

Unsigned
3000
The time after transmission of an APDU until the lack
of a reply means it was assumed to be lost. The APDU
timeout value for this device in milliseconds (1000 = 1
sec).
Character string
BCM-Eth
controller 2.5
(build 10)
Indicates the ROC version.
application-softwareversion
daylight-savings-status

Boolean
FALSE
Indicates whether daylight savings is in effect (TRUE)
or not (FALSE).
description

Character string
Second floor
controller
Assigned by the user to describe the device’s function.
device-addressbinding
List
firmware-revision
Character string
BCM-Eth
Loader 2.5
(build 9)
Indicates the firmware version.
local-date
Octet String
Wednesday,
5/14/1997
Indicates date: day of the week, month/day/year.
local-time
Time
10:15:56.00a
m
Indicates the time stored in the device.
Character string
East Wing
Indicates the physical location of the device.
Unsigned
1476
The maximum message packet size that the device
can handle.
Unsigned
200
(maximum
number)
Number of MS/TP messages the BCM-Eth sends per
token hold.
max-master
Unsigned
127
The highest MS/TP MAC address the BCM-Eth
attempts to pass the token to.
model-name
Character string
BCM-Eth
controller
Assigned by the vendor to indicate the device model.
Unsigned
3
The number of times a message is resent after it is
assumed to be lost.
object-identifier
BACnet_ Object_
Identifier
Device 200
This property consists of the object-type property and
the device instance (a numeric code that identifies the
device) of the device of interest.
object-list
Array
object-name
Character string
object-type
Enumerated
protocol-conformanceclass
Unsigned
location

max-APDU-lengthaccepted
max-info-frames
number-of-APDUretries
190


Inaccessible.
An array whose elements list the object-identifier
properties of all objects the device supports.
Controller 200
No two devices are permitted to have the same object
name.
Device.
3
Integer from 1–6 indicating the conformance class of
the device. A device must support a standardized set
of services and object types to claim a particular class
conformance.
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 7 | Object and property reference
Ta ble 48
Properties of a global controller device object (Continued)
Property
W
Type
Example
Remarks
protocol-object-typessupported
Bit string
<Bit string>
An internally used bit string. Indicates which BACnet
object types reside in the device.
protocol-servicessupported
Bit string
<Bit string>
An internally used bit string. Indicates which BACnet
services the device can process.
protocol-version
Unsigned
1
Indicates the version of the BACnet protocol supported
by the device.
segmentationsupported
Enumerated
segmented
both
Device is capable of segmenting both transmission
and reply messages.
system-status
Enumerated
operational
Other possible values are operational-read-only,
download-required, download-in-progress, nonoperational.
Signed
0
Coordinated Universal Time offset, in minutes.
vendor-identifier
Unsigned
18
A unique code assigned by ASHRAE to the
manufacturer.
vendor-name
Character string
Alerton
Indicates the device manufacturer.

utc-offset
Properties of a global controller event-enrollment object
Ta ble 49
Properties of a global controller event enrollment object
Property
W
Type
Example
Remarks
acked-transitions

Bitstream
To-offnormal
=1 , To-fault
= 1, Tonormal = 1
Indicates whether the corresponding transitions have
been acknowledged. A 1 indicates that the transition was
acknowledged. Set in the Event Enrollment Editor at the
operator workstation.
description

Character string
Event
enrollment 0
A description assigned to describe the object’s function.
event-enable

Bitstream
To-offnormal
=1 , To-fault
= 1, Tonormal = 1
Indicates whether notifications are enabled for these
event transition types. A 1 indicates that the transition is
reported. Set in the Event Enrollment Editor at the
operator workstation.
event-parameters
Time
<BACnet
Event
Parameter>
Determines the method used to monitor the referenced
object.
event-state
Boolean
TRUE
Indicates whether the file can be written to by BACnet
services.
change of
state
Indicates the type of event to be monitored and reported.
event-type

issue-confirmednotifications
Boolean
TRUE
Determines whether confirmed or unconfirmed
notifications are used when a notification class object
isn’t used (that is, a recipient is specified). Set in the
Event Enrollment Editor at the operator workstation.
notification-class
Enumerated
1
Indicates the notification class to be used for event
transitions. Set in the Event Enrollment Editor at the
operator workstation.
notify-type
Unsigned
alarm
Indicates whether the object is set up for alarms or
events.
object-identifier
BACnet_ Object_
Identifier
Eventenrollment 0
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
© Honeywell
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Ta ble 49
Properties of a global controller event enrollment object (Continued)
Property
W
object-name
object-propertyreference

Type
Example
Remarks
Character string
Alarm
Assigned at the operator workstation.
Boolean
FALSE
Indicates whether the file has been saved for backup.
object-type
eventenrollment
priority
Unsigned
9
Priority for issuing event notifications. Set in the Event
Enrollment Editor at the operator workstation.
process-identifier
Unsigned
3
A numeric identifier for a handling process in the
recipient device. Set in the Event Enrollment Editor at
the operator workstation.
recipient
Enumerated
<>
Properties of a global controller file object
Ta ble 50
Properties of a global controller file object
Property
W
Type
Example
Remarks
archive

Boolean
FALSE
Indicates whether the file has been saved for backup.
description

Character string
BCM-Eth
ROC File
A description assigned to describe the object’s function.
file-access-method
Enumerated
stream
access
file-size
Unsigned
983040
The size of the file, in bytes.
file-type
Character string
ROC
Also DDC or TRAP.
modification-date
Time
4/29/1997
10:22:20:00
a
The date and time the file was last modified.
object-identifier
BACnet_ Object_
Identifier
file 0
This property consists of the object-type property and the
object instance, which is a numeric code that identifies
the object of interest.
object-name
Character string
File 0
object-type
Enumerated
file
read-only
Boolean
TRUE
192
Indicates whether the file can be written to by BACnet
services.
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 7 | Object and property reference
Properties of a global controller notification class object
Ta ble 51
Properties of a global controller notification class object
Property
W
Type
Example
Remarks
ack-required

Bit string
To offnormal
= 1, to fault =
1, to normal
=1
Indicates whether an acknowledgment is required for
event transitions. A 1 indicates that acknowledgement is
required. Set up at the operator workstation.
description

Character string
Alarm
Handler
An editable description of the object’s location or
function.
notification-class
Unsigned
1
Echoes the object instance.
object-identifier
BACnet_ Object_
Identifier
Notificationclass 1
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Character string
Alarm
Handler 1
Enumerated
Notificationclass
List
<List of
BACnetDesti
nation>

object-name
object-type

recipient-list
Lists the devices that receive notification when the
notification class transitions. Set up at the operator
workstation.
to-fault-priority
Unsigned
Indicates the priority used for event notifications, 0–255.
Lower numbers indicate a higher priority.
to-normal-priority
Unsigned
Indicates the priority used for event notifications, 0–255.
Lower numbers indicate a higher priority.
to-offnormal-priority
Unsigned
Indicates the priority used for event notifications, 0–255.
Lower numbers indicate a higher priority.
Properties of a global controller program object
Ta ble 52
Properties of a global controller program object
Property
W
Type
Example
Remarks
description

Character string
Occupied
Setpoint
A description assigned to describe the object’s function.
description-of-halt
Character string
Program
halted by
request
instance-of
Character string
alerton hq
alerbti
0*00000000*
Header information for the file. Program 0 does not
support this property.
object-identifier
BACnet_ Object_
Identifier
program
1024
This property consists of the Object_Type property and
the Object Instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
Program
Object 1024
object-type
Enumerated
Program
out-of-service
Boolean
FALSE
Enumerated
READY
program-change
© Honeywell

Used to command the program state. A program can be
stopped using the HALT command, for example, and
started again with RESTART.
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Ta ble 52
Properties of a global controller program object (Continued)
Property
W
Type
Example
Remarks
program-location
Character string
DDC
Sequence =
60
Set when program stops.
program-state
Enumerated
RUNNING
Possible states include RUNNING, IDLE, HALTED.
reason-for-halt
Enumerated
PROGRAM
reliability
Enumerated
NO FAULT
DETECTED
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Properties of a global controller schedule object
Ta ble 53
Properties of a global controller schedule object
Property
W
Type
Example
Remarks
description

Character string
Weekend
Gym
A description assigned to describe the object’s function.
effective-period

Sequence
<BACnet
DateRange>
Assigned in schedule setup at the operator workstation.
exception-schedule

Sequence
<Array of
BACnet
Special
Event>
Assigned in schedule setup at the operator workstation.
list-of-object-propertyreferences

List
<List of
BACnet
Object
Property
Reference>
The list of objects that this schedule commands.
BACnet_ Object_
Identifier
schedule 0
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Character string
schedule
000
Assigned in schedule setup at the operator workstation.
Enumerated
schedule
object-identifier
object-name

object-type
present-value

priority-for-writing

weekly-schedule

194
ACTIVE
Indicates the value most recently written to a referenced
object property. May be analog, binary, or other,
depending on the controlled property.
Unsigned
16
Assigned in schedule setup at the operator workstation.
Sequence
<Array of
BACnetDaily
Schedule>
Assigned in schedule setup at the operator workstation.
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 7 | Object and property reference
Properties of a global controller zone object
Ta ble 54
Properties of a global controller zone object
Property
W
object-identifier
object-name

object-type
aler-reference-device

aler-weekly-scheduleinputs
aler-weekly-scheduleobject

aler-holiday-scheduleinput
aler-holiday-scheduleobject

aler-event-schedule
-inputs
Type
Example
Remarks
BACnetObject
Identifier
Uniquely identifies the object within the BACnet device.
Character string
Assigned during zone setup at the operator workstation.
BACnetObjectType
A BACnetObjectType of the value BT_Zone.
BACnetObject
Identifier
A BACnetObjectIdentifier indicating the primary BACnet
device referenced through the zone object.
Array [n] of
BACnetPriorityValue
This array works exactly like a priority array and allows
up to [n] schedule objects to write weekly schedule
commands to the zone.
Array [n] of
BACtalkOptionalDev
ObjRef
An array that points to the schedule objects used for
weekly schedules.
BACnetPriorityValue
The value last written by the holiday schedule. If
Aler_Holiday_Schedule_Object contains a NULL value,
this property is also set to NULL.
BACtalkOptionalDev
ObjRef
A reference to the schedule object that writes to
Aler_Holiday_Schedule_Input.
Array [n] of
BACnetPriorityValue
This array works exactly like a priority array and allows
up to [n] schedule objects to write weekly schedule
commands to the zone.
An array that points to the schedule objects used for
event schedules.
aler-event-schedule
-objects

Array [n] of
BACtalkOptionalDev
ObjRef
priority-for-writing

Unsigned
present-value

BACtalkZoneState
units

BACnetEngineering
Units
aler-persistence-rate

Unsigned
aler-refresh

BACnetPriorityValue
aler-refresh-rate

Unsigned
13
Contains the priority at which commands are written to
the referenced properties:
Day_Night_Command_Reference,
Aler_Warmup_Command_Reference, and
Aler_Cooldown_Command_Reference.
The default is 13; acceptable range is 1-16.
Occupied
Alerton Enumerated type that reflects the current state of
the zone: Occupied, Unoccupied, Warmup, Cooldown,
or Tenant Override.
A value that indicates the unit of measure for all
temperatures in the zone object.
300
A value indicating the number of seconds between
refresh times for controlled command points in the zone:
occupied, warmup, and cooldown command points.
Writes to this value refreshes all referenced properties.
This includes input and output values.
60
A value indicating when referenced data is old and
should be refreshed. If the data is accessed and it hasn’t
been updated in the time (number of seconds) indicated
here, it is immediately refreshed.
Values are limited in the range of 10-900 seconds.
NOTE: Data is refreshed every 15 minutes minimum.
aler-optimum-startmode
© Honeywell

BACtalkOptimum
StartMode
An enumerated type indicating the algorithm used by
optimum start: None, Manual, or Automatic.
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Ta ble 54
Properties of a global controller zone object (Continued)
Property
W
Type
Example
Remarks
aler-maximumadvance-time
Unsigned
240
A value representing the maximum number of minutes to
begin optimum start operations in advance of the next
scheduled occupied time. The default value is 240; valid
range is 1-1440.
aler-oa-temp-reference
BACtalkDevObjProp
RefOrValue
The reference that indicates the outside air temperature
to use in optimum start calculations.
aler-oa-temp-value
Real
A real value as read from the aler-oa-temp-reference.
aler-humidityreference
BACtalkDevObjProp
RefOrValue
A value or reference that indicates the humidity value
used in optimum start calculations.
aler-humidity-value
BACnetPriorityValue
A value which is read from the aler-humidity-reference.
aler-oa-limit

Real
65.0
A real value used in optimum start calculations for
heating operations. The default value is 65.0.
aler-building-mass

Real
4.0
A real value that indicates the amount of desired
temperature change. Values are limited between 0-10.
aler-warmup-factor
Real
1.0
A real value used in warmup calculations for a zone.
This value is adjusted each time warmup mode is
initiated. Valid range is 0-10. A 0 (zero) disables warmup
calculations.
aler-cooldown-factor
Real
1.0
A real value used in cooldown calculations for a zone.
This value is adjusted each time cooldown mode is
initiated. Valid range is 0-10. A 0 (zero) disables
cooldown calculations.
aler-alt-warmup-factor
Real
An alternate value used for the warmup factor when the
zone was not occupied during the previous 24 hours. Set
to NULL to disable alternate warmup.
aler-alt-cooldownfactor
Real
An alternate value used for the cooldown factor when
the zone was not occupied during the previous 24 hours.
Set to NULL to disable alternate cooldown.
aler-tuning-factor
Real
A real value that determines how aggressive the system
should self-tune the warmup and cooldown factors.
aler-coolingtemperature-rate
Real
A real value that indicates the rate (in degrees per hour)
that the cooldown mode is expected to change the
temperature of the zone when in manual optimum start
mode.
aler-heatingtemperature-rate
Real
A real value that indicates the rate (in degrees per hour)
that the warmup mode is expected to change the
temperature of the zone when in manual optimum start
mode.
aler-occupiedcommand-value
BACnetBinaryPV
aler-occupiedcommand-reference
BACtalkDevObjProp
RefOrValue
aler-warmupcommand-value
BACnetBinaryPV
aler-warmupcommand-reference
BACtalkDevObjProp
RefOrValue
aler-cooldowncommand-value
BACnetBinaryPV
aler-cooldowncommand-reference
BACtalkDevObjProp
RefOrValue
196
active
Active is written to this value when the zone is occupied.
If the zone is unoccupied or in warmup or cooldown
mode, Inactive is written to this value.
Active is written to this value when the zone is in warmup
mode. Otherwise, Inactive is written.
Active is written to this value when the zone is in
cooldown mode. Otherwise, Inactive is written.
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 7 | Object and property reference
Ta ble 54
Properties of a global controller zone object (Continued)
Property
W
Type
Example
Remarks
aler-zone-temp-value
Real
aler-zone-tempreference
BACtalkDevObjProp
RefOrValue
aler-occupied-heatingsetpoint-value
Real
aler-occupied-heatingsetpoint-reference
BACtalkDevObjProp
RefOrValue
aler-occupied-coolingsetpoint-value
Real
aler-occupied-coolingsetpoint-reference
BACtalkDevObjProp
RefOrValue
aler-tenant-overridereference
BACtalkDevObjProp
RefOrValue
aler-tenant-overridevalue
BACnetBinaryPV
aler-tenant-actrecipient
BACnetRecipient
Indicates the device to which tenant override events are
sent. A NULL value prevents tenant override events from
being sent.
aler-diagnostics
CharacterString
A formatted character string indicating the current status
of the zone object and its operation.
description
CharacterString
A string of characters describing the zone.
zone-command-mode
BACtalkZoneComm
andMode
Indicates whether it’s a binary or multistate object.
0=binary and 1=multistate.
zone-main-truth-table
Array [3] of
BACtalkZoneTruth
TableEntry
Indicates the value to be written to each of the three
main output points for each of the four possible modes of
operation. The array elements are mapped as follows.
Indicates the current zone temperature. The default is a
reference to AV101.
The heating setpoint to use in optimum start
calculations.
The cooling setpoint to use in optimum start calculations.
Indicates that the zone is in tenant override mode.
Element 1= Defines the values written to aler-occupiedcommand-reference.
Element 2= Defines the values written to aler-warmupcommand-reference.
Element 3= Defines the values written to aler-cooldowncommand-reference.
Even though each entry is the table is a
BACnetPriorityValue type, only Unsigned values may be
written to the table elements. In all cases, the zone
object writes values of the correct data type (unsigned
for multistate mode and BinaryPV in all other cases)
when sending commands.
If a property reference is NONE, then the corresponding
array element is ignored. It is good practice to write a
zero into the array element in this case.
© Honeywell
LTBT-TM-PRGRMR Rev. 13
197
Programmer’s Guide and Reference | BACtalk Systems
BACtalk VLC
This section lists the objects in BACtalk VLCs, followed by a reference to the
properties of those objects. Use this list to interpret the source and nature of
system data.
Note the following conventions that are used in the tables below:
• The W column indicates whether the property is writable. Properties
without a check mark in this column are read-only. Some items can only
be written to through special setup. These are checked as writable and
noted under Remarks.
• In the Example column, items in boldface always appear as listed for
that item. For example, the object-type property of a device object
always returns the word “Device” to the Envision for BACtalk display.
• The Type column indicates a BACnet data type. Unsigned and Signed
indicate integer values; enumerated indicates an enumerated value table;
other data types may exist.
Objects in BACtalk VLCs
Ta ble 55
Objects in BACtalk VLCs
Object
Function
Range of Present Value
Remarks
AI (0-15)
Associated with physical input
terminals. Number of inputs
varies with VLC model.
0–4095 in counts
Input setup and scaling done in VLC DDC or
VisualLogic. AI-1 corresponds to input terminal
IN-1, and so on.
AI inputs are scanned just prior to every 0.1
second pass of DDC.
AI (100-107)
Diagnostic AIs to aid in
troubleshooting
Reserved exclusively for VLCA-1688.
Only the present value of these objects is
available. These present value properties can
be viewed by placing a read-only item on a
data display. The properties cannot be used in
DDC.
AI inputs are scanned just prior to each pass of
DDC.
AI 99
(All VLCs
except the
VLCA-1688.)
When the supply voltage connected to the VLC
is 24 VAC, AI-99 has a value of 40.6 VDC. The
value of AI-99 is filtered in software to screen
out electrical noise. AI-99 varies proportionally
with the voltage of the 24 VAC supply power to
the VLC, which in turn is proportional to the
supply voltage to the transformer. AI-99 can be
used in DDC to detect brownouts and limit
operation of compressors or other voltage
sensitive equipment if appropriate. You can
also set up trendlogs for AI-99 to track longer
term variations in power supply voltage.
In Gen4 VLCs, AI-99
represents the unregulated DC
voltage resulting from
rectification of the 24 volt AC
supply voltage.
AI inputs are scanned just prior to every 0.1
second pass of DDC.
AI-109
198
Gen4 VLC, 4.10b4 and later
only
0-192
LTBT-TM-PRGRMR Rev. 13
Indicates number of text strings used in RAM.
Reserved for object name and description
properties of AI, AO, AV, BI, BO and BV
objects.
© Honeywell
Chapter 7 | Object and property reference
Ta ble 55
Objects in BACtalk VLCs (Continued)
Object
Function
Range of Present Value
Remarks
AO (0-7)
Physical analog output.
0–100
AO present-value property is the result of the
priority array.
AO outputs are refreshed every 0.1 second
following each DDC pass. The Present Value
is resolved from its priority array at this time.
When a write to the output occurs during DDC,
the Present Value of the object is not affected
until after the DDC pass is complete.
AV (0-107)
AV (108-299)
(VLCA-1688
only)
Real numbers not directly
associated with physical input
or output terminals. Typically
used for setpoints and
intermediate calculations.
3 x 1038
Six significant digits of resolution. All AVs are
used in RAM and backed up in Flash memory
on loss of power.
IMPORTANT: 90–107 reserved for Microset
use. In C3 VLCs, AVs 0–49 stored in VLC
RAM, and 50–89 stored in VLC EEPROM.
May not be backed up in RAM. See VLC 1688
Installation and Operations Guide (LTBTVLCA1688IOG) for more information about the
VLCA-1688.
General purpose analog
points.
Real numbers not directly
associated with physical input
or output terminals. Typically
used for setpoints and
intermediate calculations.
NOTE: AV 250-299 have a priority array.
AV (250-255)
Provide read/write access to
airflow calibration data in
VAV-series VLCs.
0-102.3
Although non-VAV controllers have these
objects, only VAV controllers use them.
BI (0-15)
Associated with physical input
terminals. Number of inputs
varies with VLC model.
ACTIVE or INACTIVE
BIs correspond to the same input terminals as
AIs. BI-1 corresponds to input terminal IN-1,
and so ON. The BI turns ON when the
associated AI drops to a value in counts less
than or equal to 448. It reads OFF when the AI
rises to a value in counts greater than or equal
to 512. The BI does not change state while the
value is in the range 449–512.
BI inputs are scanned just prior to every 0.1
second pass of DDC.
BO (0-15)
Physical binary output.
ACTIVE or INACTIVE
BO present-value property is the result of the
priority array.
BO outputs are refreshed every 0.1 second
following each pass of DDC. The Present
Value is resolved from its priority array at this
time. When a write to the output occurs during
DDC, the Present Value of the object is not
affected until after the pass of DDC is
complete.
BV (0–84)
Binary value.
ACTIVE or INACTIVE
BV 0-63 are for general use. BV 64-84 are
reserved for Microset control.
BV 40 is refreshed every 0.1 second following
each pass of DDC. The Present Value is
resolved from its priority array at this time.
When a write to the output occurs during DDC,
the Present Value of the object is not affected
until after the pass of DDC is complete.
BV (200-215)
(VLCA-1688
and VLD-362
only)
© Honeywell
Control AI current/voltage/
resistance mode.
ACTIVE or INACTIVE
LTBT-TM-PRGRMR Rev. 13
See Table 72 on page 212 for more details.
199
Programmer’s Guide and Reference | BACtalk Systems
Ta ble 55
Objects in BACtalk VLCs (Continued)
Object
Function
Range of Present Value
Remarks
BV (300-303)
(VLC-444
only)
Current/voltage mode.
ACTIVE or INACTIVE
Read-only. ACTIVE indicates AOs have
detected current mode (load is 550 Ohms or
less). INACTIVE indicates voltage mode (load
is 1K Ohm or higher).
BV (300-307)
(VLCA-1688
only)
Control AI current/voltage/
resistance mode.
ACTIVE or INACTIVE
See Table 72 on page 212 for more details.
BV (400-403)
(VLC-444
only)
Enables the resistor on AIs.
ACTIVE or INACTIVE
Gets set to default value from DDC header at
beginning of first DDC pass, allowing DDC to
override the default.
BV (400-415)
(VLCA-1688
only)
Enables the resistor on AIs.
ACTIVE or INACTIVE
Gets set to default value from DDC header at
beginning of first DDC pass, allowing DDC to
override the default.
BV (85-299)
(VLCA-1688
only)
General purpose BVs.
BV (88-95)
(VAViH only)
VAViH-SD DIP switch settings.
BV (99)
(VLC-444
only)
BV 250 -299 support the priority array. NOTE:
BV 200-215 are reserved for control of analog
input modes. See Table 71 on page 212.
ACTIVE or INACTIVE
See VLC Installation and Operations Guide
(LTBT-TM-GEN4VLC) for details. See
Table 67 on page 210.
ACTIVE or INACTIVE
Disables the 0.5 degrees F deadband between
AV-95 and AV-96. Allows AV-96 to equal AV95 if turned ON.
Can reference only objects on the same device
(inside the box).
Calendar
(VLCA-1688
only)
Describes a list of calendar
dates, special event dates,
holiday dates, and date
ranges.
N/A
Device
Provides general information
about device.
N/A
Event
enrollment
(VLCA-1688
only)
Defines an event and connects
the occurrence of the event to
the transmission of an event
notification.
File 0
Provides information about the
DDC program file.
N/A
File 1
Provides information about the
DDC trap file.
N/A
MV (0-9)
(VLCA-1688
only)
List of number values with
associated state text for each
possible value.
MV(300-307)
(VLCA-1688
only)
Indicate AO HOA switch
positions.
1-3
1=Hand
2=Off
3=Auto
MV(350-357)
(VLCA-1688
only)
Indicate BO HOA switch
positions.
1-3
1=Hand
2=Off
3=Auto
Notification
Class
(VLCA-1688
only)
Stores a list of available
recipients for the distribution of
event notifications (alarms,
trendlog gathering, and so on).
Program 0
Provides information about
DDC program execution.
200
Used in BACtalk primarily for alarms.
General purpose use.
The number of notification classes is limited by
memory.
N/A
LTBT-TM-PRGRMR Rev. 13
© Honeywell
Chapter 7 | Object and property reference
Ta ble 55
Objects in BACtalk VLCs (Continued)
Object
Function
Range of Present Value
Remarks
Schedule
(VLCA-1688
only)
Controls designated properties
by periodic schedule that may
recur during a range of dates.
N/A
Can only reference objects on the same device
(inside the box). The number of schedules is
limited by memory - typically 3 schedules with
50 events each.
Trendlog
(VLCA-1688
only)
Helps troubleshoot problem
areas and identify critical
operating trends in the BACnet
system.
VLCA trendlogs can only reference internal
objects and notification classes. The maximum
number of trendlogs is limited by memory typically 50 trendlogs with 10 days of data
retention.
Properties of the VLC AI object
Ta ble 56
Properties of the VLC AI object
Property
W
Type
Example
Remarks
description

Character string
Return Air
Temp
An editable description of the object’s location or
function.
event-state
Enumerated
object-identifier
BACnet_ Object_
Identifier
AI 5
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
AI 05
On Advanced VLC, AI 005
object-type
Enumerated
AI
Indicates an analog input (AI) object.
out-of-service
Boolean
FALSE
Real
72.3
Range of present value goes from 0–4000 as input
voltage goes from 0–5.12VDC.
reliability
BACnet_ Reliability
NO FAULT
DETECTED
Other possibilities are OVER RANGE, UNDER
RANGE, UNRELIABLE_OTHER.
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden = 0
out of service
=0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Enumerated
Deg F
Indicates the unit of measure, in BACnet engineering
units, that the AI is expressed in.
present-value
units
© Honeywell


Normal.
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Properties of the VLC AO object
Ta ble 57
Properties of the VLC AO object
Property
Type
Example
Remarks
aler_interface_value
(VLCA-1688 MV
300-307 only)
REAL
75
Shows the actual AO state, which may differ from
Present_Value because of HOA switch position and
initial 20 second hold-off.
aler_ao_hand_value
(VLCA-1688
MV300-307 only)
REAL
75
Shows the current HOA potentiometer position,
regardless of the current HOA state.
Character string
Economizer
Damper
An editable description of the object’s location or
function.
event-state
Enumerated
NORMAL
object-identifier
BACnet_ Object_
Identifier
AO 1
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
AO 01
On Advanced VLC, AO001
object-type
Enumerated
AO
out-of-service
Boolean
FALSE
Options are TRUE or FALSE. If TRUE, the physical
output is decoupled from the AO and its present value,
and internal DDC execution alone determines the status
of the physical output.
REAL
75
Valid values are real numbers in the range 0–100.
Values greater than 100 are interpreted as 100. When
commanded from a data display, values are actually
written to the priority array (see priority-array entry
herein) and read back from the present value for display.
priority-array
BACnet
PriorityArray
<Array of
BACnet
Priority
Value>
A read-only array of prioritized values (1-16) controlling
the present value, priority 1 having the highest priority.
The value with the highest priority controls the present
value. Possible values for priority array indexes are real
values or NULL. A NULL value indicates no command is
issued at that priority level.
reliability
BACnet_ Reliability
NO FAULT
DETECTED
Other possibilities are OVER RANGE, UNDER RANGE,
UNRELIABLE_OTHER.
REAL
0
Default value to be used for present-value property
when all priority-array indexes are NULL. Set up in DDC
or VisualLogic.
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Enumerated
%
Indicates the unit of measure, in BACnet engineering
units, that the AO is expressed in. Set in VLC DDC or in
VisualLogic.
description
present-value
relinquish-default
W



status-flags
units
202

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Chapter 7 | Object and property reference
Properties of the VLC AV object
Ta ble 58
Properties of the VLC AV object
Property
W
Type
Example
Remarks
description

Character string
Static
Pressure
Setpoint
An editable description of the object’s location or
function.
event-state
Enumerated
NORMAL
object-identifier
BACnet_Object_
Identifier
AV 15
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
AV 15
On Advanced VLC, AV 015
object-type
Enumerated
AV
Indicates an analog value (AV) object.
out-of-service
Boolean
FALSE
Real
0.02

present-value
Real number in the range  3 x 1038 with six significant
digits of resolution.
reliability
(VLCA-1688 only)
BACnet_ Reliability
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Enumerated
%
Indicates the unit of measure, in BACnet engineering
units, that the AV is expressed in. Set in VLC DDC or in
VisualLogic.

units
no-fault-detected
Properties of the VLC BI object
Ta ble 59
Properties of the VLC BI object
Property
W
Type
Example
Remarks
description

Character string
Fan Status
An editable description of the object’s location or
function.
event-state
Enumerated
NORMAL
object-identifier
BACnet_ Object_
Identifier
BI 10
object-name
Character string
BI 10
object-type
Enumerated
BI
out-of-service
Boolean
FALSE
polarity
present-value
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
Indicates a binary input (BI) object.
NORMAL

Logical state
ACTIVE
ACTIVE or INACTIVE.
reliability
BACnet_ Reliability
NO FAULT
DETECTED
Used only in VLCA-1688.
status-flags
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
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Properties of the VLC BO object
Ta ble 60
Properties of the VLC BO object
Property
W
Type
Example
Remarks
Enumerated
INACTIVE
Shows the actual BO state, which may differ from
present_value because of HOA switch position and
initial 20-second hold-off.
Character string
Fan Start/
Stop
An editable description of the object’s location or
function.
event-state
Enumerated
Normal
If the object does not support intrinsic reporting, the
value shall be NORMAL.
minimum_off_time
(VLCA-1688 only)
Unsigned32
10
Anticycle setting defined in DDC header. Units are
seconds. Active only when a .bd6 file is being used.
minimum_on_time
(VLCA-1688 only)
Unsigned32
10
Anticycle setting defined in DDC header. Units are
seconds. Active only when a .bd6 file is being used.
object-identifier
BACnet_ Object_
Identifier
BO 1
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
BO 01
On Advanced VLC, BO001
object-type
Enumerated
BO
out-of-service
Boolean
FALSE
polarity
(VLCA-1688 only)
Enumerated
NORMAL
Enumerated
INACTIVE
Either ACTIVE or INACTIVE. Note that a NULL value
can be written to the present value on data displays, but
the value is actually written to a priority-array property.
The present value is the result of the priority array.
priority-array
BACnet
PriorityArray
<Array of
BACnet
Priority
Value>
A read-only array of prioritized values (1-16) controlling
the present value, priority 1 having the highest priority.
The value with the highest priority controls the present
value. Possible values for priority-array indexes are
ACTIVE, INACTIVE, or NULL. A NULL value indicates
no command is issued at that priority level.
reliability
BACnet_ Reliability
NO FAULT
DETECTED
Other possibilities are OVER RANGE, UNDER RANGE,
UNRELIABLE_OTHER.
Enumerated
INACTIVE
Default value used for present-value property when all
priority-array values are NULL. Set up in DDC or
VisualLogic.
Bit string
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
aler_interface_value
(VLCA-1688 only)
description
present-value
relinquish-default
status-flags
204



Options are TRUE or FALSE. If TRUE, the physical
output is decoupled from the BO and its present value,
and internal DDC execution alone determines the status
of the physical output.
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Properties of the VLC BV object
Ta ble 61
Properties of the VLC BV object
Property
W
Type
Example
Remarks
description

Character string
Test Mode
An editable description of the object’s location or
function.
event-state
Enumerated
Normal
object-identifier
BACnet_ Object_
Identifier
BV 20
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object-name
Character string
BV 20
On Advanced VLC, BV020
object-type
Enumerated
BV
out-of-service
Boolean
FALSE
Enumerated
INACTIVE

present-value
reliability
(VLCA-1688 only)
BACnet_ Reliability
status-flags
Bit string
Either ACTIVE or INACTIVE.
no-fault-detected
In alarm = 0,
fault = 0,
overridden =
0, out of
service = 0
A four-position bit string that indicates the status of the
object. If a status bit =1, that status is TRUE.
Properties of the VLC file object
Ta ble 62
Properties of the VLC file object
Property
W
Type
Example
Remarks
archive

Boolean
FALSE
Indicates whether some sort of backup file has been
created (TRUE) or not (FALSE). Set manually.
description
Character string
Generic
Generic
v0011
Data from program information in the DDC header.
file_access_method
Enumerated
stream
access
file_size
Unsigned
6885
file_type
Character string
VLC DDC
Program File
modification_date
Time
Wednesday,
5/29/1997
10:22:20:00
a
Date and time that the DDC file was downloaded to the
VLC.
object_identifier
BACnet_ Object_
Identifier
file 0
This property consists of the object-type property and
the object instance, which is a numeric code that
identifies the object of interest.
object_name
Character string
VLC DDC
Program File
object_type
Enumerated
file
read_only ??
Boolean
TRUE
© Honeywell
Size of the file, in bytes.
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Properties of the VLC device object
Ta ble 63
Properties of the VLC device object
Property
W
Type
Example
Remarks
active_cov_subscriptions
List of
BACnetCOVSubscri
ption
aler_devinfo
Octet string
used by Envision for BACtalk to get device
information
aler_dst_end_date

BACnetCalendarEnt
ry
Default = “First Sunday in November”
aler_dst_end_time

Time
Default = “2:00 AM”
aler_dst_mode

Enumeration
Default = “Date range”
aler_dst_start_date

BACnetCalendarEnt
ry
Default = “Second Sunday in March”
aler_dst_start_time

Time
Default = “2:00 AM”
APDU-timeout

Unsigned
0
The time after transmission of an APDU until
the lack of a reply means it was assumed to
be lost. The APDU timeout value for this
device in milliseconds (1000 = 1 sec).
Character string
AZ 60 V 4.10b4
Indicates the ROC version.
Character string
Mechanical room
controller
An editable description that identifies the
device’s location or function.
application-softwareversion
description

device-address-binding
List
Inaccessible.
firmware-revision
Character string
RLZ0e VLC
0120306031130
Indicates the firmware version and serial
number of controller. Unique number assigned
to hardware.
local-date

Octet String
Wednesday, 5/14/
2002
Indicates date: day of the week, month/day/
year.
local-time

Time
10:15:56.00am
Indicates the time stored in the device.
location

Character string
East Wing
Indicates the physical location of the device.
max-APDU-lengthaccepted
Unsigned
206
The maximum message packet size that the
device can handle.
max-info-frames
Unsigned
1
Number of MS/TP messages the VLC sends
per token hold.
max-master
Unsigned
127
The highest MS/TP MAC address the VLC
attempts to pass the token to.
model-name
Character string
VLC controller
Assigned by the vendor to indicate the device
model.
Unsigned
0
The number of times a message is resent after
it is assumed to be lost.
object-identifier
BACnet_ Object_
Identifier
Device 200
This property consists of the object-type
property and the device instance of the device
of interest.
object-list
Array
number-of-APDU- retries
object-name
206


An array whose elements list the objectidentifier properties of all objects the device
supports.
Character string
Device 200
LTBT-TM-PRGRMR Rev. 13
No two devices are permitted to have the
same object name.
© Honeywell
Chapter 7 | Object and property reference
Ta ble 63
Properties of the VLC device object (Continued)
Property
W
Type
Example
Remarks
object-type
Enumerated
Device
protocol_conformance_
class
(not in VLCA-1688)
Unsigned
3
Integer from 1–6 indicating the conformance
class of the device. A device must support a
standardized set of services and object types
to claim a particular class conformance.
protocol-conformanceclass
Unsigned
3
Integer from 1–6 indicating the conformance
class of the device. A device must support a
standardized set of services and object types
to claim a particular class conformance.
protocol_object_types_
supported
Bit string
<Bit string>
A bit string that indicates the BACnet object
types that reside in the device. A 1 indicates
the device is present.
protocol_revision
(VLCA-1688 only)
Unsigned
4
protocol_services_
supported
Bit string
<Bit string>
A bit string that indicates the BACnet services
the device can process. A 1 indicates that
service is supported.
protocol_version
Unsigned
1
Indicates the version of the BACnet protocol
supported by the device.
segmentation_supported
Enumerated
No segmentation
VLCs do not support segmentation.
system_status
Enumerated
Operational
Other possible values are operational-readonly, download-required, download-inprogress, non-operational.
utc_offset
(VLCA-1688 only)
Integer
-480
Default is 0.
vendor_identifier
Unsigned
18
A unique code assigned by ASHRAE to the
manufacturer.
vendor_name
Character string
Alerton
Indicates the device manufacturer.
Properties of the VLC program object
Ta ble 64
Properties of the VLC program object
Property
Type
Example
Remarks
description
Character string
Generic Generic
V0011 P8223001
Data from program information in DDC or in
VisualLogic. Format is <rep> <job> <program
name> <revision> <displaynum>.
instance_of
Character string
Generic Generic
V0011 P8223001
Echoes the description property.
object_identifier
BACnet_ Object_
Identifier
program 0
This property consists of the object-type property
and the object instance, which is a numeric code
that identifies the object of interest.
object_name
Character string
VLC DDC program
object_type
Enumerated
program
out_of_service
Boolean
FALSE
© Honeywell
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Ta ble 64
Properties of the VLC program object (Continued)
Property
W
Type
Example
Remarks
program_change

Enumerated
READY
One can use this property to manipulate the
Program State property. Doing this is not
recommended.
program_state
Enumerated
RUNNING
Possible states include RUNNING, IDLE,
HALTED.
reliability
BACnet_ Reliability
no fault detected
Other possibilities are OVER RANGE, UNDER
RANGE, UNRELIABLE_OTHER.
status_flags
Bit string
In alarm = 0, fault =
0, overridden = 0,
out of service = 0
A four-position bit string that indicates the status
of the object. If a status bit =1, that status is
TRUE.
Reserved objects
The tables below describe reserved objects for various controllers.
Microset/Microtouch Reserved AVs and BVs in BACtalk VLCs
Note In the VLCA-1688, these objects can be writable and or defined in the
DDC header. In other VLCs, they are read-only.
Ta ble 65
Microset/Microtouch Reserved AVs and BVs in BACtalk VLCs
Point
Object name
Remarks
AV 90
Setpoint (SP)
Occupant-selected space temperature (Deg F/C)
setpoint. May be written to in DDC.
AV 91
Setpoint High Limit
Value of AV-90 cannot exceed this value. Deg F/C Limit
0...127
AV 92
Setpoint Low Limit
Value of AV-90 cannot be below this value. Deg F/C
Limit 0...AV 91
AV 93
Cooling SP Offset
Added to the value of AV-90 in calculation of AV-99.
Deg F/C Limit 0...20 Degrees F (0...11.1 Degrees C)
AV 94
Heating SP Offset
Subtracted from the value of AV-90 in calculation of
AV-100. Deg F/C Limit 0...20 Degrees F (0...11.1
Degrees C)
AV 95
Unoccupied Cooling SP
Deg F/C Limit 45.5 Degrees F...99 Degrees F.
(7.2...37.2 Degrees C)
AV 96
Unoccupied Heating SP
Deg F/C
BV 99 OFF:
Limit 45 Degrees F(AV 95 minus 0.5 Degrees F) or 7.2
Degrees C (AV95 0.28 Degrees C)
BV 99 ON:
Limit 45 Degrees F... AV95
AV 97
After Hours Timer Limit
Override timer limit. After-hours override timer limit is in
hours—3.5 = three hours 30 minutes. Housekeeping
timer limit is in minutes--3.5 = 3 minutes 30 seconds.
Hours Limit 0.0...9.9
AV 98
After Hours Timer
After-hours/housekeeping override timer value. Resets
to 0 when BV-64 is ON. Hours in half hour increments.
Value set to 0.0 in case of power failure. Limit 0.0...AV
97
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Chapter 7 | Object and property reference
Ta ble 65
Microset/Microtouch Reserved AVs and BVs in BACtalk VLCs (Continued)
Point
Object name
Remarks
AV 99
Current Cooling SP
Equal to AV-95 while unoccupied (BV-67 OFF). Deg
F/C. AV-90 + AV-104 + AV-93 + AV-106
AV 100
Current Heating SP
Equal to AV-95 while unoccupied (BV-67 OFF).Deg F/C.
AV-90 + AV-104 - AV-94 - AV-106
AV 101
Microset Room Temp.
Space Temperature to display. Range is 0-127 F (-18-53
C). Display at Microset/Microset II (written to in DDC).
AV 102
Space Humidity
Humidity, read directly from Microset II humidity sensor.
Applies only to units with optional humidity sensor (MS2000-BTH). %RH. Microset/Microset II option.
AV 103
Outside Air Temp. to Microset
Deg F/C. Outside air temperature (OAT) to display on
Microset II. Temperature range is -99–127°F (-73–
53°C). AV-104. Display at Microset/Microset II (written to
in DDC)
AV 104
MicroTouch Lever Offset
Not used in Microset II. Microtouch lever offset. Deg F/C.
SP Offset due to current MT lever position
AV 105
MicroTouch Lever Value
Not used in Microset II. Microtouch bias limit. Deg F/C.
SP Offset when MT lever is at full swing. Limit 0...20
Degrees F (0...11.1 Degrees C)
AV 106
Demand Offset
Deg F/C Limit 0...15 Degrees (0...8.3 Degrees C)
AV 107
Outside Humidity
Outside humidity (in %RH) to display on Microset
II.%RH. Display at Microset/Microset II (written to in
DDC)
BV 64
Time Schedule Output
Written to in VLC DDC - typically from BV-40. On: Sets
microset II to occupied or rented (vacant) operation. Off:
Sets Microset II to unoccupied.
BV 65
Select ON-OFF Mode
Enable Microset/Microset II ON/OFF mode
BV 66
After Hours Timer Status
ON when override timer (AV-98) is nonzero.
BV 67
Occupied/Unoccupied Status
Selects occupied or unoccupied setpoints as current.
ON = occupied
BV 68
Field Service Lockout
OFF = Field Service and balance mode enabled
BV 69
Swap English/ Metric
ON overrides DDC mode selection (BV-71) at Microset/
Microset II Display
BV 70
Microtouch (OFF) / Metric (ON)
ON if Microset/Microset II is detected
BV 71
English (ON) / Metric (OFF)
DDC header, metric/english mode selection.
On=English units.
BV 72
Fan Low Speed
Set by user from Microset/Microset II
BV 73
Fan Medium Speed
Set by user from Microset/Microset II
BV 74
Fan High Speed
Set by user from Microset/Microset II
BV 75
Door Open ICON
N/A
BV 76
Fan Auto
N/A
BV 77
Heating ICON
Display heating icon on Microset II
BV 78
Cooling ICON
Display cooling icon on Microset II
BV 79
Backlight ON
Turn Microset II LCD backlight ON continuously or only
in response to button activity
BV 80
Enable Fan Speed Control
Allow Microset II user to control fan speed
BV 81
Select Hotel Mode
Select Hotel Mode (Microset II) vs Office Mode
© Honeywell
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Ta ble 65
Microset/Microtouch Reserved AVs and BVs in BACtalk VLCs (Continued)
Point
Object name
Remarks
BV 82
Enable Time Display
Display time on Microset II
BV 83
24Hr Time Format
Select time format, 24-hour or 12-hour, for display on
Microset II
BV 84
Enable Space Humidity
Room humidity display on Microset II
BV 99
Available only for the VLC-444. Disable
Unoccupied SP Deadband.
Disables the 0.5 Degrees F deadband between AV 95
and AV 96. Allows AV 96 to equal AV 95 if turned ON.
VLD-362 reserved BVs
Ta ble 66
VLD-362 reserved BV objects
Point
Object name
Remarks
BV (300-301)
BV nnn
Read-only. “Active” indicates AO 0 to AO 1 have
detected current mode (load is 550 Ohms or less).
“Inactive” indicates voltage mode (load is 1K Ohm or
higher).
BV (400-402)
BV nnn
Enables the 4.22K pull-up on AI 0 to AI 2 (with room for
AI 4 to AI 31). Gets set to default value from DDC
header at beginning of first DDC pass, allowing DDC to
override the default.
For more complete information about VLD-362 and VLD-362W object data, see
VLD Installation and Operations Guide (LTBT-MT-VLDIOG), available on the
ASN.
VAViH-SD Special BVs
Ta ble 67
VAViH-SD special BV objects
Point
DIP Switch
Remarks
BV-88
1
OFF= No Fan, Cooling
ON= Fan, Reheat
BV-89
2
OFF= Series Fan
ON= Parallel Fan
BV-90
3
OFF= Modulating Heat
ON= Staged Heat
BV-91
4
OFF= 1 Stage Heat
ON= 2 Stages Heat
BV-92
5
OFF= Heat On = Output On
ON= Heat On = Output Off
BV-93
6
OFF= Inactive
ON= Active
BV-94
7
OFF= Inactive
ON= Active
BV-95
8
OFF= Inactive
ON= Active
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Chapter 7 | Object and property reference
Note For information on reserved objects and other details about the VAViH-SD, see “Configuring the
VAViH-SD” in Gen4 VLCs Installations and Operations Guide (LTBT-TM-GEN4-IOG), available on the Alerton
Support Network (ASN).
Air balance data points
Air balance data are available as Present Value of reserved objects. In VAV-series VLCs, six new AVs provide read/
write access to airflow calibration data. This feature lets you place properties on a BACtalk display that can then be
printed to generate an air balance report. This reduces setup, calibration, and balancing time.
Im po rtant The objects listed below only have a present value property. No other properties are available.
*The Present Value of AV-250 and AV-253 are the only properties that can be read by the VLC DDC. Other objects
are not available in DDC.
Ta ble 68
Air balance data points
Object
Range
Meaning
AV-250a
0-63
Cold Deck box size, in inches
AV-251
0-102.3
Cold Deck velocity cutoff value, as a percentage
AV-252
10.23
Cold Deck calibration factor
AV-253a
0-63
Hot Deck box size, in inches
AV-254
0-102.3
Hot Deck velocity cutoff value, as a percentage
AV-255
0-10.23
Hot Deck calibration factor
a.The present value of AV-250 and AV-253 are the only properties that can be read by the VLC DDC. Other objects are not available in DDC.
VLC-444 reserved BVs
Ta ble 69
VLC-444 reserved BV objects
Point
Object name
Remarks
BV (300-303)
BV nnn
Read-only. “Active” indicates AO 0 to AO 3 have
detected current mode (load is 550 Ohms or less).
“Inactive” indicates voltage mode (load is 1K Ohm or
higher).
BV (400-403)
BV nnn
Enables the 4.22K pullup on AI 0 to AI 3 (with room for
AI 4 to AI 31). Gets set to default value from DDC
header at beginning of first DDC pass, allowing DDC to
override the default.
Advanced VLC objects (VLCA-1688 only)
This section describes objects that are unique to Advanced VLC devices.
© Honeywell
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Reserved AIs
Ta ble 70
Advanced VLC special AIs
Point
Remarks
AI-100
Number of times the unit has been powered up
AI-101
Number of times the controller has been reset externally (e.g. due to power failure)
AI-102
Number of times the controller has been reset due to the hardware watchdog.
AI-103
Number of times the controller has been reset due to executing an illegal opcode
AI-104
Number of times the controller has been reset due to accessing an invalid address
AI-105
Always zero
AI-106
Number of times the controller has reset for any reason
AI-107
Number of times the controller has reset due to an internal integrity check or software watchdog.
Reserved BVs
Ta ble 71
Advanced VLC 1688 reserved BV objects
Point
Object name
Remarks
BV (200-215)
BV nnn
Turn AI current/voltage/resistance modes ON or OFF.
BV (300-307)
BV nnn
Read-only. “Active” indicates AO 0 to AO 3 have
detected current mode (load is 550 Ohms or less).
“Inactive” indicates voltage mode (load is 1K ohm or
higher).
BV (400-415)
BV nnn
Enables the resistor on AI 0 to AI 3 (with room for AI 4 to
AI 31). Gets set to default value from DDC header at
beginning of first DDC pass, allowing DDC to override
the default.
AI mode control BVs
The VLCA-1688 features reserved BVs that control the mode in which the AIs operate. The BVs are numbered
BV-2nn and BV-4nn where nn represents the corresponding AI number. For example, BV-210 and BV-410 control
AI-10.
Ta ble 72
VLCA-1688 reserved BV
If the AI input type is:
and BV-2nn is set to:
and BV-4nn is set to:
the mode will be:
Resistive only
any
any
Resistive mode
Voltage only
any
any
0-10V mode or current mode
with external resistor
Universal without built-in
current resistor
any
Inactive
0-10V mode or current mode
with external resistor
Universal without built-in
current resistor
any
Active
Resistive mode
Universal with built-in current
resistor
Inactive
Inactive
0-10V mode or current mode
with external resistor
Universal with built-in current
resistor
Active
Inactive
Current mode using factory
calibration for built-in current
resistor
Universal with built-in current
resistor
any
Active
Resistive mode
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Reserved MVs
Ta ble 73
Miscellaneous reserved control BVs
Point
Remarks
MV-300-307
Show the current state of HOA switches for analog outputs
MV-350-357
Show the current state of HOA switches for binary outputs
Ta ble 74
MV switch positions
Switch position
MV value
Hand
1
Auto
3
Off
2
Properties of the Advanced VLC MV objects
Ta ble 75
Properties of the VLCA MV object
Property
W
Type
Example
Remarks
description

CharacterString
Operating
Status of AHU 1
An editable description of the object’s location or
function.
number-of-states
Unsigned
3
Indicates the number of states or selections to
which the MV can be set. The number-of-states is
defined only in the .bd6 DDC file.
object-identifier
BacnetObjectIdentifier
MV 1
This property consists of the object-type property
and the object instance, which is a numeric code
that identifies the object of interest.
CharacterString
AHU 1 Status
event-state
object-name

object-type
BACnetObjectType
(enumerated)
out-of-service
BOOLEAN
False
Always set to False.
unsigned
3
When EBT reads the present value it also reads
the state-text value associated with the present
value and displays both together to make it easier
to understand (for example, 3: Overridden).
state-text
BACnetArray[N] of
CharacterString
[1] Running
[2] Stopped
[3] Overridden
Defines the text associated with each state. This
provides a built-in way for the user to know what
each state represents.
status-flags
BACnetStatusFlags
(bitstring)
in alarm=0
fault=0
overridden=0
out of service=0
A four-position bit string that indicates the status of
the object. If a status bit =1, the status is TRUE.
present-value
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Properties of Advanced VLC Calendar objects
Ta ble 76
Properties of VLCA Calendar objects
Property
W
Type
Example
Remarks
date_list

List of
09/24/2009
Each entry can be an individual date, range of dates,
or month/week-of-month/day-of-week
BACnetCalendarEntry

description
object_identifier
BACnet_ Object_
Identifier

object_name
Character string
Character string
object_type
Enumerated
present_value
Enumerated
Default is “CAL n”
Properties of Advanced VLC Notification Class objects
Ta ble 77
Properties of VLCA Notification Class objects
Property
W
Type
Example
ack_required

BACnetEventTransti
onBits
description

Character string
notification_class
Unsigned
object_identifier
BACnet_ Object_
Identifier
object_name
Character string
object_type
Enumerated
Remarks
One bit for each event transition type - TOOFFNORMAL, TO-FAULT, and TO-NORMAL.
Indicates whether acknowledgement is required.
5
Equal to the instance of the object.
priority

BACnetArray[3] of
Unsigned
Priority to be used in event notifications for TOOFFNORMAL, TO-FAULT, and TO-NORMAL
event transitions. The range is 0-255. A lower
number indicates a higher priority
recipient_list

List of
BACnetDestination
List of recipients to receive notifications.
Properties of Advanced VLC Event Enrollment objects
Ta ble 78
Properties of VLC Event Enrollment objects
Property
W
Type
Example
Remarks
acked_transitions

bit string
To-offnormal
=1, To-fault
= 1, Tonormal = 1
Indicates whether the corresponding transitions have
been acknowledged. A 1 indicates that the transition was
acknowledged. Set in the Event Enrollment Editor at the
operator workstation.
description

Character string
event
enrollment 0
A description assigned to describe the object’s function.
event_enable

bit string
To-offnormal
=1, To-fault
= 1, Tonormal = 1
Indicates whether notifications are enabled for these
event transition types. A 1 indicates that the transition
will be reported. Set in the Event Enrollment Editor at the
operator workstation.
event_parameters
BACnetEvent
Parameter
change_of_
bitstring
event_state
Enumerated
NORMAL
214
Indicates the current state of the event.
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Ta ble 78
Properties of VLC Event Enrollment objects (Continued)
Property
W
Type
Example
Remarks

Enumerated
change_of_
bitstring
Indicates the type of event algorithm to be used to detect
events.
notification_class
Enumerated
1
Indicates the notification class to be used for event
transitions. Set in the Event Enrollment Editor at the
operator workstation.
notify_type
Unsigned
alarm
Indicates whether the object is set up for alarms or
events.
object_identifier
BACnet_ Object_
Identifier
Eventenrollment
0
This property consists of the object_type property and
the object instance, which is a numeric code that
identifies the object of interest.
object_name
Character string
Alarm
Assigned at the operator workstation.
Boolean
FALSE
Indicates whether the file has been saved for backup.
object_type
BACnetObjectType
eventenrollment
process_identifier
Unsigned
3
event_time_stamps
event_type
object_property_
reference

A numeric identifier for a handling process in the
recipient device. Set in the Event Enrollment Editor at
the operator workstation.
Properties of Advanced VLC Schedule objects
Ta ble 79
Properties of VLCA Schedule objects
Property
W
Type
Example
Remarks
description

Character string
Weekend Gym
A description assigned to describe the object’s
function.
effective_period

Sequence
<BACnet
DateRange>
Assigned in schedule setup at operator
workstation.
exception_schedule

Sequence
<Array of BACnet
Special
Event>
Assigned in schedule setup at operator
workstation.
list_of_object_
property_ references

List
<List of BACnet
Object
Property
Reference>
The list of objects that this schedule commands.
BACnet_ Object_
Identifier
schedule 0
This property consists of the object_type
property and the object instance, which is a
numeric code that identifies the object of interest.
Character string
schedule 000
Assigned in schedule setup at operator
workstation.
Enumerated
schedule
object_identifier
object_name

object_type
out_of_service
present_value

priority_for_writing

© Honeywell
Unsigned
FALSE
Always FALSE
ACTIVE
Indicates the value most recently written to a
referenced object property. May be analog,
binary, or other, depending on the controlled
property.
16
Assigned in schedule setup at operator
workstation.
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Ta ble 79
Properties of VLCA Schedule objects (Continued)
Property
W
reliability
schedule_default

status_flags
weekly_schedule

Type
Example
Remarks
BACnetReliability
no fault detected
Other possibilities are OVER RANGE, UNDER
RANGE, UNRELIABLE_OTHER.
Any
ACTIVE
Bit string
In alarm = 0, fault =
0, overridden = 0,
out of service = 0
A four-position bit string that indicates the status
of the object. If a status bit =1, that status is
TRUE.
Sequence
Array of
BACnetDailySchedu
le
Assigned in schedule setup at operator
workstation.
Properties of Advanced VLC Trendlog objects
Ta ble 80
Properties of VLCA Trendlog objects
Property
W
acked_transitions
Type
Example
Remarks
BACnetEventTransit
ionBits
Conveys flags that indicate the receipt of
acknowledgements for events.
buffer_size

Unsigned32
The maximum number of records the log file can
hold.
client_cov_increment

Double
The amount of change required to cause a log
record to be written. Only non-negative numbers
allowed.
cov_resubscription_int
erval

Integer
How often the trendlog resubscribes to the
monitored point. Units are seconds. Valid values
are 1 to 86,400 inclusive.
description

CharacterString
Description of the trendlog.
event_enable

BACnetEventTransit
ionBits
Enables or disables reporting of TO-FAULT and
TO-NORMAL events.
event_time_stamps
BACnetARRAY [3]
of
BACnetTimeStamp
The time an event occurred.
last_notify_record
Unsigned32
Sequence number of the log record that triggers
a notification.
log_buffer
BACnetLogMultiple
Record
A list of BACnetLogMultipleRecord records. Only
readable through ReadRange service
BACnetARRAY of
BACnetDeviceObjec
tPropertyReference
Specifies the properties to be logged. May
reference only internal objects.
event_state
log_device_object_pro
perty

log_enable

log_interval

Unsigned
The interval at which monitored properties are
logged. Set to zero for TRIGGERED
Logging_Type.
logging_type

BACnetLoggingTyp
e
Specifies whether records are collected by
polling or by triggered acquisition.
notification_class

Unsigned
The notification class used when handling event
notifications.
notification_threshold

Unsigned32
Specifies the number of records (since the last
notification) at which a notification is sent.
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Ta ble 80
Properties of VLCA Trendlog objects (Continued)
Property
W
Type
notify_type

BACnetNotifyType
Defines if notifications will be events or alarms.
BACnetObjectIdentif
ier
A numeric identifier for the associated object.
object_identifier
object_name

Example
Remarks
CharacterString
TLOG 14
The name of the trendlog object. Default is
“TLOG n”.
object_type
BACnetObjectType
TREND LOG
MULTIPLE
The object type of the trendlog.
record_count
Unsigned32
0
Represents the number of log records currently
in the Log_Buffer.
records_since_notificat
ion
Unsigned32
The number of log records since the last
notification.
start_time

BACnetDateTime
The date and time that logging will start.
stop_time

BACnetDateTime
The date and time that logging will stop.
stop_when_full

Boolean
Specifies whether logging should stop when the
log buffer is full. TRUE stops logging. FALSE
causes the oldest log records to be overwritten.
Unsigned32
Total number of log records collected by the
Trend Log Multiple object since creation. Wraps
total_record_count
back to 1 after reaching 232 - 1.
trigger
© Honeywell

Boolean
Causes the trendlog to log a record when the
value of the trigger property is changed from
FALSE to TRUE.
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8
Scaling factors
Input scaling refers to the conversion of an electrical signal from an input device to
some useful range, whatever that range is for your application: 0-100 %RH, 50-100
deg. F or 0-10 deg. C, -0.1 to 0.1 inches WC for static air pressure, and so on.
There are three key elements at work during this conversion: the electrical signal,
the raw counts, and the scaled input value.
Analog input signals to a VLC are fed into an analog-to-digital (A/D) converter in
the VLC. The A/D converts this into a binary number, which is the foundation for
the raw counts. This is necessary so the microprocessor and other components on
the VLC can interpret the signal. Software in the VLC then converts the raw counts
to a usable range, what you see in Envision for BACtalk as the present-value of an
analog input (AI).
When setting up inputs from the Analog Input Setup tab of the Device Settings
dialog box in VisualLogic, choose "Scaled (Two Point)" from the Type drop-down
menu. The Two Point Scale Setup dialog box opens, enabling you to enter two mA
or voltage values along with the desired AI values.
Select "5.12V w/jumper or switch" for all Gen4 VLCs that include an input jumper
or switch and select "5.12V no jumper or switch" for all Gen4 VLCs that do not
have an input jumper or switch. The input scaling utility automatically calculates
the correct values for zero and range.
The following Gen4 VLCs do not include an input jumper or switch:
VAV-SD
VAV-DD7
VLCA-1688
VAV-DD
VLC-660R
VLD-362
VAV-SD2A
VLC-16160
VLD-362W
VLC-651R
VAViH-SD
VAVi-SD
VLC-444
The following Gen4 VLCs have an input jumper or switch:
© Honeywell
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VLC-853
VLC-550
VLC-1600
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DDC header file setups in VLC DDC
9
Each VLC has a header file with information about the VLC’s configuration and
addressing. The header is part of the DDC program.
Whenever a DDC sequence is saved, downloaded, or read from a VLC,
information in the DDC header is packaged with it. The DDC header contains
information about DDC files on the operator workstation, as well as AI, AV, AO,
BO, and Microset Field Service mode configurations. You set up this information
through the DDC Header menu in VLC DDC.
 To view the DDC Header menu
1. Confirm the following:
•
The device instance of the VLC you want to work with is specified.
•
You have read the DDC from the VLC so you do not inadvertently
overwrite an existing setup.
2. From the VLC DDC Main menu, choose F2 DDC, and then choose F2
Edit DDC Header.
I MP O R TA N T When you edit a controller with a DDC editor, only programming
information is saved. Geometric information and comments are lost.
Program Information screen
Note Data in the Program Information screen also appears and can be edited in
the Disk Files Screen.
The Program Information screen (F1 Program Information from the DDC Header
menu) gives you data about the currently viewed DDC file. This file information
helps you identify the origin of the DDC file for troubleshooting. Use the mouse to
position the cursor in the field you want to change, press Enter, and then type the
settings you want according to the following guidelines.
Representative and Job The representative and job name under which the file
was saved on the operator workstation hard disk. You must have security to
modify, save, or send DDC files with a given representative and job name.
Program The file name (minus the file extension) of the DDC program when it
was saved to disk.
Revision A revision number for the DDC program, which is typically important
only for Alerton Standard DDC files. This revision number can also be used by any
DDC author to manage versions of custom DDC.
Display The display number associated with this DDC file.
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AI setup
The Analog Input Setup screen (F2 AI from the DDC Header menu) is where
you perform scaling options for AIs. Use this screen to designate the type of
scaling you want to use for an input or the type of thermistor connected to the
input.
Universal inputs on VLCs can be configured to accept a variety of input types.
You perform this configuration in the AI Setup screen of VLC DDC. Depending
on the application and VLC, the setup for an input probably includes the
configuration of DIP switches or jumpers on the VLC itself.
These setup factors affect the software count that results from a given electrical
input.
Setting the AI type and scaling factors In the Type field of the AI Setup
screen, you can select one of the following:
• Counts The raw count is used (infinitely great resistance, an open,
results in a count of 4095; no resistance, a short, results in a count of 0).
• Scaled The raw input count is affected by the value of zero and range
as indicated on-screen.
RawCount  Range
ScaledCount = Zero + ------------------------------------------------- 4096 
• 10K Thermistor or 3K Thermistor
converted to temperature.
Raw counts are automatically
Note See the VLC Installation and Operations Guide (LTBT-TM-GEN4VLC)
for more detailed information and input scaling tables. Guidelines for setting up
pulse-type inputs is also provided.
Keep the following in mind:
• The zero and range options apply only to scaled input types. No
additional scaling is required for 3K ohm and 10k ohm thermistor AIs.
• For any AI set up as a thermistor, the input is configured automatically
to degrees F or degrees C as appropriate for the selection of English or
Metric units.
• Use F10 to view setup parameters for additional inputs.
• The scaling options you select are saved with the DDC as part of the
DDC header.
Scaling example 1 A 0-10VDC pressure transducer with a range of 0”-4” water
column (WC) is used to measure duct static pressure. The value for range is
calculated as the value of AI with an input of 10VDC (input count = 4095) minus
the value of AI with an input of 0VDC (input count =0). Range = 4”. The value
for zero is the value of AI when the input is 0. Zero = 0”.
Scaling Example 2 A 4-20mA pressure transducer with a range of –0.25” to
0.25” WC is used to measure building pressure. The range is calculated as the
variation in AI as the input count goes from 800-4000 or 880-4000 depending on
the VLC type. See the VLCs Installation and Operations Guide (LTBT-TMGEN4VLC) for more information.
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In this example, however, the transducer output only goes down to 4mA, not
0mA. The challenge is to figure out what the pressure range would be if the
sensor output went all the way from 0mA to 20mA. Since the 16mA change
from 4mA to 20mA corresponds to pressure range of 0.5" (0.25" to -0.25"
=0.5"), a 20mA would theoretically correspond to a pressure range of 0.625"
(20/16 x 0.5). The value for range in this example is then equal to 0.625”. To
calculate and enter values for range, AI, and input at 20mA, 0.25” = zero + (4000
x 0.625)/4096. Zero is then equal to -.375”.
Using input filters VLCs use a 10-bit A/D converter, which is very responsive
to changes in electrical signals. This makes the inputs of the VLCs extremely
sensitive to minute changes, which may or may not be desirable.
You can turn filtering ON and OFF by placing the cursor in the Filter field for an
AI and pressing Enter to toggle the value.
The filter calculation is performed every 0.1 seconds and is expressed as:
NewCount 31
FilteredCount = --------------------------- + ------  PreviousCount
32
32
CAUTION Do not filter any Microset/Microtouch inputs.
English/Metric Mode setup VLCs support English or metric units. Once set up
from the AI Setup screen in the DDC header, the VLC makes all of its
calculations and writes to the Envision for BACtalk displays and Microset
display.
Having the unit of measure specified in the DDC header enables DDC programs
to individually accommodate different measurement systems.
 To toggle between English and metric mode
1. Choose F2 AI from the DDC Header menu.
2. Position the cursor in the English/Metric Mode field.
3. Press Enter to change the mode.
N o t e For VAV controllers, the setting of the English/Metric Mode
field determines whether airflow is reported in cfm or lps.
Units setup Units do not affect calculations. They are included for reference
only, and to populate the Units property for the AI. Position the cursor in the
field, press Enter, and type the numerical ID of the units you want to use. Before
you press Enter, press F4 to view a description of the current units. Press F5 to
view a list of all units and corresponding IDs.
AV setup
In the AV Setup screen (F3 AV from the DDC Header menu), you determine the
units property of all the AV objects present in the VLC. The units property has
no effect on the present-value of the AV. For most applications, it is unnecessary
to set up units unless you use the property on a display.
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Note You can also press Enter in the Units field and type the engineering unit
code directly.
 To set up the units property of an AV
1. From the VLC DDC main menu, choose F2 DDC, and then choose F2
Edit DDC Header from the DDC menu.
2. Choose F3-AV-Analog Values.
A list of AVs appears, each AV with a corresponding Units field. In the
Units field, the unit ID is listed.
3. Press F9 or F10 to view additional AVs.
4. Position the cursor in the Units field for the AV you want to configure.
5. Press F5 to view a list of engineering unit codes and descriptions.
6. Press F9 or F10 to view additional unit codes and descriptions.
7. Position the mouse pointer on the unit code you want to use and click
once.
On the AV Setup screen, the unit type you selected appears in the Units
field.
8. Repeat steps 4 thru 7 for each AV you want to configure.
BO setup
In the BO Setup screen (F4 BO from the DDC Header menu), you configure two
important features for each BO—the relinquish-default and the out-of-service
property. The relinquish-default and out-of-service properties relate to the
priority-array.
Relinquish default The relinquish-default is the value sent to the BO when
commands for every level of its priority-array are NULL—essentially, its normal
state when no command has been issued for the BO.
Options are ACTIVE (ON) and INACTIVE (OFF). Position the cursor in this
field for the BO you want to configure, and then press Enter to toggle between
ACTIVE and INACTIVE.
CAUTION Present–value continues to represent the result of the priority-array
index when out-of-service is set to TRUE.
Out-of-service The out-of-service flag determines whether the BO can be
commanded from an external device. If out-of-service is TRUE, only the
device’s internal DDC controls the status of the BO, and the BO is decoupled
from its priority-array. If out-of-service is FALSE, the BO can be commanded
from throughout the BACnet system and its status is determined by the priorityarray. Position the cursor in the Out of Service field for the BO you want to
configure, and then press Enter to toggle between TRUE and FALSE.
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AO setup
The AO Setup screen (F5 AO from the DDC Header menu) allows you to
configure the units, out-of-service property, and relinquish-default for AOs. The
relinquish-default and out-of-service properties relate to the priority-array.
Note Set the units property of the AO as you do for AVs. See “AV setup” on
page 223 for details.
Relinquish-default and out-of-service These have the same function as for
BOs. However, for the relinquish-default, you specify a number from 0–100.
Microset Field Service mode custom codes
VLCs enable you to set up custom field service codes for the Microset. Using
this feature, you can display and change the value of AI (read-only), BI (readonly), AV, BV, AO, and BO objects from the BACtalk Microset. You can set up
to 26 custom field service mode codes. While in Balance mode, a constricted
view of the custom codes is displayed. You can view/change only the first five
custom codes defined in VLC DDC. You can change the order of custom codes
in VisualLogic or VLC DDC.
In Field Service mode, a series of two-character codes correspond to each object.
You select the objects to be displayed and choose the codes that identify them
using the Microset Field Service Mode Setup screen (F6 Microset Field Service
Mode Control Table from the DDC Header menu).
Entry Identifies the entry and can’t be edited. In Field Service mode, entry 0
appears first, entry 25 appears last.
Display Code The two-digit code to be displayed at the Microset. Limited to
acceptable characters and must be two characters. Press F5 to view the list of
acceptable characters or use the following reference. Position the cursor in this
field, press Enter, and then type acceptable characters.
Ta ble 81
0
3
6
9a
c
E
h
J
o
u
-
Acceptable Microset Field Service mode characters
1
4
7
A
2
5
8
b
C
F
d
H
L
p
U
_
ga
i
n
r
y
a. The characters 9 and g are virtually indistinguishable on the Microset display.
Point ID Defines the VLC data point whose value is associated with the display
code. AI, BI, AO, BO, AV, and BV are acceptable point types. Position the
cursor in this field, press Enter, and then type an acceptable point type. Press
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Enter again and type the point’s instance (for AI 1, type 1, for example). Make
sure the point you reference actually exists in the VLC.
Writable Determines whether the value is writable from the Microset (YES) or
read only (NO). Position the cursor in the field and press Enter to toggle the
value. AIs and BIs are not writable.
Decimal Determines whether the Microset shows the value with a decimal
(YES) or without one (NO). Position the cursor in this field and press Enter to
toggle the value.
CAUTION The BACtalk Microset displays OFF values as 0 and ON values
as .1. You must set the Decimal field to YES to view or change binary values at
the Microset.
Non-negative Determines whether only positive values can be displayed (YES)
or negative values as well (NO). Position the cursor in this field and press Enter
to toggle the value.
Setting control flags
On the Control Flags screen (F7 - Control Flags from the DDC Header menu),
you can define the program units (English or Metric mode), make descriptors
writable, set auto-detection for Microsets, and make DDC unreadable.
Program Units Determines how the VLC interprets 10K ohm and 3K ohm
thermistor inputs as well as Microset- and Microtouch-related objects. For VAV
controllers, if program units are set to metric, enter box size in centimeters; the
device then reports flow in liters per second (lps).
 To set program units for a VLC
1. On the DDC Header menu screen, press F7.
2. In the English/Metric mode field, press the tab key to toggle between
English and Metric.
3. Press F8 when you finish.
Writable DDC/Descriptions With the creation of GEN4 VLCs, the description
properties of AI, AO, AV, BI, BO, and BV objects are writable using the
standard BACnet services. However, C3-series VLCs only allow the DDC
programmer to enter descriptions as part of the DDC file and not edit them from
a standard operator workstation.
The Writable/DDC Descriptions option allows the DDC programmer to select
whether to use the descriptions embedded in the DDC file or the writable
descriptions.
For more complete information see See “Writing object names and descriptions
to Gen4 devices” on page 100.
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Chapter 9 | DDC header file setups in VLC DDC
 To make VLC descriptions writable
1. On the DDC Header menu screen, press F7.
2. In the Writable DDC/Descriptions field, press TAB to toggle between
DDC and Writable.
3. Press F8.
Microset Auto-Detection VLCs detect Microsets connected to Input 0 by
default. However, this interferes when using dry contact inputs on Input 0.
Disable the Microset Auto-Detection feature to allow connection of a dry contact
input.
 To set up auto-detection of Microset controllers
1. On the DDC Header menu screen, press F7.
2. In the Microset Auto-Detection field, press the tab key to toggle
between Enabled and Disabled.
3. Press F8 when you finish.
DDC Read Inhibit Some users may want to protect the DDC file in the VLC.
You can do this by preventing reads of the DDC file.
CAUTION Be sure to back up your DDC file before setting this option. There
is no workaround to this protection once it has been set. You must download a
new DDC file.
 To prevent reads of the DDC file
1. On the DDC Header menu screen, press F7.
2. In the DDC Read Inhibit field, press the tab key to toggle between
Reads Allowed and Reads Inhibited.
3. Press F8 when you finish.
Setting parameters for a VAV airflow sensor
VAV controllers have a special screen in the VLC DDC program for setting up
airflow sensor parameters. In this configuration screen, you specify a box size, a
calibration factor, the point below which airflow should read zero (zero cutoff),
and the values of AI-8 and AI-10 (for dual duct VLCs), or AI-10 (for single duct
VLCs).
Note You can also adjust the values for the hot duct and cold duct calibration
factors from the BACtalk Microset using the Microset Airflow Calibration
mode.
This is a one-time setup you perform for each VAV VLC; the setup is stored in
the VLC independently of DDC or header information. This configuration
affects the values that represent airflow for VAV VLCs.
Note The program units setting (English or metric) in the Analog Input Setup
screen (see “AI setup” on page 222) determines whether AIs report airflow in
cfm or lps, and whether temperatures are reported in degrees F or C.
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 To set up airflow parameters for a VAV VLC
1. Make sure you select the Device ID of the VLC you want to work with
in the Configuration screen. Also, choose F2 Read File to retrieve the
existing setup data from the VLC so you do not inadvertently overwrite
an existing setup.
2. From the VLC DDC Main menu, choose F1 Configure.
3. From the Configuration menu, choose F3 VAV Flow Sensor.
The VAV Flow Sensor Setup screen appears with fields for entering a
box size, calibration factor, and velocity zero cutoff for both the cold
duct and the hot duct. For single-duct VAV controllers (SD), only the
cold duct information is used.
4. Position the cursor in the field you want to edit, press Enter, and then set
parameters according to the following guidelines.
Box diameter The box diameter of the VAV box to be controlled by this VLC.
Enter this value in inches or centimeters as appropriate for English or metric
setup in the AI Setup screen (see “AI setup” on page 222). Obtain box diameter
data from the VAV box manufacturer. The box diameter represents the round
duct equivalent diameter of the duct where the pressure pickup is located.
Calibration factor Adjusts the VLC airflow readings to match the specific VAV
box, airflow pickup, and conditions of an installation. Increasing the value of the
calibration factor increases the value of the corresponding airflow (AI-8 for hot
duct flow, if applicable; AI-10 for cold duct flow).
The calibration factor for each duct should be adjusted until the corresponding
airflow matches the airflow measured using a balancing hood. The default value
for the calibration factor, 1.00, accounts for no pressure loss in the tubes.
Increase the calibration factor to compensate for tube loss.
Velocity zero cutoff This value is entered in percent of full airflow (0-100).
Airflows lower than the cutoff are reported as zero. This feature eliminates
nonzero airflow readings because of ambient fluctuations when the main fan is
off.
 To send data to the VLC
When you finish, press F1 to send the VAV airflow setup information to the
VLC.
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