ICS Regent+Plus
®
PD-7011
DC Digital Input Modules
24 VDC, 48 VDC and 120 VDC
(T7401, T7402 and T7408)
Issue 1, March, 06
DC digital input modules provide input sensing for 16 field
input switches. Three types of modules are available for
interfacing to inputs powered from 24, 48, or 120 VDC field
power supplies. Each module's triplicated I/O Safetybus
interface ensures that no failure in the module can affect the
operation of the Regent system or other I/O modules in the
system. Extensive fault detection and annunciation of critical
redundant circuits help prevent the controllers from receiving
erroneous data from a faulty input module.
Features
·
Sixteen input circuits, configured as two isolated groups of
eight circuits each.
·
Fault tolerant operation when connected in parallel with
redundant modules of the same type.
·
Hot-replaceable.
·
Automatic self-testing of triplicated I/O Safetybus circuits and
many simplex logic circuits.
·
Individual front panel indicators on each module show active
and fault status and logic-side input on/off status.
·
2500 volt minimum electrical isolation between field and logic
circuits.
·
TÜV certified, Risk Class 5.
Three DC digital input modules can be connected in parallel
to obtain fault tolerant input sensing. In this triple module
configuration, a failed module can be removed and replaced
without interrupting the input signals.
Industrial Control Services
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DC Digital Input Modules (T7401, 02, and 08)
Module Operation
A block diagram of a typical DC digital input module is shown
in Figure 1.
Optical isolation between field wiring and the modules’ logic
circuitry provides field-to-logic isolation — protecting the
modules’ logic circuits from field signal over-voltages,
transients, and other electrical disturbances. It also provides
a safety barrier between the primary field voltages and user
accessible circuits.
Figure 1. Block Diagram of DC Digital Input Module.
When the field switch is closed, the input to the module is on.
When the field switch opens, the input to the module turns off.
Data from the logic side of the optical isolators are bused to
the I/O bus interface logic.
The processor modules send triplicated read data requests to
the input module over the I/O Safetybus. The processors’
addressing data and data read requests are voted by the
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(T7401, 02, and 08) DC Digital Input Modules
module (preventing I/O Safetybus failures upstream from the
module from affecting its ability to be read). The voted result
is then passed to the I/O bus interface logic.
After receiving the voted data read request, the I/O bus
interface logic sends its input data to the module’s three bus
drivers. Each of the three bus drivers is independently
powered and controlled by the I/O transceiver modules—
preventing failures in a single driver from propagating to the
other two busses.
The bus drivers transmit the data across the backplane I/O
Safetybus to the I/O transceivers which, in turn, transmit the
data to the processors.
Testing and Diagnostics
Each module’s voter circuits are periodically tested by the
processor modules. Discrepant data are sent through one of
three legs of the I/O Safetybus to determine whether the
module’s voter is able to outvote the incorrect data. A failure
to return the correct majority-voted result to the processors
produces an I/O module error indication at the processor
modules and a module fault indication at the I/O module.
Each type of module has a unique identification code that is
read by the controller. This code lets the controller know
which type of module is installed in each I/O chassis slot and
how to address that module and its points specifically. If a
module is removed, or is replaced with a module of a different
type, the processor modules will indicate I/O module errors.
Loopback logic tests periodically write data to the module and
then read it back to determine whether the module’s I/O bus
interface logic is functioning correctly.
Front Panel Indicators
Figure 2 shows the physical features of the DC digital input
modules. The front panel of each module contains active and
fault status indicators and field signal status indicators for
each circuit.
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DC Digital Input Modules (T7401, 02, and 08)
Figure 2. DC Digital Input Module.
Active and Fault Status Indicators
These green and red LEDs indicate the overall health of the
module. During normal operation the green ACTIVE
indicator flashes at the controller's scan rate. If a module
fault is detected the red FAULT indicator turns on and the
green indicator turns off.
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Industrial Control Services
(T7401, 02, and 08) DC Digital Input Modules
Field Status Indicators
Input status indicators are located on the logic-side (after the
signal conditioning and isolation). The field status indicators
are lit when current is flowing through the input.
Application
Simplex Configuration
Digital input modules provide a suitable interface to noncritical input signals. Although many of the circuits in the
digital input modules are automatically tested and
annunciated, some logic circuits and all of the field-side
sensing circuits are simplex and non-tested. This simplex
input configuration is illustrated in Figure 3.
Figure 3. Simplex Digital Input Configuration.
Fault Tolerant Connection
For critical inputs, redundant input modules are used in a
2oo3 or 1oo2 fault tolerant configuration. In these
configurations the redundant input modules are connected to
single or multiple sensors. If redundant sensors are installed
in the field, the redundant modules are connected so that each
sensor connects to one of the redundant modules. These
configurations are illustrated in Figure 4, showing triple
redundant input modules. Each DC digital input module is
hot replaceable. In triple redundant input configurations, if a
fault occurs on one module, it can be removed and replaced
PD-7011
Mar-06
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DC Digital Input Modules (T7401, 02, and 08)
while the system continues to sense the inputs from the
remaining two input modules.
Figure 4. Fault Tolerant Digital Input Configurations.
Field Wiring
For field wiring details, refer to PD-7901 - I/O Termination
Assembly (ITA).
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Industrial Control Services
(T7401, 02, and 08) DC Digital Input Modules
Keying
The I/O chassis can be physically keyed to prevent accidental
damage caused by inserting a module into a slot wired for a
different module type. Figure 5 illustrates how the slot keys
are installed on the I/O chassis slot field wiring connectors.
The slot key positions for the DC digital input modules are
listed in Table 1.
Figure 5. Installing Slot Keys.
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Mar-06
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DC Digital Input Modules (T7401, 02, and 08)
Table 1. Slot Key Positions.
Module
Upper
Connector
Lower
Connector
T7401
4
15
T7402
10
15
T7408
12
15
Configuration
Each input module is configured using the WINTERPRET I/O
Configuration Editor. In the editor, you will perform the
three steps described below to configure the input module.
1) Set the Module Type:
Position the cursor on the module slot you wish to define.
Choose Set Module Type from the Edit Menu and select
the appropriate digital input module from the list.
2) Edit the Module Definition:
Choose Edit Module Definition from the Edit Menu. A
dialog box will open where you can define the input point
definitions.
Figure 6. Digital Input Module Definition.
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Industrial Control Services
(T7401, 02, and 08) DC Digital Input Modules
3) Edit each point:
Choose Edit from the Module Definition dialog box to
define a name and description for each I/O point. In the
Digital Input Point dialog, enter a tag name (up to 12
characters) and a description (up to 40 characters).
Figure 7. Defining a Digital Input Point.
The tag names are used in the application program to
represent the input state. In addition, a module tag name can
be entered to represent the combined state of all 16 inputs.
This module tag name represents the 16 inputs as a signed,
16-bit integer. In this format, input point one is the least
significant bit (LSB) and input point 16 is the most significant
bit (MSB).
Programming
Inputs are referenced in the application program through the
tag names defined in the I/O Configuration Editor. When
current flows through the input (field switch closed) the input
is said to be on, or have a value of one. In ladder logic, the on
state would produce power flow in a normally open (N.O.)
contact.
To program fault tolerant configurations using triplicated
digital input modules, a voter element can be used as shown
in Figure 8.
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DC Digital Input Modules (T7401, 02, and 08)
Figure 8. Programming Fault Tolerant Digital Inputs.
In this illustration, VOTE_A_NAME, VOTE_B_NAME, and
VOTE_C_NAME represent the three digital inputs to be twoout-of-three voted. ERROR_A_NAME, ERROR_B_NAME
and ERROR_C_NAME are the error bits for the digital
inputs. RESULT_NAME is the result of the voter instruction.
The field Msec is the time, in milliseconds, an input can be
incorrect before signaling an error. RESET_NAME is the
reset bit used to reset the latched error bits.
The voter instruction can be used to vote digital input points
or entire digital input modules. When voting digital input
modules, the tag names VOTE_A_NAME, VOTE_B_NAME,
and VOTE_C_NAME would be the names of the digital input
modules and RESULT_NAME would be a shared variable
register. After voting the modules, a block move instruction
should be used to move the contents of the register
RESULT_NAME into individual shared variable control
relays. Refer to the WINTERPRET Help files for more
information about the block move instruction and shared
variable definitions.
Maintenance
No periodic maintenance or calibration is required for the
digital input modules. There are no user replaceable parts
inside these modules. In safety critical input applications, the
inputs should be dynamically transitioned at a period not
greater than six months.
Safety Considerations
The DC voltage digital input modules are TÜV certified as
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Industrial Control Services
(T7401, 02, and 08) DC Digital Input Modules
non-interfering and when properly configured are also
certified for Risk Class 5 safety critical inputs. Safety critical
configurations include 2oo3 and 1oo2 voting methods.
In safety critical input applications using a single sensor, it is
important that the sensor failure modes be predictable and
well understood, so there is little probability of a failed sensor
not responding to a critical process condition. In such a
configuration, it is important that the sensor be tested
regularly, either by dynamic process conditions that are
verified in the Regent, or by manual intervention testing.
Redundant sensors can be used with redundant input
modules to eliminate any single points of failure and extend
fault tolerance to include the sensors.
In all safety critical configurations and applications, the DC
voltage digital input modules can be used for de-energized to
trip inputs, only if the inputs are dynamically transitioned at
a period not greater than six months.
For additional safety considerations, please refer to the Safety
Considerations section of the Regent User’s Guide.
PD-7011
Mar-06
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DC Digital Input Modules (T7401, 02, and 08)
Specifications
Safetybus Power
1.15 load units
Number of Inputs
16 circuits divided into two
groups of eight
Voltage Range
Turn-On Voltage
Turn-Off Voltage
Input Current
Turn-On Delay
minimum
maximum
T7401
T7402
T7408
14 to 30 VDC
38 to 58 VDC
95 to 150 VDC
12 VDC, min
36 VDC, min
88 VDC, min
4.7 VDC, max
11 VDC, max
28 VDC, max
8.7 mA
4.4 mA
4.4 mA
0.2 msec
0.1 msec
0.05 msec
1.8 msec
1.0 msec
0.4 msec
0.5 msec
0.15 msec
0.05 msec
2.6 msec
1.0 msec
0.5 msec
50 VAC
140 VAC
400 VAC
80 VAC, for
5 sec
220 VAC, for 5
sec
880 VAC, for
5 sec
10 Watts,
9.5 Watts,
18 Watts,
34 BTUs/hour
32 BTUs/hour
60 BTUs/hour
Turn-Off Delay
minimum
maximum
Over Voltage
Protection
continuous:
burst:
Heat
Dissipation
Fusing
Isolation
12
None, fuse external if
required
2500 volts minimum (field
wiring to control logic)
2500 volts minimum (input
group 1-8 to input group
9-16)
Operating Temperature
0° to 60° C
(32° to 140° F)
Storage Temperature
-40° to 85° C
(-40° to 185° F)
Industrial Control Services
(T7401, 02, and 08) DC Digital Input Modules
Operating Humidity
0 to 95% relative humidity,
non-condensing
Vibration
10 to 55 Hz:
±0.15mm
Shock
Operating:
15 g, ½ sine wave, 11 msec
Electromagnetic
Interference
•
•
•
IEC 801 Part 2 - Electrostatic
Discharges
IEC 801 Part 3 - Radiated
Electromagnetic Fields
ANSI/IEEE C37.90 - Surge
Withstand Capability
Safety
Level 3: Contact discharge of
6 kV
Level 3: 10 V/M, 27 MHz 500 MHz
2.5 kV damped 1 MHz sine
wave
4 kV bi-directional impulse,
10 nsec rise time, fast
transient (T3402, T3408 only)
Certified to DIN V VDE
0801 for Risk Class 5. Also
designed to meet UL 508 and
CSA 22.2, No. 142-M1981
Dimensions
Height:
Width:
Depth:
Weight
PD-7011
Mar-06
12.6" (320 mm)
1.27" (32 mm)
10.12" (257 mm)
3.0 lbs (1.4 kg)
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