Omega CN491A Owner Manual

Contents
1.0 Introduction.............................................. 3
2.0 Installation..............................................
2.1 System Requirements.....................................
2.2 Installation of CN491A-SOFT.............................
2.3 Communications Setup....................................
4
4
4
5
3.0 CN491A-SOFT Operation..................................... 7
3.1 Start-up................................................ 7
3.1.1 Initial Set-up of CN491A-SOFT ....................... 7
3.1.2 Com Port and Database Selection ..................... 8
3.1.3 Address Selection ................................... 9
3.2 CN491A-SOFT Graphical Interface........................ 10
3.2.1 Trend Display/ Trend Printing ...................... 11
3.2.2 Bar Display ........................................ 12
3.2.3 PV Display, DevHi/DevLo Alarm and Database Control . 13
3.2.4 Communication Status Display ....................... 14
3.3 Communication and Parameters Table..................... 15
3.3.1 Polling Parameters................................... 15
3.3.2 Modifying Parameters ............................... 16
3.3.4 Saving the Updated Parameters to Database .......... 17
3.4 Modifying All Addresses, Modifying Single Address and
DevHi/Lo Settings...................................... 17
3.4.1 Modifying Parameters to All Addresses .............. 18
3.4.2 Modifying Parameters to a Single Address ........... 18
3.4.3 Changing the DevHi/DevLo Settings .................. 19
3.5 Main Menu Operation.................................... 19
3.5.1 Export Data ........................................ 19
3.5.2 Export Parameters .................................. 20
3.5.3 RS485 Communication and Parameters Table ........... 20
3.5.4 ModifyAll .......................................... 20
3.5.5 Minimize ........................................... 21
3.5.6 DevHi/DevLo Setting ................................ 21
3.5.7 Data Backup ........................................ 21
3.5.8 Reset Database ..................................... 21
3.5.9 Exiting ............................................ 22
4.0 Database of CN491A-SOFT.................................. 23
5.0 Protocol.................................................
5.1 ASCII Framing..........................................
5.1.1 Address Field ......................................
5.1.2 Command Field ......................................
5.1.3 Parameter Field ....................................
5.1.4 Data Field .........................................
5.1.5 Checksum Protocol ..................................
5.2 Command Summary........................................
5.2.1 Poll a Parameter from the Assigned Address .........
5.2.2 Modify a Parameter to the Assigned Address .........
1
24
24
24
24
25
25
25
27
27
27
6.0 Command, Parameter and Data Codes Tables................. 29
6.1 Command Codes Table.................................... 29
6.2 Parameter and Data Codes Table......................... 30
7.0 Programming Examples..................................... 33
8.0 DDE to other Applications............................... 35
8.1 DDE Demo............................................... 36
9.0 Appendix.................................................
Appendix A.................................................
Appendix B.................................................
Appendix C.................................................
39
39
40
41
Notes........................................................ 42
2
1.0 Introduction
The Omega Engineering CN491A controllers use serial, halfduplex communication mode with multi-drop link to exchange
information.
The CN491A-SOFT is a Windows-based software that allows an
operator to completely configure and monitor up to 31 CN491A
controllers with communications option, via a 2-wire EIA-485
serial communications line. It works on systems running Windows
NT, Windows95, or later versions. The controllers will be
polled one at a time and are identified by their station
numbers. The main display window includes a real-time trend
display, a bar graph and a table with the current process values
of all the stations. The trend display can be assigned up to six
stations at a time. This lets the user observe the behavior of
six different processes in six different colors. The bar display
lets the user observe the variations of process value, setpoint,
and the amount of output from the controller. The display could
be set for a specific station or to scan all the stations
sequentially. The historical process database and the parameter
data can be exported to a file and analyzed by other application
programs.
3
2.0 Installation
The installation procedure provides the necessary steps
required to directly link up to 31 controllers (remote units) to
the host computer (master).
2.1 System Requirements
a. CN491A controller with RS485 communications
(C4 option). Example: CN491A-R1-R2-C4
b. RS-485 to RS-232 converter.
Example: Omega Part No. CAT-285
c. Host computer
RAM: 16MB
Hard Disk: 20MB free space
CD-ROM drive
SVGA: 800x600 resolution, 256 colors.
Operating System: Windows95, WindowsNT, or later.
d. Application Software: CN491A-SOFT
2.2 Installation of CN491A-SOFT
„ The host computer should be running Windows 95 or a later
version.
„ Insert the CD-ROM provided with the controller. Open
folder “Disk 1” and click on “Setup.exe”
„ The “CN491A-SOFT Setup” dialog box will be displayed.
Click “change directory” button if necessary.
„ Create a new directory, C:\CN491A-SOFT (for example),if
necessary, then click the “OK” button.
„ Click the installation icon to install the CN491A-SOFT
application to the specified destination directory.
„ After finishing the CN491A-SOFT setup, you can start the
program by clicking on the CN491A-SOFT icon in the program
menu.
4
2.3 Communications Setup
a. Connect the controller and the computer
Remove power from both the controller and the computer
before connecting them together.
The RS485 communications uses a two-wire, half-duplex system.
You can have up to thirty-one controllers (remote units)
connected to a host computer (master) via a multi-drop link as
shown below.
tx1
tx2
tx1
tx2
Controller #1
RS-485
RS485 to RS232 Converter
tx1
RS-232
tx2
Controller #2
Computer’s Serial Port
Controller #31
Figure 2.1 RS485 interface wiring diagram when an external
converter is used
5
b. Set up the remote address from the controller’s
front panel
6
3.0 CN491A-SOFT Operation
Features of CN491A-SOFT:
„ Up to 31 controllers can be connected simultaneously.
A built-in database lets users access and manage both
the parameters and historical process data. It works
like a data logger.
„ CN491A-SOFT could function like a 6-channel recorder. A
trend display lets the user observe the dynamic
behaviour of up to six processes (addresses). The image
of the trend display can be printed out to a system or
network printer.
„ A bar display lets users monitor the Process Value
(PV), Set Value (SV), percent of output, or,
manipulated variable (MV), data for a specific
controller. This bar display can also be set to scan
all the stations in a fixed time interval
automatically.
„ User programmable DevHi/DevLo alarm and display for
monitoring real-time process values.
„ A data grid control handles the data communication of
polling/modifying parameters from/to all assigned
addresses, and also performs the function of updating
parameters automatically.
„ The historical process database (PV) and the parameter
data can be exported out to a file and analyzed by
other applications.
„ CN491A-SOFT is a built-in DDE (Dynamic Data Exchange)
source application. You can develop your own
application to take the data through the DDE mechanism.
3.1 Start-up
3.1.1 Initial Set-up of CN491A-SOFT
You can run CN491A-SOFT by clicking the item CN491A-SOFT in
the Windows program files list, and the Initial Setup window
will appear.
7
3.1.2 Com Port and Database Selection
Figure 3.1 The Initial Setup window
ƒ Select COM1, COM2, COM3, or COM4 as the serial Com Port
ƒ Select
Whenever
directly
software
the database file pv_database.mdb.
the program is started, the database path is
pointed to the directory you have created during
installation.
ƒ Click “OK” Button to finish the set-up of Com Port and
Database. The Address Selection window will open.
ƒ If you have to exit, Click “Exit” to stop execution of
the program. Some error messages will be displayed if
incorrect port or database path is specified.
ƒ There are two options for Comm Settings, “9600,N,8,1” or
“9600,N,7,2”. The default setting is “9600,N,8,1”
“9600,N,8,1”= 9600 Baud, No Parity,8 Data bits,1 Stop bit.
8
3.1.3 Address Selection
Figure 3.2
Address Selection window
ƒ Click on icons “A01….A31” to enable/disable the
addresses, and make sure the assigned addresses have the
corresponding controllers with the same value for the
parameter “Addr”. Make sure that no two controllers are
assigned the same address number.
ƒ Click “OK” to finish all the set-ups. The CN491A-SOFT
graphical interface and RS485 Communication and Parameter
Table windows will be opened, and the program begins
operating.
ƒ During Initial Setup, it fetches the old selected
address stored in the database and displays in the Address
Selection window, and once you click the “OK”, it updates
the new assigned Com Port, Com Settings and addresses into
the database as new default settings.
9
3.2 CN491A-SOFT Graphical Interface
Figure 3.3
CN491A-SOFT Graphical Interface
Functional Descriptions: (from top to bottom, left to
right)
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
Main Menu
Trend Display
PV Display and Database Control
Bar Display
RS485 Communication and Parameters Table
Communication Status
10
3.2.1 Trend Display/ Trend Printing
Figure 3.3.1
Trend Display
ƒ There are up to 6 trends that can be selected in trend
display. You can click on the “Address Displayed” frame
members to add or remove trends assigned to the selected
addresses. A different color for each trend helps you
distinguish them.
ƒ There is a text-box in the upper-left corner of trend
display. You can enter a 6-character title name that
will be saved in the database and shows in print-outs.
ƒ In the “StopRanging” mode, you can click “+”,”-“ button
in the “TrendScale” frame by altering the ScaleHi and
ScaleLo with 50 Counts/Click or 10 Counts/Click.
ƒ In the “AutoRanging” mode, the ScaleHi and ScaleLo will
be changed to their appropriate value automatically.
ƒ Check or uncheck the AutoRanging/StopRanging checkbox to
select AutoRanging or StopRanging alternately.
ƒ Click the “+”, “-“ button in the “Intvl” frame to change
the trend display interval. The interval unit is
secs/tick.
ƒ Click the Print button to print the trend display by the
system printer.
ƒ Check or uncheck the ColorPrinter/MonoPrinter checkbox if
using a color or monochrome printer.
ƒ The trend display can also be printed out periodically,
if the Auto/Manual checkbox is set on Auto mode.
11
3.2.2 Bar Display
Figure 3.3.2
Bar Display Window
ƒ The Bar display uses different colors for the Process
Variable (PV), Setpoint Value (SV), Manipulated Variable
(MV1 for output1, and MV2 for output2). Manipulated
variable is the amount of control output that the
controller delivers to the load.
ƒ There are 2 modes for the Bar display: “AutoScan”, and
“StopScan”. Check or uncheck “AutoScan/StopScan” checkbox
in the “Address” frame to switch between these two modes.
ƒ In “AutoScan” mode, the bar display will scan all
stations periodically.
ƒ In “StopScan” mode, the Bar display will scan a
particular station. You can select the station to be
displayed by clicking the “>|” or “|<” button in “Address”
frame.
ƒ Click the “+”, “-“ button in the “BarScale” frame to
change the high and low scale of the bar display.
ƒ Clicking the “Refresh” button will force the main program
to update the active bar display.
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3.2.3 PV Display, DevHi/DevLo Alarm and Database
Control
Figure 3.3.3 PV and Database Control
ƒ Real-time process values (PV) are displayed in the “A01”
to “A31” text box of the PV_PARA DataBase frame. Note that
the process values are always displayed to one decimal
place.
ƒ Different background color for each cell, from A01 to
A31, indicates whether the corresponding process variable
is inside the DevHi/DevLo limit or not.
Red background color: PV > (DevHi+SV)
Black background color : (SV-DevLo) < PV < (DevHi+SV)
Green background color: PV < (SV-DevLo).
Note: The parameters DevHi/DevLo-Deviation High/Deviation Low
are tools used only on the graphical interface on the PC,
independent of the parameters dvhi/dvLo used on the controllers.
ƒ You can change the value of DevHi/DevLo in run time as
described in section 3.4.3.
ƒ Check/uncheck the DevHiAlarmOn/DevHiAlarmOff checkbox to
enable/disable the DevHiAlarm.
ƒ Check/uncheck the DevLoAlarmOn/DevLoAlarmOff checkbox to
enable/disable the DevHiAlarm/DevLoAlarm
ƒ The database name, called pv_database.mdb which is
created by the Data Manager of Visual Basic, is an Access
database that is directly linked with the data control
designed in the PV_PARA Database frame. You can open it in
13
real time by Datman32.exe attached in the path created by
set-up, and refresh and view the historical records in the
database, but do not edit it directly. See Appendix A.
ƒ The database update interval, which indicates the time
period for updating the database table “PVS1” (historical
records of the process value), is 60 seconds for default
setting. Click the “+”/”-“ button to change the database
update interval.
3.2.4 Communication Status Display
Figure 3.3.4 Communication Status Display
ƒ The “RX” text records the number of response messages the
assigned remote controllers send back to the host computer.
ƒ The “Err” text records the number of incorrect Checksum
responses.
ƒ The “TX” text and “RX” text boxes indicate the Transmit
and Receive data exchange.
ƒ Click “Reset” button to reset all the above statistics.
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3.3 Communication and Parameters Table
Figure 3.4: Communication and Parameters Table
ƒ The parameter table is designed by the grid control,
which serves as a mechanism to display data in a tabular
format. However, unlike a spreadsheet, you cannot type data
inside the cell directly. Reading/writing data from/to a
cell is controlled by the source code.
ƒ The columns show the addresses “A01” to ”A31”, and the
rows show the data for the parameters.
ƒ The values of the parameters are fetched from the
database that was pointed to during start-up.
3.3.1 Polling Parameters
ƒ Click the relative cell position on the parameters table
to select the target address and the parameter, and the
corresponding “ADD” and “PARA” in “TX Framing” frame will
be changed with the new selection.
ƒ Click the “poll” button to read parameter from the
selected remote controller, the corresponding
“CMD:65(POLL)” in the “TX Framing” frame will be displayed
to reflect this selection.
ƒ After you have selected the “ADD”, “POLL”, and “PARA”,
click the telephone icon to send the data in TX Framing to
the communication port.
ƒ The received result will be displayed in the “Response”
15
text,and updated in the corresponding cell of the
parameters table.
3.3.2 Modifying Parameters
ƒ Click the relative cell position on the Parameters table
to select the target address and parameter, and the
corresponding “ADD” and “PARA” in the “TX Framing” frame
will be changed with the new selection.
ƒ Click the “Modify” button to write parameters to the
selected controller. The corresponding “CMD:66(Modify)” in
the “TX Framing” frame will be displayed to reflect this
selection.
ƒ Enter the desired data in the “DATA” text of the “TX
Framing” frame.
ƒ After you have selected the “ADD”, “MODIFY”, “PARA” and
“DATA”, click the telephone icon to send the text frame
“ADD, Modify, PARA, DATA” to the communication port.
ƒ The Receive result will be displayed in the “Response”
text, and updated in the corresponding cell of the
parameter table.
3.3.3 Updating Parameters Automatically
If, for some reason, the parameters of the remote controllers
get changed, CN491A-SOFT can detect the change.
There is a timer interrupt designed in the program. Once the
timer interrupt is enabled, it forces the main program to
service the “Polling parameters” subroutine immediately, that
will poll the parameter for that interrupt, and then poll all
the other parameters. So the parameters table always keeps the
newly updated parameters.
You may click on any cell in the parameter table to disable
the timer interrupt, and click on the telephone to alternately
enable it.
Please review the steps of Polling/Modifying parameters in
section 3.3.1 and 3.3.2. The timer interrupt is disabled at the
instant you click a cell in the parameters table, and is enabled
at the instant you click the telephone icon.
16
3.3.4 Saving the Updated Parameters to Database
Click the “SaveParaS” button to save the updated parameters
to the database that was pointed to in the Initial Setup window,
in section 3.1.2. This means that you must decide when to do
“SavePara” function, otherwise, the database will always keep
the old parameters.
3.4 Modifying All Addresses, Modifying Single
Address and DevHi/Lo Settings
ƒ When CN491A-SOFT is launched, it fetches the parameters
from the database that was pointed to in the Initial Setup
window, and then fills the parameters in the cells of the
grid table.
ƒ Unlike the grid table in section 3.3, the parameters in
the grid table are not updated in run-time. It just keeps
the initial (default) parameters for later use.
ƒ You can open a different database file that refers to a
different process, during start-up and then do ModifyAll to
replace all parameters with the new settings.
Figure 3.5: Modify All Parameters
17
3.4.1 Modifying Parameters to All Addresses
ƒ To change a parameter, click the relative cell in the
grid. The ”Data” text will display its value. Enter the
desired data in the “Data” text, and the new data will be
displayed in the relative cell.
ƒ Click the “ModifyAll” button to
write all the parameters in the
grid to the corresponding remote
controller.
ƒ ModifyAll is used only if
changing all parameters is needed
at the initial state. Please make
sure that all parameters are right
before you proceed to do
Modifyall.
ƒ After clicking ModifyAll button,
a warning frame will be displayed, and you can click “Ok”
button to continue, or click “Cancel” button if you decide
to exit ModifyAll operation.
3.4.2 Modifying Parameters to a Single Address
ƒ Click a grid cell which corresponds to an address of the
parameter you are going to modify.
ƒ Click the ModifySingle button (on the bottom-right of
Figure 3.5) to write parameters to the selected address.
ƒ Click Cancel button to exit.
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3.4.3 Changing the DevHi/DevLo Settings
Figure 3.6: Deviation Hi/Lo Settings
ƒ Click View/ DevHi/DevLo setting on the menu, and the
Deviation Setting window will be displayed.
ƒ To change a DevHi/DevLo
cell in the grid, and the
Enter the desired data in
fill in the corresponding
setting, click the corresponding
data box will display its value.
the box, and the new data will
cell.
ƒ After Changing the DevHi/DevLo setting, you must click
the SaveDevSetting button to save the new setting to
database.
ƒ To find out how it works, go to section 3.2.3
3.5 Main Menu Operation
3.5.1 Export Data
ƒ Click File/Export Data to export data. A file-export
dialog box will be displayed.
ƒ Specify a filename and the path the data file needs to be
exported.
ƒ The exported data file can easily be processed by any
text editor or imported to spreadsheets like Microsoft™
Excel.
19
3.5.2 Export Parameters
ƒ You can use the “Export Parameters” function to export
the parameters saved in the database table to any specified
file.
ƒ Click the File/ExportParameters in the “File” menu to
export parameters. A dialog box will be displayed asking
you whether to export parameters or not.
ƒ Click “Yes” button, and a “File Save” dialog box will be
displayed to let you specify the path of the file that you
want the parameters exported to.
ƒ The exported file is a simple text file, every field of a
record will be separated by comma, and every record will be
separated by CR and LF. So it can easily be processed by
any text editor or exported to spreadsheets like Microsoft™
Excel or Wordpad. See Appendix B.
3.5.3 RS485 Communication and Parameters Table
ƒ Click the “View/RS485 Communication/Parameters” item, the
“RS485 Communication and Parameters Table” window will be
displayed.
3.5.4 ModifyAll
ƒ Click the “View/ModifyAll” item, and the “ModifyAll”
window will be displayed.
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3.5.5 Minimize
ƒClick the “Minimize” item to minimize the CN491A-SOFT
graphical interface to an icon.
3.5.6 DevHi/DevLo Setting
ƒ Click the “DevHi/DevLOSetting” item, the Deviation Hi/Lo
setting window will be displayed.
3.5.7 Data Backup
ƒ Click the “Data/Data Backup” to backup the database file,
and a dialog box will be displayed to inform you to backup
the database file.
ƒ Click the “Yes” button, and a dialog box will be
displayed to let you specify the path of file that you want
to backup the database to.
ƒ The database file will have the format of a Microsoft™
Access data file with the extension name “*.mdb”
3.5.8 Reset Database
ƒ Click the “Data/Reset Database” item to clear all the
historical records in the “PVS1” table of the database
file.
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ƒ After clicking the “Data/Reset database” item, a dialog
box will be displayed to inform you whether to clear all
the historical records in the database file or not.
ƒ If you click the “Yes” button, all the historical records
in table “PVS1” of the database file will be deleted.
3.5.9 Exiting
ƒ Click the “File/Exit” item to end CN491A-SOFT. A Yes/No
box will be display. Click “Yes” button to continue Exit or
Click “No” button to cancel Exit.
ƒ Clicking on the “close” button in the control box on the
top-right corner of CN491A-SOFT window will also let you
exit the program.
22
4.0 Database of CN491A-SOFT
ƒ The database that is created by the Data Manager of
Visual Basic is called pv-database.mdb. It is designed to
store the initial setup process Value (PV), and parameter
information essential for operation.
ƒ Whenever the program starts, it fetches the initial
setup variables and parameters from the database pointed
by start-up as described in section 3.1. During the
program run-time, the real-time PV values are written into
the database at the specified interval. To store the
updated parameters into database, please follow the steps
in section 3.3.4.
ƒ The database is composed of two tables: PVS, PVS1. PVS
stores all the parameters and initial settings for all
remote controllers. PVS1 stores the historical data of
process values (PV) for all remote controllers.
ƒ It is a standard Access™ database file, so you can
easily open it by any Access compatible tools. But in the
program run-time, you have to open it by Dataman32.exe
that is attached with Visual Basic tools, because database
is directly linked to CN491A-SOFT through Data Control.
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5.0 Protocol
In the half-duplex, multi-drop system, the Data Terminal
Equipment (DTE) are connected together by two wires as shown in
Figure 2.1. Therefore we must ensure that all transmissions are
carried out in a controlled way and that two transmissions do
not occur simultaneously. Such architectures are normally used
in applications that involve a single master computer
communicating with a number of remote computers.
In order to control access to the shared transmission
messages equitably, a character-oriented data link protocol is
used to operate in a poll-modify mode. When the master wishes
to receive data from a remote unit it sends the remote unit a
poll framing, and then stops and waits until a poll-response
framing is received. If the master wants to send data to a
remote unit, it sends a Modify command and then stops and waits
until a Modify response framing is received.
5.1 ASCII Framing
Framing in ASCII transmission mode is accomplished by the
use of the unique colon “:” character to indicate beginning of
frame and carriage return “CR” and line feed “LF” to delineate
end of frame. The line feed character also serves as a
synchronizing character which indicates that the transmitting
station is ready to receive an immediate reply. See Figure 5.1.
BEG. OF
ADD
CMD
PARA
FRAME ADDRESS COMMAND PARAMETER
:
2-CHAR
2-CHAR
2-CHAR
DATA
6-CHAR
CHECKSUM
CS1+CS2
2-CHAR
EOF
CR
READY TO
RECEIVE
LF
Figure 5.1 ASCII Message Frame Format
5.1.1 Address Field
The address field immediately follows the beginning of frame
and consists of 2 ASCII characters that indicate the userassigned address of remote device.
Each remote unit must be assigned a unique address and only
the addressed remote unit will respond to a query that contains
its address. When the remote unit sends a response, the address
of that unit lets the master know which unit it is
communicating with. The addresses for the remote units can be
set from 1 to 191.
5.1.2 Command Field
The Command Field follows the address field and consists of
24
2 characters (ASCII decimal) that specify the poll or modify
query the master wants to send to the assigned address. See
Command Codes Table, section 6.1
In response to the poll or modify query from the master, the
response message from the assigned address must contain the
same command code.
Poll command code = 65
Modify command code = 66.
5.1.3 Parameter Field
The parameter field also consists of 2 characters. Every
parameter on the remote controller must be assigned a
corresponding code for data exchange. See Parameter and Data
Codes Table, section 6.2.
Example:
Parameter = RAMP
Code = 02
In response to a query from the master, the response message
from the assigned address must contain the same parameter code.
5.1.4 Data Field
The data field consists of 6 characters. It is a 6-digit
decimal number specified in section 6.2, Parameter and Data
Codes Table.
Example:
Data = K thermocouple input
Code = 000001
The “+” character is assumed if the data is unsigned, and
the “-“ character is always the first digit of the data field.
Decimal point character is also assigned a digit.
5.1.5 Checksum Protocol
The Checksum is used to increase security on the RS485 link.
The protocol enables both the master and the remote units to
detect errors in transmission, making the data exchange more
reliable.
The procedure for adding checksum
a. Take the Sum of the ASCII code of the message’s
character in the “ADD”,”CMD”,”PARA” and the “DATA”
fields. Ignore the carries of Sum.
b. Take the 2’s complement of Sum.
2’s Complement Sum=1’s complement Sum + 1
The 2’s complement sum is an 8-bit binary, and can be
formatted with 2-Hex.
c. Take Checksum1 = the hex of the four MSBs of 2’s
25
complement sum
Checksum2= the hex of the four LSBs of 2’s CSum.
Example 5.1: If ADD=01, CMD=65, PARA=27 then checksum = ?.
Code
ADD 0
1
CMD 6
5
PARA 2
7
Sum
1’s C Sum
ASCII
0011 0000
0011 0001
0011 0110
0011 0101
0011 0010
0011 0111
0011 0101
1100 1010
+
1
2’CSum 1100 1011
2’Csum = Checksum = CB (Hex)
So the ASCII frame = “:” + “016527CB” + “CR” + “LF”
Example 5.2: If ADD=01, CMD=66, PARA=26, DATA = -12.5 then
checksum = ?.
Code
ADD 0
1
CMD 6
6
PARA 2
6
DATA 0
1
2
.
5
Sum
1’s CSum
ASCII
0011 0000
0011 0001
0011 0110
0011 0110
0011 0010
0011 0110
0010 1101
0011 0000
0011 0001
0011 0010
0010 1110
0011 0101
0101 1000
1010 0111
+
1
2’CSum 1010 1000
2’Csum = Checksum = A8 (Hex)
So the ASCII frame = “:” + “016626-12.5A8” + “CR” + “LF”
26
5.2 Command Summary
5.2.1 Poll a Parameter from the Assigned Address
START
CHAR
ADD
:
X
CMD
X
6
PARA
5
X
X
CHECK
SUM
CR
LF
X
CR
LF
X
Figure 5.2 Poll Framing
A “Poll Framing” message sent to the RS485 port allows the
master to read a parameter from any controller on the
RS485 link.
Figure 5.2 shows the “poll framing” message format. The
following codes must be entered into its corresponding
field.
ADD: from 0 to 191, the assigned address
CMD: 65 (poll)
PARA: See section 6.2, the Parameter & Data Codes Table.
Checksum: See Section 5.1.5, Checksum Protocol.
START
CHAR
:
ADD
X
CMD
X
6
PARA
5
X
X
DATA
X
X
X
X
X
X
CHECK
SUM
CR
LF
X
CR
LF
X
Figure 5.3 Poll Response Framing
When there is a “Poll” request from the master, only the
assigned address can answer with the “poll response
framing” to inform the master of the parameter and the
data attached with it. The codes of “ADD”, “CMD” and
“PARA” in the “poll response framing” must be the same as
the codes in the “poll framing.” Figure 5.3 shows the poll
response framing.
5.2.2 Modify a parameter to the Assigned Address
START
CHAR
:
ADD
X
X
CMD
6
6
PARA
X
X
DATA
X
X
X
X
X
X
CHECK
SUM
CR
LF
X
CR
LF
X
Figure 5.4 Modify Framing
A “Modify Framing” message to the RS485 port allows the
master to write a parameter to any controller on the
RS485 link.
Figure 5.4 shows the “modify framing” message, and the
27
following codes must be entered into its corresponding
field.
ADD: from 0 to 191, the assigned address
CMD: 65 (poll)
PARA: See section 6.2, the parameter and data
codes table for reference.
See section 5.1.4 and section 5.1.5
Checksum: See Section 5.1.5, Checksum protocol
STA
CHAR
:
ADD
X
X
CMD
6
6
PARA
X
X
DATA
X
X
X
X
X
X
CHECK
SUM
CR
LF
X
CR
LF
X
Figure 5.5 Modify Response Framing
In response to the “Modify” request from the master,
only the assigned address can answer the “Modify
response framing” to inform the master that the “modify
command” is followed completely. The codes of the “ADD”,
“CMD” and “PARA” in the “Modify response framing” must
be same as the codes in the “modify framing”.
Figure 5.5 shows the Modify Response framing.
28
6.0 Command, Parameter and Data Codes Tables
6.1 Command Codes Table
CMD
Poll
CODE MEANING
ACTION
65 Read the parameters with Only the master can issue the
data from the selected
“poll” request. It allows the
address by the master
master
to
retrieve
the
parameter with data from the
selected remote address.
The “poll framing” is defined in
Figure 5.2
Only the selected remote
address is permitted to answer
the “poll response framing”,
which is defined in Figure 5.3,
to the master.
66
Write
the
parameters
with
1.
Only
the master can issue the
Modify
data from the master to the
“modify” request, It allows the
selected remote address
master to write the parameter
with data to the selected
remote address.
2. The “modify framing” is defined
in Figure 5.4.
3. Only the selected remote
address is permitted to answer
the “modify response framing”,
which is defined in Figure 5.5,
to the master.
29
6.2 Parameter and Data Codes Table
PARAMETERS
PARA
ASP_1
DATA
CODE DESCRIPTION
01
CODE
Alarm 1 Set Point Value or Dwell
Time (A1_SF = T0_ON or
T0_OFF)
RAMP 02 Ramp Rate
VALUE
XXXX.X Low Scale to High Scale Value (for
Full Scale Alarm), -110.0 to 111.0°C
or -199.9 to 199.9 °F (for Deviation
and Deviation Band Alarm),0 to
999.9 minutes (for Dwell Time)
**18.0 °F
XXXX.X 0 to 55.55 °C/minute or
0 to 99.9 °F/minute
XXX.XX 0 to 100 % ** 0.0
OFST
SHIF
03 Offset Value for Manual Reset
04 Shift Process Value
PB
05 Proportional Band of Output 1
TI
TD
06 Integral (Reset) Time of Output 1
07 Derivative ( Reset) Time of Output XXXXXX 0 to 1000 Seconds ** 40
AHY_1 08
1
Hysteresis of Alarm 1
XXXX.X -111.0 to 111.0 °C or -199.9 to
199.9 °F ** 0.0 °F
XXXX.X 0 to 200 °C or 0 to 360 °F
0: For ON-OFF Control / **18.0 °F
XXXXXX 0 to 3600 Seconds ** 120
XXXX.X 0 to 11.0 °C or 0.1 19.9 °F **0.0
HYST 09 Hysteresis of On/Off Control
ADDR 10 Address of the Unit for
XXXX.X 0 to 11.0 °C or 0.1 19.9 °F **0.0
LO_SC
NONE
Communication
Low Scale of Range Adjust for
your process
1 to 199, Poll (Read) Only
PL1
13 Power Limit of Output 1
XXXX.X Minimum Value for the Selected
Input (INPUT) to High Scale (HISC)
**000.0 °F
XXXX.X Low Scale (LOSC) to maximum
value for the selected Input (INPUT)
**999.9 °F
XXXXXX 0 to 100 % **100
PL2
14 Power Limits of Output 2
XXXXXX 0 to 100 % **100
11
HI_SC 12 High Scale of Range Adjust for
your process
30
PARAMETERS
PARA
INPT
CODE
15
DATA
DESCRIPTION
CODE
Input Type Selection
000000
00 0001
000002
000003
000004
000005
000006
000007
000008
000009
000010
000011
000012
000013
000014
000015
UNIT
16 Units Selection
000000
000001
000002
VALUE
J-tC : J Type T/C
** K-tC : K Type T/C
t-tC : T Type T/C
E-tC : E Type T/C
b-tC : B Type T/C
r-tC : R Type T/C
S-tC : S Type T/C
n-tC : N Type T/C
Pt_dn : PT100 DIN
Pt_JS : PT100 JIS
4-20 : 4 to 20 mA
0-20 : 0 to 20 mA
0-1V : 0 to 1V
0-5V : 0 to 5V
1-5V : 1 to 5V
0-10V : 0 to 10V
C : Degree C
** F : Degree F
P.U: Process Unit
(Voltage or Current Input)
RESO
17
Resolution Selection
000000
no.dP: No Decimal Point
1.dP: 1 Digit Decimal
000002 2.dP: 2 Digit Decimal ( Only for
000001
Linear Voltage or Current Input)
CONA
18
Control Action of Output 1
000000
dirt : Direct (Cooling) Action
000001 ** rEvr : Reverse(Heating) Action
31
PARAMETERS
PARA
A1_MD
CODE
19
DATA
DESCRIPTION
CODE
Alarm 1 Mode
000000
000001
000002
000003
000004
000005
A1_SF 20 Alarm 1 Special Function
000000
000001
000002
000003
VALUE
** dv_hi : Deviation High Alarm
dv.Lo : Deviation Low Alarm
db.hi : Deviation Band High Alarm
db.Lo : Deviation Band Low Alarm
FS.hi : Full Scale High Alarm
FS.Lo : Full Scale Low Alarm
** nonE : No Special Function
LtCh : Alarm with Latch Function
hoLd : Alarm with Hold Function
Lt.ho : Alarm with Latch and Hold
Function
000004
to.on : Dwell Timer ON as
Timeout
000005
CYC
21
CCYC
22
C_PB
23 Cooling P Band
D_B
PV
SV
MV1
MV2
to.oF : Dwell Timer Off as Timeout
XXXXXX 0 to 99 Seconds, 0 for Linear
Current / Voltage Output **20
XXXXXX 0 to 99 Seconds, 0 for Linear
Current / Voltage Output **20
XXXX.X 0.0 to 200.0 °C or
0.1 to 360.0 °F ,**18.0 °F
XXXX.X -111.0 to 111.0 °C or
-199.9 to 199.9 °F , ** 0.0°F
None Poll (Read) Only
Proportional Cycle time of
Output 1
Cooling Cycle Time
24 Dead Band for PB and CPB
25 The Process Value
26 Set Point Value
XXXX.X From Low Scale to High Scale
Value
None 0 to 100.0%, Poll (Read) Only
27 Amount of Control Output 1
28 Amount of Control Output 2
None
0 to 100.0%, Poll (Read) Only
Note: ** Denotes the Default Setting
32
7.0 Programming Examples
Example 7.1:
The master wants to read the Process Value (PV) from the
Remote address (03). What is the “ASCII framing” that
has to be sent to the RS485 port by the master?
Answer:
Refer to the “Poll framing” format shown below.
START
CHAR
ADD
:
X
CMD
X
6
PARA
5
X
X
CHECK
SUM
CR
LF
X
CR
LF
X
ADD = “03”, the assigned remote address
CMD = “65”, Poll command
PARA = “25”, code for “PV”. Refer to the Parameter and
Data Codes Table in section 6.2.
Checksum = “CB”. To get the checksum, follow the steps
as described in section 5.1.5.
So the “ASCII framing” = “:” + “036525CB” + “CR” + “LF”
Note: After sending the “poll framing” to the RS485 port, the
master must stop and wait until it receives a “poll
response framing” from the assigned remote address “03”
on the RS485 port.
Example 7.2:
The master wants to write the Setpoint Value (SV) to the
Remote address(01) with a value 99.5. What is the “ASCII
framing” that should be sent to the RS485 port by the
master?
Answer:
Refer to the “Modify framing” format shown below.
START
CHAR
:
ADD
X
X
CMD
6
6
PARA
X
X
DATA
X
X
X
X
X
X
CHECK
SUM
CR
LF
X
CR
LF
X
ADD = “01”, the assigned remote address.
CMD = “66”, Modify command.
PARA = “26”, code for “SV”. Refer to the Parameters and
Data Codes Table in section 6.2.
Checksum = “96”. To get the checksum, follow the steps
as described in section 5.1.5.
So the “ASCII framing” =
“:” + “0166260099.596” + “CR” + “LF”
33
Note: After sending the “Modify framing” to the RS485 port,
the master must stop and wait until it receives a
“Modify response framing” from the assigned remote
address 01 on the RS485 port.
Example 7.3:
How can you program the Com Port if using an RS232/485
converter box?
Answer:
If using an RS232/485 converter box, switching between
transmitting and receiving is controlled by the RTS
(Request to Send) handshaking signal.
When the PC wishes to transmit data to a remote unit, the
PC must enable the RTS first. On the contrary, when the PC
wishes to receive data from a remote unit, the PC must
disable the RTS.
So the following steps are needed for programming:
1. Set up the Com Port
2. Enable the Com Port
3. Enable RTS
4. Move the TX Framing to the Com Port
5. Wait until TX Framing has finished transmission
6. Disable the RTS, and wait for the RX response
7. If timed out (about 0.4 second for poll (read)
command, and 0.8 second for modify (write)
command), then restart
8. Read the RX Response in the Com Port
9. Restart next cycle and go to step 3.
Note: If the RTS signal is not controlled in time, for example,
your program enables/disables the RTS during TX/RX, but
the Com Port does not respond immediately, a framing error
will occur and causes transmission failure.
34
8.0
DDE to other Applications
The CN491A-SOFT supports DDE communication. Users can write
their own application to read/write data from/to CN491A-SOFT.
1.This version now supports reading PV, SV, MV1, MV2, PB,
TI, TD and writing SV, PB, TI, TD data for all remote
addresses.
2.The DDE protocols are as follows:
Application : CN491A-SOFT
Topics : frmDDE
Items : PV_DATA ( n )
SV_DATA ( n )
MV_DATA ( n )
MV2_DATA ( n )
PB_DATA ( n )
TI_DATA ( n )
TD_DATA ( n )
(n is the remote address)
3.Please create DDE link in run-time. You can reference the
following codes. Maybe it is suitable to substitute them
during initialization like form load:
Text1.LinkMode = vbLinkNone
Text1.LinkTopic = ”CN491A-SOFT|frmDDE”
Text1.LinkItem = ”PV_DATA(1)”
Text1.LinkMode = vbLinkAutomatic
Assume Text1 is a text contro1 that you want to link to PV
of remote Address 1.
4. You can write back to remote controllers through DDE
LinkPoke. The parameters that can be modified are: SV, PB,
TI, TD. The DDE protocol is similar to item 2. A sample
code is illustrated as follows:
Text2.LinkMode = vbLinkNone
Text2.LinkTopic = ”CN491A-SOFT|frmDDE”
Text2.LinkItem = ”SV_DATA(1)”
Text2.LinkMode = vbLinManual
Text2.Text = InputBox(“Enter New SV:”)
Text2.LinkPoke
Text2.LinkMode = vbLinkAutomatic
Assume Text2 is linked to SV of Remote node 1. The CN491ASOFT will check the data poked from DDE. If it is different
from the parameter in database, communication will be
started to set the corresponding parameter to a new value.
5. Copy & Post Link mechanism to create DDE link in design
time is not supported.
35
8.1 DDE Demo
Design a DDE to read/write data from/to Address01
Design Time:
Figure 8.1 the from DDE Demo
ƒ Design a form like Figure 8.1
ƒ Write source code:
Option Explicit
Private Sub cmdSetSV_Click()
Text2.LinkMode = vbLinkNone
Text2.LinkTopic = "CN491A-SOFT|frmDDE"
Text2.LinkItem = "SV_DATA(1)"
Text2.LinkMode = vbLinkManual
Text2.Text = InputBox("Enter SV")
Text2.LinkPoke
Text2.LinkMode = vbLinkAutomatic
End Sub
Private Sub cmdSetTI_Click()
Text6.LinkMode = vbLinkNone
Text6.LinkTopic = "CN491A-SOFT|frmDDE"
Text6.LinkItem = "TI_DATA(1)"
Text6.LinkMode = vbLinkManual
Text6.Text = InputBox("Enter TI")
Text6.LinkPoke
Text6.LinkMode = vbLinkAutomatic
End Sub
36
Private Sub cmdSetTD_Click()
Text7.LinkMode = vbLinkNone
Text7.LinkTopic = "CN491A-SOFT|frmDDE"
Text7.LinkItem = "TD_DATA(1)"
Text7.LinkMode = vbLinkManual
Text7.Text = InputBox("Enter TD")
Text7.LinkPoke
Text7.LinkMode = vbLinkAutomatic
End Sub
Private Sub cmdSetPB_Click()
Text5.LinkMode = vbLinkNone
Text5.LinkTopic = "CN491A-SOFT|frmDDE"
Text5.LinkItem = "PB_DATA(1)"
Text5.LinkMode = vbLinkManual
Text5.Text = InputBox("Enter PB")
Text5.LinkPoke
Text5.LinkMode = vbLinkAutomatic
End Sub
Private Sub Form_Load()
Text1.LinkMode
Text2.LinkMode
Text3.LinkMode
Text4.LinkMode
Text5.LinkMode
Text6.LinkMode
Text7.LinkMode
=
=
=
=
=
=
=
Text1.LinkTopic
Text2.LinkTopic
Text2.LinkTopic
Text3.LinkTopic
Text4.LinkTopic
Text5.LinkTopic
Text6.LinkTopic
Text7.LinkTopic
vbLinkNone
vbLinkNone
vbLinkNone
vbLinkNone
vbLinkNone
vbLinkNone
vbLinkNone
Text1.LinkItem
Text2.LinkItem
Text3.LinkItem
Text4.LinkItem
Text5.LinkItem
Text6.LinkItem
Text7.LinkItem
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"CN491A-SOFT|frmDDE"
"PV_DATA(1)"
"SV_DATA(1)"
"MV_DATA(1)"
"MV2_DATA(1)"
"PB_DATA(1)"
"TI_DATA(1)"
"TD_DATA(1)"
37
Text1.LinkMode
Text2.LinkMode
Text3.LinkMode
Text4.LinkMode
Text5.LinkMode
Text6.LinkMode
Text7.LinkMode
=
=
=
=
=
=
=
vbLinkAutomatic
vbLinkAutomatic
vbLinkAutomatic
vbLinkAutomatic
vbLinkAutomatic
vbLinkAutomatic
vbLinkAutomatic
End Sub
ƒ Make an executable file named: DDECLT.exe
Run Time:
Figure 8.2 The DDECLT linking CN491A-SOFT
ƒ Execute the file DDECLT.exe, and a form like Figure 8.2
will appear. The DDECLT.exe is now linked to CN491A-SOFT!
The corresponding text box shows the linked data.
ƒ To write SV, PB, TI, TD to Address 01 through DDECLT.exe,
click the corresponding Set__ button. An input box will
show; enter a set value and click “OK” button to write it to
CN491A-SOFT or click “Cancel” button to cancel it.
38
9.0 Appendix
Appendix A
Open the database file named: PV_Database.mdb by
Datman32.exe.
ƒ execute Datman32.exe in run time
ƒ open the file PV_Database.mdb, you will see a form like
Figure 9.1.
Figure 9.1 Opening database in run time
ƒ Click the “Refresh” button. You may view the new updated
data but do not edit it unless it is necessary.
39
Appendix B
Open the Parameters file created in section 3.5.2 by an
application program such as Microsoft Excel. A spreadsheet as
shown in Figure 9.2 will open that can be edited or printed out
for reference.
Figure 9.2 Parameters file edited by Microsoft Excel
40
Appendix C
Figure 9.3 Trend Recording Print-out
41
Notes
42
Notes
43
Notes
44