Omron PLC and temperature meter 485 serial communication realization - Database & Sql Blog Articles

RF cable can be customized for other specifications

Omron plc communicates with other instruments or devices (whether it is OMRON instrument or third-party instrument), it should use the serial communication module or template with protocol macro, according to the communication protocol of the instrument or device to make the corresponding program, establish the corresponding communication channel, The meter can be read and written.

I have written communication between PLC and third-party temperature instrument for customers, and I am presenting it to you. Please correct me.

The PLC used is OMRONC200HE-CPU42, equipped with communication module C200HW-COM06, and uses its A port (RS485) to communicate with the temperature meter TTM-120.

1. The temperature instrument "Shenwang" TTM-120 communication protocol is used:
EIA standard: RS485
Communication: Station 1 ~ 31
Transmission: Half-duplex communication code: ASCll7 bit (except BCC) 8 bits (MSD bit = 0)
Interface mode: 2-wire communication speed: 1200, 2400, 4800, 9600
Communication distance: 500Mmax
Character: Start bit: 1 stop bit: 1/2 bit data: 7/8 bit check: none / odd / even
BCC check: pre/no choice of mailing address: 1~99
Communication format:
Read data: STX (02H start code) + address (2 digits) + R + identification code (3 digits) + ETX (03H end code)
Instrument return: STX (02H start code) + address (2 digits) + ACK (06H response) + identification code (3 digits) + data (5 digits) + ETX (03H end code)
Write data: STX (02H start code) + address (2 digits) + W + identification code (3 digits) + data (5 digits) + ETX (03H end code)
Meter return: STX (02H start code) + address (2 digits) + ACK (06H response) + ETX (03H end code)
Error message response: STX (02H start code) + address (2 bits) + NAK (15H error response) + error format (1 bit) + ETX (03H end code)

2, using the protocol macro software CX-PROTOCOL as the protocol macro program can be used in the CX-PROTOCOL existing system standard protocol COPY to the new program, and then modify, of course, can also be re-programmed.
Select the PLC model used in the DEVICES of the newly created program.
The communication port A parameter setting mode is: PROTOCOLMACRO; and the baud rate and other parameters are set in the communication format of the meter.
There are several contents in the protocol macro program: mainly sending a list of information; accepting a list of information; these two tables are the basic procedures of the protocol macro. Then there are specific forms of transmission and acceptance, read and write forms of other functions, and read and write forms of other functions of the meter.
I made four kinds of macro programs based on the various formats in the meter protocol, as follows:
Send a list of information:
1 write data: SD (01) _1
:STX
:ETX
Data format: variable format ($(R(2), 5))
Address format: ASCll variable format ($(R(1), 2)
"W": Write request identifier (meter function parameter: write set value) "space SV"
Data Format: + +"W"+"SV"+($(R(2),5))+
2 read request: SD (02)_1
Address format: ASCll variable format ($(R(1), 2)
"R": read request identifier (meter function parameter: read in process value) "PV1"
Data Format: + +"R"+"PV1"+
Accept the list of information:
1Received response: RV(01)_1
"ACK": Response accepted data format: + +"ACK"+
2 Accepted data: RV (02)_1
Data format: The variable format (&(W(1),*)) is stored in the received data format specified by the PLC: +(&(W(1),*))+
Write command settings:
Number: 050
Command: Send & accept send command: SD(01)_1
Receive command: RV(01)_1
Read command settings:
Number: 051
Command: Send & accept send command: SD(02)_1
Receive command: RV(02)_1
The setup is completed and downloaded to the PLC.

3. Use CX-PROGRAMMER as the communication program to complete the communication with the instrument with the protocol macro PMCR:
Three operands: One: Control word: Port + Protocol macro Serial number 2: The first address of the transmitted data is 2/3 words, the first word is the number of instructions; the next word is the instrument address;
For the write command, one more word is set value three: the first address of the received data is 4 words, the first word is the number of command words; the next two words are the received 5 bits of data.
For the write command, the operand is a dummy word, and there is no practical meaning to read the instruction: PMCR#1051 port=1synthesis number 051 (readout)
DM0000DM0000=#0002DM0001=#0001
DM0030DM0030=#0004DM0031~DM0033=Data Write Command: PMCR#1050 Port=1Serial Number 050 (Write)
DM0020DM0020=#0003DM0021=#0001DM0022=Setting value
DM0040 (dummy)
Protocol macro execution flag: port one (A): alpha machine is IR289.08CQM1H is IR207.08
Port 2 (B): α machine is IR289.12CQM1H is IR207.12
When this variable = 0, the PMCR command can be executed to execute only one communication sequence per port, and the execution pulse of the PMCR instruction can be generated in different time periods.

4. For several meters, each station sets a different station number, and it can be read and written by the program separately. Only the instruments with the matching address can respond.