Applies To:
  • CitectSCADA x.x

Summary:
I have serial communication problem between Citect and my PLC. 

Solution:
Use the following procedure:
  1. Get a RS232/RS422/RS485 serial communication analyser.
  2. Connect in between Citect and the PLC.
  3. See if anything is transmitted by Citect? If no, the problem is in Citect configuration. Make sure that the driver is actually loaded by looking at "page driver" in the Citect kernel.
  4. Does the content of the message from Citect look like something that the PLC can understand? If no, the problem is in Citect configuration.
  5. If there is no transmission of an answer by the PLC:
    Check whether the PLC address is correct.
    Check the cable
    Check the transmission parameter (baud rate, parity, data bits, stop bits)
    Check the mode (peer to peer, master slave and etc..)
    If everything is set correctly, but there is still a problem, call the PLC supplier.
  6. If there is a transmission of an answer from the PLC, but the PLC does not come on line, get a "debug <port> all" and send the syslog.dat to Citect Support.
  7. If the PLC does come online, but the problem is intermittent, get a "debug <port> error" and send the syslog.dat to Citect Support
  8. If the PLC does come online, but the problem only happens when writing to the PLC, get a "debug <port> write" and send the syslog.dat to Citect Support.

Please also supply Citect support with your citect.ini, Boards, Ports and Units .DBF files. Citect support will also require the following information: O/S used (NT, Win95, WFW), Citect version (1, 2, 3.21, 3.4, 4.2, 5.0 and etc..).

 

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