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P1-540 CPU Serial Communication with Pace 1000 Pressure Reference

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  • P1-540 CPU Serial Communication with Pace 1000 Pressure Reference

    I'm having difficulty communicating with a Pace 1000. It uses a protocol SCPI. I'm trying to send *IDN? to the Pace and receive system information back. It appears the string is sent out using the ASCII OUT instruction. The ASCII Out.Complete bit does go high after enabling the instruction. I don't know if the Pace receives it. The ASCII IN instruction indicates the ASCII In.Complete bit goes high and so does the ASCII In.FCTimeout. It appears no response has been received. Any ideas?

  • #2
    IIRC, the complete only means that the instruction put the bits on the wire. No actual comms is implied.

    Docs of the Pace device - or just a pic of the setup
    BAUD, start/stop bits, parity.... does the Pace device use RS-232 or RS-485 (if 485, is there a NODE address?)
    Do you have to specify a node address first?
    My TDK power supplies have to be 'addressed' before they respond. I have to send something like [ADR 2 crlf] before the PSU at address 2 will respond.
    Any idea of what the idle voltage is of the Pace device.


    • #3
      Try troubleshooting with a PC terminal program. At least you can see if the data is being sent from the PLC. A good simple free Hyperterminal substitute is called 'Termite' from CompuPhase. Just set your comm parameters correctly and you should see the string. I'd try sending the string from the terminal program first to see if the PACE unit even responds back.


      • #4
        Thank you for the suggestions. I appreciate it. It turns out that the Pace comm port was confusing to me. Usually connection from tx is made to rx and tx to rx. I had to connect the rx to rx and tx to tx. From there it was a matter of manipulating the received data to my application. I did end up using a terminal program to assist in troubleshooting.