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How to test if your PLC and other device are communicating with each other?

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  • How to test if your PLC and other device are communicating with each other?

    As the title states I was wondering if there is a simple task I can do to check if my external device is communicating with my do more plc through ascii. I want to test if I have wired the device up correctly and test if my device is actually sending data over however I am very new with the do more series and unexperienced with using ASCII through the Rs-232 port. Any guidance or advice is welcomed!

    Using a BRX do more PLC - BX-DM1E-36ER3-D and think I may have to issue a streamin command however when I tried doing so following the Barcode scanner video I wasn't getting a reading.


  • #2
    Hi Mark,
    If you are using a barcode reader as input to the PLC then you will basically see in the memory area the information that was scanned.
    If you are not receiving anything in the memory area when using the barcode scanner, check the cable connection.
    If you are receiving information but the information is not readable, check the port configuration. (Baud, Number of data bits, Stop Bits, and parity)

    Communication to another device that will receive and send data we can do several things to determine if communication is good.
    Serial protocols such as Modbus RTU is a master-slave type. Once we send information out of the port we can set up timers to ensure that a response is received. On the slave side, a heartbeat can be set up to determine if the master has stopped sending information. A heartbeat is usually a bit that is reset every time the master communicates to the slave. If the bit does not get reset within a time frame then we know communication is lost.

    Here are some posts dealing with serial communication with the BRX:

    This post is a sample of a heartbeat.

    Hope this helps you out.

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