RMQ GetMessage fails randomly

Hey there!
We have a setting, where a remote C# application sends a complex datatype (RECORD) which consists of several NUMs, DNUMs, BOOLs and a single STRING via RWS (Robot Web Services 1.0).

At first, it seemed to work. But after a longer test we noticed the robot failing to read the message with ERRNO=ERR_RMQ_INVMSG (invalid Message) randomly.

At first, we considered the 'underscore' inside the String as the source of the fault. But we are not able to reconstruct this behaviour. Sometimes it works, sometimes it fails.

Are there things we need to consider? Are there other ways to debug the message? It is hard to point out what causes the fault, because I cannot see the content of the sent message on the robot-side.

Any kind of hints or clues heartly welcome!  


  • Hi Oliver,

    Our robot cell currently has exactly the same problem.
    We got the suggestion that the very first RMQ message reserves a certain memory range in the controller.
    Later on when a larger message would arrive, problems could appear.
    A suggested solution was to start with a larger 'dummy' message, but unfortunately this does not seem to work for us.

    Please keep me posted when you make any progress on this problem.

  • Hello,
    This issue has been brought to R&D´s attention.

    Nils Olofsson
    PC Software Support Engineer

  • Oliver_L
    Oliver_L NRW, Germany
    edited September 2020
    Good to hear that!

    Today, we spent some hours testing. We think that we found a pattern:
    It works fine, as long as the overall length of the RMQ message is equal or longer as the longest length received so far.

    Only a restart allows shorter messages to be successfully received again.

    For Example:
    [400,200,19,"Barcode",10,FALSE] -> works (length=29)
    [400,200,19,"Barcode",10,TRUE] -> fails (length=28)
    [400,200,19,"Barcode",101,TRUE] -> works (length=29)

    Note: It doesn't matter which data field ist shorter, overall length seems to matter.
  • This bug will be fixed for RW 6.12 and 7.2

    Nils Olofsson
    PC Software Support Engineer