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  • Snaplink NULL byte issue

    We purchased 6 snaplinks (SL485K-001) and are using FTDI USB-RS485-WE-1800-BT adapters connected to a Windows embedded computer.

    We have successfully paired two sets and are able to communicate with a MODBUS unit.

    The other two units pair but but we are seeing a NULL byte (1st byte) followed by the expected bytes, which results in a communication failure.

    We purchased 4 additional snaplink units and all four are experiencing the same problem.

    We have swapped out USB-485 adapters, tried different combinations of pairing, network ID, Channel, Buffering Timeout, Buffering Threshold, and Inter-Character Timeout.

    We have used EasySet to factory default the devices, and also attempted to load the SNAPpy Image SNAP_Link-RF100-2.4.9.spy.

    Curiously only one of the four currently being tested will even display the two spy files when selecting File>>Upload from the EasySet menu. The other three just display a blank list.

    Downloaded the Portal software and connected to each unit. All show Firmware version: 2.4.19 (Out of Date).

    At this point I am at a loss as to how two sets work just fine, but the other 3 sets do not.

    Any guidance at this point would be greatly appreciated.

    Thanks,

    Brad

  • #2
    In regards to the blank screen when trying to upload the script ....... http://forums.synapse-wireless.com/s...ead.php?t=3529

    Curiously only one of the four currently being tested will even display the two spy files when selecting File>>Upload from the EasySet menu. The other three just display a blank list.

    Downloaded the Portal software and connected to each unit. All show Firmware version: 2.4.19 (Out of Date).
    In regards to Portal reporting and out of date firmware that is expected and will always be that way as the SNAP link firmware is locked at 2.4.9 or 2.4.19.


    Do the two units that work also fail in the other setup that is showing the "null byte" character?

    The SNAP link simply take whatever data it receives ad sends it there are not modes where a null byte would be added.

    Comment


    • #3
      gvoce,

      Downloaded the SNAP_Link-RF100-2.4.19.spy file.

      Took two units that previously showed a blank list and Uploaded the 2.4.19 spy file and then factory reset.

      Connected these two units to the same Modbus Unit and PC that the other two pair are successfully working with.

      Results were the same. When using these two snaplinks we still see NULL 1st byte on received data.

      I understand that the snaplinks are suppose to just pass the data from one to the other, but we are testing this on the same equipment. 2 snaplink pairs work, 3 pairs do not.

      Thanks for the reply.

      Brad

      Comment


      • #4
        Are all the SNAP links using the same SNAP_Link-RF100 spy file?

        Need to get all the SNAP link running the same script, sane setup to help determine what is causing this issue.

        Comment


        • #5
          gvoce,

          The working pairs have been deployed to the field, so all I have to work with currently is the one pair that I have update to the 4.2.19 spy file.

          We did not check what firmware was on the working pairs before deploying. They were working and we didn't want to do anything to them that might somehow cause them to stop working.

          Brad

          Comment


          • #6
            I have looked through the Easyset configuration and the SNAP link script and can find no condition where the device would introduce a null byte.

            Comment


            • #7
              gvoce,

              I was able to resolve the problem by adding biasing resistors (http://en.wikipedia.org/wiki/RS-485) to the PC connected Snaplink.

              Thanks for taking a look at this for me.

              Brad

              Comment

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