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  1. #1
    Join Date
    Aug 2007
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    BACnet Communications Troubles...

    I've been running into some communication issues with BACnet network (I/A UNC / Tridium )

    Dealing with I/A UNC with intermittent blips that show all controller objects as being "down" when looking at them at Work Place Pro, but then all returns to normal after a few seconds. At WPT, everything runs without any problems, and there is no communication timeout (NaN) which would indicate a real loss of communication from the UNC through WPT.

    Spoke to a colleague who advised that there is a limit to the number of switches that can be placed on a network "backbone"(?) and that this limit may be exceeded causing these issues.

    Anyone run into anything like this? Is my collegues suspicions correct?

    Thank you.

  2. #2
    Join Date
    Feb 2007
    Sacramento, CA
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    Check the jar file

    You don't say which panel you have, R2 or AX. Since TAC is not pushing AX I'll assume you have R2. Check for a newer version of the bacnet ja file. Before I left my last job they found out the jar file (from Tridium) had problems. Also they said there was a limit on how many bacnet devices could be on the network. I don't know what that limit is but exceeding it caused communictions issues as well. Hope this points you in the right direction.

  3. #3
    Join Date
    Aug 2007
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    Thanks for your input. Yes it is R2.

    The BACnet jar , yes, I am aware of the problems with this, and we installed the last known good one. As for device utilization, the BACnet controllers are not tied to the UNC, but rather to a MNB1000 Plant controller connected by Ethernet to the same switch as the UNC. There is only one MSTP device attached to the MNB1000 plant controller, which is an ABB VFD BACnet controller.

    I guess I should have been more definitive in my first message.

    The commonality has the controllers (MNB1000s) being tied to the same switch as the UNC.

    But it is indeed an unusual issue as I can connect through WPT to the controller and see all points communicatin and updating as they should. Yet, with WPP shadow object in the background, the BACnet objects read offline for a couple of moments, and there is no interuption at the WPT level.

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