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  1. #1

    Johnson Controls NAE site: Intermittent unreliable values of -28672

    Hello,
    I have a control system that has 2xNAE5510's and 1xNAE4510. All at version 5.2.0.5400
    On one of the 55's I have a number of controllers on the same N2 bus that are reporting intermittent values of '-28672'. Temperature and setpoint inputs, as well as analog outputs randomly display the value for a couple seconds and then go back to normal.

    I have qty10 TC9102's and one DX9100 that are having the same issues.. all on the same bus. There are number of other N2 devices on the bus that are not affected, including other DX9100s, VMAs and UNTs.

    The controllers themselves do not go offline, just the same value (-28672) is displayed intermittently on each system. They are not geographically near each other on the bus.
    This has been an issue on this site since installation, approx. 5 years ago.
    We had tried redownloading programs, changed sensors (although both input and output values are affected), changed controllers but no luck.. I am thinking there are software/firmware conflict issues??

    If anyone has seen this issue before or could offer a resolution any help would be appreciated.


    Thanks,
    Greg

  2. #2

    No help/suggestions on this one?

    Nobody ran into something like this before?
    Any help would be appreciated,
    Greg

  3. #3
    Join Date
    May 2006
    Posts
    649

    N2

    Quote Originally Posted by Gpolk View Post
    Nobody ran into something like this before?
    Any help would be appreciated,
    Greg
    Power cycle the working DX9100 and see what version it is. Then power cycle the effected one and check this version.

    Do you have any other TC9102 that are on the network that is not causing this problem?

  4. #4
    Join Date
    Apr 2007
    Location
    Upstate NY
    Posts
    78
    I recently came across a bulletin on the acbs site that indicated grounding one side of the transformer secondary, as required by nec if primary voltage is over 150 v to ground, can cause ground loops in the controller causing problems. Cycling power usually cleared it up for me. They recommend a 24-24v isolation transformer in those situations. Mine was on a unt, not a dx, but sounds similar.



    Sent from my iPhone using Tapatalk

  5. #5
    Had similar problem 2 weeks ago. 2 dx9100 would show sensors going offline or 28672 value. The xt's had duplicate addresses with others on different dx9100 but same n2 bus. Re-assigned addresses. Problem solved.

  6. #6
    Join Date
    Feb 2008
    Location
    Washington State
    Posts
    28
    Are there any expansion modules (XT-910X-yyyy) on the DX-9100s on the affected N2 Bus?

    If so what are the addresses of the XTs?

    In this case they may have the same addresses as the N2 devices (or XP) with the affected values. The XT / XP module on a DX-9100 XT Bus can respond to N2 polls simultaneously with other devices causing strange values to be displayed intermittently.

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