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  1. #1
    Join Date
    May 2007
    Location
    PA
    Posts
    11

    JCI N2 Bus Devices

    My company took over a few sites that have jci controls in them. I haven't had issues connecting to the bus and seeing the whole network at some sites. This one site I can connect to each controller by themselves but once I go to the bus I cant see anything. Ive even taken the FX-60 off of the bus and it still will not work. Im using a windows 7 laptop with HVAC PRO and a LP-KIT200-000C adapter. Like I said my other sites work good just this one is giving me trouble.

  2. #2
    Join Date
    May 2006
    Posts
    345
    What are your N2 Bus Voltages?

    N2+ to Ref should be 2.45 to 2.98 VDC
    N2- to Ref should be 2.06 to 2.54 VDC
    N2+ to N2- should be .36 to .92 VDC

    Are end of lines configured properly?

    If the voltages aren't correct I would start breaking the trunk in sections going from the FX60 out until you see where the issue is.

  3. #3
    Join Date
    May 2007
    Location
    PA
    Posts
    11
    I did not measure the bus voltage and I don't know if the end of lines are configured properly. When I connect to the JACE I see everything ok. Also Im using HVAC Pro 8.08

  4. #4
    Join Date
    Jul 2002
    Posts
    819
    Quote Originally Posted by jradz3829 View Post
    This one site I can connect to each controller by themselves.
    When you connect individually is that controller on or off the network. In other words do you remove it from the net when you hook up to it?

  5. #5
    Join Date
    May 2007
    Location
    PA
    Posts
    11
    The controller is off the bus.

  6. #6
    Join Date
    Nov 2005
    Location
    Shreveport, Louisiana
    Posts
    2,324
    So do you have the N2 bus troubleshooting guide? This can help. Have you checked for duplicate dip switch addresses. One of your devices is prolly screwed up and draggin down the bus. Divide and conquer.
    UA Local 141

  7. #7
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    829
    How many devices are on the bus? I had an issue once where when I connected to N2 bus directly with a RS485 adapter with the JACE disconnected and I could not communicate with the devices but yet the JACE could. Turned out there were too many devices, I think 75 total, but yet the JACE could communicate with them. Com was slow for the JACE. Split the bus and all was good.

  8. #8
    Join Date
    May 2007
    Location
    PA
    Posts
    11
    I couldn't find how many were on the bus still looking for all of the control prints. Didn't check for duplicate addresses also I don't have the trouble shooting guide. I'll have to check this all out on my next visit.

  9. #9
    Join Date
    Mar 2008
    Location
    NC
    Posts
    1,445

  10. #10
    Join Date
    Apr 2005
    Location
    2444 Washington Blvd, Suite 100 Ogden, UT
    Posts
    335
    Quote Originally Posted by controlgeek View Post
    What are your N2 Bus Voltages?

    N2+ to Ref should be 2.45 to 2.98 VDC
    N2- to Ref should be 2.06 to 2.54 VDC
    N2+ to N2- should be .36 to .92 VDC

    Are end of lines configured properly?

    If the voltages aren't correct I would start breaking the trunk in sections going from the FX60 out until you see where the issue is.
    Two tools that you might consider to assist you in testing the bus are the ComBus Quick Tester from B&B Electronics or the S2USB485 from S Squared. Both of these products will give you additional information that may assist with your troubleshooting.
    Steve Jones
    Managing Partner
    The S4 Group, Inc.

  11. #11
    Join Date
    May 2007
    Location
    PA
    Posts
    11
    We do have a com bus quick tester (ms-cqt485-0) at the office.

  12. #12
    Join Date
    Apr 2005
    Location
    2444 Washington Blvd, Suite 100 Ogden, UT
    Posts
    335
    Many of our integration partners have found this to be a very good diagnostic tool. Not only does it give you the voltages but it scans the bus to confirm what devices (and N2 addresses) it can reach. Having this available, plus using the divide and conquer approach should get you to the root cause. Check the polarity of the N2 connection on all devices. You might find a device that is simply misbehaving and putting garbage on the network. You might find EMF interference from a ballast causing problems. Etc.
    Steve Jones
    Managing Partner
    The S4 Group, Inc.

  13. #13
    Join Date
    May 2007
    Location
    PA
    Posts
    11
    Thanks everyone I will be going to the site next week to work on the problem.

    Sent from my DROID RAZR using Tapatalk 2

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