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  1. #1
    Join Date
    Jun 2012
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    Byrant RTU Open Space Setpoints

    I've got a project that consists entirely of RTU open controllers in Bryant rooftops. The boards have lon cards and seem to communicate and run correctly. My issue is that whenever I or the owner changes the NVIs for the space temperature set points inside of AX, the change appears to change for a moment and then change back to the original value. The boards were provided by a mechanical contractor which has no one on staff that knows anything about them. I've looked through the RTU open manual online, including the sequence of operations and have had no luck. Other set points such as the outside air minimum position work correctly. Any thoughts?

  2. #2
    Join Date
    Apr 2014
    Location
    MN
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    I've never really worked on a Lon integration with an RTU Open board, but if you have field assistant you can connect to the boards and check the protocol mapping for the points. In FA, right click the controller and go to driver properties and it's under Communications. It might be those points are not mapped correctly.
    Other than that, I seem to remember that they updated the xif files depending on the version of the RTU Open board. Maybe you've got the old xif and the newer boards?
    Sorry I can't help much more, really don't know Lon.

  3. #3
    Join Date
    Jun 2012
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    Thanks for the info.

    My earlier post was based on a discussion with the owner as I hadn't been on site yet. I'm here right, and the issue is slightly different than the owner claimed. The NVs work for the setpoinits, but there is a minimum of a 5 degree differential between heating and cooling. If you bump the heating setpoint within 3 degrees of the cooling setpoint, the cooling sepoint will go up by 2 degrees to maintain the 5 degree difference. So now I'm trying to figure out what value needs to be changed to allow the sepoints to be closer together.

  4. #4
    Join Date
    Apr 2014
    Location
    MN
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    Look for a minimum setpoint separation value.

  5. #5
    Join Date
    Apr 2014
    Location
    MN
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    In the BACnet side of things it's Minimum Setpoint Separation min_stpt_sep AV:63. And I think it comes out of the factory as non-network visible. I'm not sure how that translates into the Lon side of things, but you might have to use Field Assistant to make the change.

  6. #6
    Join Date
    Jun 2012
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    Quote Originally Posted by bacnet>CCN View Post
    In the BACnet side of things it's Minimum Setpoint Separation min_stpt_sep AV:63. And I think it comes out of the factory as non-network visible. I'm not sure how that translates into the Lon side of things, but you might have to use Field Assistant to make the change.

    Thanks for the insight. I actually have to set the units up for Bacnet to change a few things and then change it to Lon because some of the points don't exist in Lon.

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