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  1. #1
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    Dec 2014
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    Post JCI BACnet MS/TP MAC Address 1-3 Reserved

    Does anyone know why JCI says we cannot use MAC addresses 1 to 3 with their products? What are they reserving this for? I've never seen a rule like this on any other BACnet products I've worked with. Does this just apply to their products, or will there be issues if I connect my (non-JCI) device and address it in that range.

    It's in this tech doc on page 19, but they don't make it clear why they have this rule.

    JCI MSTP Tech Doc.pdf

  2. #2
    Join Date
    Sep 2013
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    You can connect other devices at MAC 2 and 3. The Bluetooth commissioning tool has a instance number of 1 (which maybe why it was reserved). I’ve talked to techs who brought in other devices and I believe they had to change the address of MAC 1 but not two and three.

    I think it was there for future functionality like a display.

    @Jciman would know better the reasoning.

  3. #3
    Join Date
    Jan 2015
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    They are "theoretically" reserved for utility tools and front end controllers.

  4. #4
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    Jun 2009
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    StL, MO
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    Having those addresses in use dealt me a fit one time.
    https://hvac-talk.com/vbb/showthread.php?1842311
    UA LU 562

  5. #5
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    Dec 2006
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    I never use 1-3 on MSTP no matter what brand. Have been told "tools" use those addresses. Easy enough not to use them.

  6. #6
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    Thread Starter
    Interesting, thanks for the info. We don't see much JCI stuff in our area so maybe that's why I haven't encountered this issue yet.

  7. #7
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    Mar 2008
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    Council Bluffs, Iowa
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    I have alwyas started my addressing at MAC 5. One basic reason is that any new software configurable controller that gets added will ususally come out of the box lower than that, and will be accessible for proper configuration(If not done by dip switches). No gaps after that though.

  8. #8
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    I guess I don't use tools like that much. I generally reserve 0 for routers but will start numbering field devices at 1 and never had issue.
    Scott Jalbert
    WebCTRL ninja
    AX and Smartstruxure newb

    The S in IoT stands for Security

  9. #9
    Join Date
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    I think, after reading some of the JCI documentation about some of their canned systems, like verasys, etc, you will see some of their mstp devices auto bind to some of those lower addresses for reporting/voting calculations, etc., because the main brain controllers/devices take those spots, I assume that could be a reason why they mention to leave those addresses alone. cheers.

  10. #10
    Join Date
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    Quote Originally Posted by CB_Matt View Post
    I have alwyas started my addressing at MAC 5. One basic reason is that any new software configurable controller that gets added will ususally come out of the box lower than that, and will be accessible for proper configuration(If not done by dip switches). No gaps after that though.
    I feel like it should start at 5, especially when putting in TEC3000’s they come online with a mac of 4 and instance of 1 at default.


    Sent from my iPhone using Tapatalk

  11. #11
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    Dec 2014
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    Thread Starter
    Quote Originally Posted by MaxBurn View Post
    I guess I don't use tools like that much. I generally reserve 0 for routers but will start numbering field devices at 1 and never had issue.
    Yeah that's the same experience I've had. I work with Delta Controls, but I've integrated with lots of other vendors too. We always start at 1 and go up from there avoiding gaps. Routers are usually 0, occasionally 100.

    This is the first time I've seen a rule like this, or a tool that cannot adjust its mac address.

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