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BacNet points not working as expected?

  • So I'm working on a trial mango install at an existing site (currently running Alerton Envision 2.6), with mostly Alerton hardware. Upon setting up the BacNet datasouce, and enabling it, it sends out a who-is, and gets back responses from only 4 devices, 3 of them the York chillers, connected via MS/TP from an Alerton BCM that doesn't respond.

    Anyway, regardless of the lack of response the rest of the massive site is giving me, which I'll look into later, I'm wondering about how point setup should be done. Lets say, for example, i want to set up AV-8409 on a BacNet/IP device (instance 430). I set the point up as follows:
    NAME: 430_AV-8409
    Network: 0
    MAC: 430
    Device instance: 430
    type: AV
    object instance 8409
    Use COV: unchecked

    When doing this, it never polls the point - in fact, it never even sends out a who-is to find device 430. If I set up a point that is on one of the devices that DID successfully respond to the initial who-is, it works. Is this a limitation of the bacnet implementation? If it doesn't already have an idea of how to find a given device, shouldn't it ask?

    I am running the mango server on ubuntu inside a virtualbox vm, and monitoring the traffic with Wireshark on the windows host.

  • No response on this call for help?

  • The version of Mango you are using does not send WhoIs to find devices. It expects to be configured to find them without WhoIs. (Except for the discovery tool, of course.)

  • @mlohbihler said:

    The version of Mango you are using does not send WhoIs to find devices. It expects to be configured to find them without WhoIs. (Except for the discovery tool, of course.)
    Actually, this looks related to my other post. It looks like, when starting up, mango DOES send out an undirected who-is - but since it is not seeing the broadcasted i-am's, it is still unable to route to the appropriate link. On the devices that DO respond directly the the source of the who-is, it then requests some capabilities - but it still won't actually poll a point using the device instance and object alone (which it really SHOULD be able to do). I wouldn't think you'd need to set up network numbers, MAC addresses and link service IP, unless specifically needed by network topology. That information should be able to be obtained via basic bacnet who-is requests and i-am responses.

    My concern, is that by having to specify the link service IP and MAC address, you eliminate the REASON for bacnet having a device instance number (meaning a specific name for a given piece of equipment, regardless of network topology to get there). BACNet should be immune to issues involving IP changes and such, and should always be able to find a given device by instance number alone.

    The way i would like to see it done:
    If a point's details include network/MAC/link service IP, it will use them. However, if left blank, then on enabling of the point, it will perform a who-is on that device, and fill in the missing data in the dynamic online database, and use that going forward for communication with that device. It will not, however, write that information to the stored database, as next time that point/data source is enabled, it may very well be different.

  • What version of Mango and BACnet are you using?


  • Not at work currently, but just re-downloaded/installed them Monday, so judging by the web site, I'd recon core-2.1.0 and bacnet 2.0.3.