3 Replies Latest reply on Feb 5, 2018 6:34 PM by gmichaud-verreault

    BACnet interface not scanning as frequently as it should


      I am monitoring pump statuses that can run for as little a few seconds, but as starting point, I've set their scan class to be 15 seconds. Here's the archive values for a pump tag in PI:


      The timestamps in yellow are instances where I restarted the interface, essentially forcing a value to come through.


      Here are the actual values, which I'm able to see in a SQL table:

      The highlighted instances are where the pump was "on" for at least 15 seconds, meaning the tag should have picked up the change.


      As far as config goes, the scan class options for the Interface and the tag's location 4 line up:



      What could be wrong?


        • Re: BACnet interface not scanning as frequently as it should

          Hi Kelsey,


          First off, I would make sure that you do not have any scans skipped. Next up, I would suggest setting up debugging. You can either use /BACnetDbg=0x0002, which will log all decoded BACnet responses from the Device, or even better set up a Wireshark trace with the BACnet filter to see where it went wrong.


          Alternatively, if the device supports COV (Change of Value), then it may be a better option to make sure you don't miss any event. With COV, the interface subscribes to the device for Change of Value and the device only sends data updates when the change of value has exceeded the specified COVIncrement parameter.






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            • Re: BACnet interface not scanning as frequently as it should

              Hi Gabriel,


              Thank you for your reply and your suggestions. My scan class is now every 5 seconds, which seemed to help some other tags. However, a tag I've been monitoring had an event this morning that was not picked up:

              BACnet tag                                                                                     Data from SQL table:



              My interface does seem to be skipping scans (e.g., at 9:01:52 and 9:01:57):

              However, the scan classes skipped tag hasn't had any new values since 1/26:


              I tried to use Wireshark as well as YABE, but only select IP Addresses can be seen.


              As for COV, I've tried to configure a few different types of tags but no data came through, so I'm not sure where to go from here.