Events2HVAC Blog

New Feature: BACnet Exception Schedules

Oct 2

Written by:
10/2/2017 12:22 PM  RssIcon

Events2HVAC can now send 24 hours of exception schedules to a BACnet schedule object rather than sending occupied/unoccupied commands to a BACnet binary value object.

What does this mean to you?

The traditional way Events2HVAC functions is to queue up 24 hours of schedules in its local database, and send out occupied and unoccupied commands at the appropriate times for each individual event. All Events2HVAC implementations to date have used this very reliable method of automation.

But if you are using a BAS that is BACnet- enabled, you now have a different option. You can choose to send 24 hours of schedules to your BAS as exception schedules, which provides a few advantages:

  • If communication is lost between Events2HVAC and your BAS, the BAS will still have 24 hours of schedules, minus however long it has been since the last poll cycle.
  • If your BAS has optimal start capabilities, you can send exception schedules with Events2HVAC, and use the optimal start logic in your BAS to start the system based on the weather, eliminating the need to set pre-start times in Events2HVAC.
  • Your HVAC operator will be able see 24 hours of future schedules in the BAS without logging into another system.
  • Pushing schedules instead of queuing up 24 hours of binary state changes will actually reduce the overall command queue processing load on your server.

Of course, there is also a downside:

  • Since Events2HVAC is sending a schedule rather than an occupied or unoccupied state, there is no re-sync – it will not retry if there is a failure. Events2HVAC will send the schedules once. If they are not received, it will not send them again until the next poll cycle. Typically poll cycles are set every hour, so with 24 hours of schedules this shouldn’t be a big problem. But it is a difference to consider.
  • Sending 24 hours of schedules every poll cycle will put a bigger instantaneous load on the system if you are sending to several hundred individual zones. Therefore, it is best to use this method only for the zones that need it (i.e. large auditoriums, OST zones, etc.), rather than setting up an entire campus up this way.

For details on how to set up this preview feature in Events2HVAC, please see the SendExceptionSchedule Action page in the Events2HVAC online help manual.

Automated Logic Add-on

The motivation behind the BACnet exception schedules feature of Events2HVAC came from Stephen Durfee, Campus Energy Manager at Bucknell University. Durfee has been using Events2HVAC for several years, but wanted to take advantage of optimal start capabilities in his BAS, Automated Logic.

While testing the new feature on site at Bucknell, we discovered that Automated Logic did not recognize the BACnet exception schedules properly. So, Durfee contacted Automated Logic and convinced them to develop an add-on that would accept exception schedules sent via BACnet/IP.

The Automated Logic BACnet Scheduling Add-on is currently being tested at Bucknell University, and Durfee reports that it is working great.

Automated Logic has determined that using their BACnet Scheduling Add-on requires:

  • You are running a v6.5 system with the latest cumulative patch applied
  • You have downloaded bacnetscheduling.addon
  • The system is configured with at least one active BACnet IP connection.
  • You have purchased and downloaded the BACnet Scheduling license
  • You have adequate disk space available to store the add-on's data.
  • Your system is backed up regularly to ensure the add-on's data is also backed up.

For more information on the add-on, please contact your Automated Logic representative.

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Phone: (888) 320-4277



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