Starting at v1.2.7 of Events2HVAC, you have the ability to send the current active event name for a zone to a BACnet object's description property for display purposes on the BACnet system. With this feature, you can inform users of the HVAC system what event is controlling the room occupancy.
For this example we have a zone that is currently controlling a VAV box. We want to write to a BACnet object's description to indicate the current active event in the zone. We could write to the same object that is controlling the VAV box or we could create a new BACnet object for the purposes of displaying the description (recommended). In this example we going to use the same BACnet object for the room control and the description. Here's what the original zone actions look like:
Here's the steps to correctly setting up the actions and triggers required to display each event new event in a equipment zone:
Note: Implementing the WriteDescription feature will generate additional command loads on your server.
Create a WriteDescription Action for Each Event Start Trigger
This action will update the description on the BACnet object every time a new event is started for a zone.
1. For the zone that you want to write the description, create a new action using the WriteDescription action. This action will trigger at each event's start time. For the start value of the action, use the token [EventName] to grab the event name that triggered the start.
2. Since every BACnet device and it's object may have different limits on the length of the description property, you should modify the "Max Length" value of the action to be less than the BACnet limit for the point you are writing to. If you exceed the limit in the BACnet object, you will get an error when you try to write the description. You can enter some test text in the start value and hit the "Test Start" button to send the data to BACnet. You can use this method to determine what the maximum length value will be needed. If an event's description exceeds the max length property it will be truncated so that it will not generated an error on the BACnet command.
Note: when you use a single trigger like Event Start, the pre-start and post-stop times in the equipment definition are not used
Create a WriteDescription Action for the Event's Start/Stop Period
In order to properly signal the end of each event you will need to create another action using the Event Start/Stop trigger. Use the same parameters as the single event start trigger above, but this action will also allow you to set the description at the end of an event. The default value is "No Event Scheduled".
1. Create a new action with the triggering event as Event Start/Stop or Event Setup/Teardown (Dual action events). This action will trigger at each event's aggregated* start time and stop time. For the start value of the action, use the token [EventName] to grab the event name that triggered the start. For the Stop value, enter a description that would display if there is no event scheduled.
*Aggregated start/stop means that all schedules for the zone are combined before evaluating the start and stop times.
2. Verify the point can be verified and written to using both start and stop commands.
Note: The pre-start and post-stop times in the equipment definition will affect when the description is written. If you do not want your equipment pre-start/post-stop times to be applied to the description action, you will need to create a separate zone just for the WriteDescription actions.
Here's what the actions for the zone looks like after implementing the WriteDescription actions:
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