Deleting BACnet objects from an Enterprise or Automation Server can also remove those objects from the 3rd party BACnet device.

Issue

Deleting BACnet objects from an Enterprise or Automation Server can also remove those objects from the 3rd party BACnet device.

Product Line

SmartStruxure Solution

Environment

StruxureWare Building Operation

3rd Party BACnet Controllers

Cause

The 3rd party controllers in question supported BACnet create and delete services. StruxureWare Building Operation supports both as well, this is different to some of our other product lines that do support these services on 3rd party controllers.

Resolution

Functions as Designed

The delete behavior is designed to function this way. The basic design is that the Building Operation server database should provide as much as possible a complete and accurate image of the contents of the device. So, creating new objects will automatically send a create-object request, and deleting an object will attempt to delete it in the device.

Also, using the "upload" and "download" commands attempts to synchronize the database with the actual contents of the device. Download will attempt to create any objects that are in the database (but not in the device), and attempt to delete any objects from the device which are not in the database. Upload adds or removes from the Building Operation server database.

 

Offline Workaround

You can work around the design by making changes to the database while the device is offline. If the device supports the dcc-disable service, you could set it disabled, and then open the property grid for the device. It should take about 12 seconds and then be reported as offline. Just remember to send the dcc-enable when done. Any other break in communication should also work to get the device offline.

Once offline, objects can be deleted from the database without effecting the device. But, after changing the database this way, you should not use the device's "upload" or "download" commands, as it will re-synchronize the device and database (either deleting objects from the device, or adding them back to the database).