Values from points in BACnet devices do not update in Graphics, Watch window etc but show correct value when the point is opened.

Issue

Values from points in BACnet devices on the MSTP do not update in Graphics, Watch window etc but show correct value when the point is opened.

Product Line

SmartStruxure Solution

Environment

Automation Server - AS

BACnet Interface

BACnet Devices

Cause

Time not synchronized between devices.

BACnet COVs depend heavily on time for correct operation, when time drifts between the devices COV will stop updating, the point shows the correct value when opened because in that case a read property is used instead of COV.

Resolution

Make sure time is properly synchronized between ES, AS and all BACnet devices.

See Lessons Learned Article #7803 and Lessons Learned Article #12680 on the subject.