Process variables which can be mapped to standard BACnet objects are COV-capable.
I/O function block
Function blocks for Analog, Binary and Multistate Inputs, Outputs and Values are mapped directly to the associated BACnet object types. They are COV-capable and can establish COV connections with all COV clients.
Interface variables
Interface variables of compounds and function blocks whose data type is Analog, Binary, Multistate, Integer, Duration and DateTime are COV-capable and can be mapped to simplified BACnet value objects for operation and monitoring.
A COV is initiated when the value of the process variable [PrVal] of the BACnet object which represents it changes. A COV is also initiated when a status flag [StaFlg] (InAlarm, Fault, Overridden or Out of service) changes, e.g., when a sensor open circuit (fault) occurs or when an I/O value is overwritten manually.
COV increment
For analog objects, a COV is not initiated for every minor change of [PrVal], but only when the value changes by an amount greater than a predefined increment. This increment is saved in the COV increment [COV] of the analog object, and can be defined in Xworks Plus (XWP) during engineering.