Propagate timestamps with alarms and events

An alarm feature always registers a reference to the alarmed attribute. This registered reference guarantees that Message Exchange never suspends updates for the alarmed attribute. Even if alarms are disabled for a particular attribute, the Advanced Communication Management feature cannot suspend the attribute.

Be aware that the time stamp propagates to all masked bits of an integer attribute, even if only one of the bits changes.

For example, you have an Integer address in a PLC that represents 16 different alarm states. You assign ObjA.Attr_Integer to point to the PLC address. You then split the bits to different alarm attributes, adding one attribute for each alarm and naming them ObjA.Attr_Alarm00 to ObjA.Attr_Alarm15. Each attribute has an input source that refers to a different bit of ObjA.Attr_Integer. For example, ObjA.Attr_00.InputSource -> me.Attr_Int.00, and so on. At runtime, when bit 00 is changing in the PLC, all of the attributes (ObjA.Attr_Alarm00 to ObjA.Attr_Alarm15) get a new time stamp, as all the bits changed. This can cause incorrect time stamps for alarms.