Sure, “ACK Sync” sounds cool, but what is it, exactly? In simplest terms, it’s a way to make sure WIN-911 and the SCADA providing the OPC server are in agreement on an alarm’s acknowledgement state.


    OPC Data Access has no concept of “alarms” or “acknowledgement”. All it does is hand over values. WIN-911, in this case, handles the alarms and acknowledgment of those alarms. If your SCADA is acting as an OPC server, then it probably also handles the OPC alarms and acknowledgements. Since WIN-911 isn’t talking to the SCADA directly, if you use it to acknowledge an alarm, the SCADA won’t know about it. Conversely, if you use the SCADA to acknowledge an alarm, WIN-911 won’t know about it.


    That’s where ACK Sync steps in. If the SCADA you’re using uses a tag that keeps track of an alarm’s acknowledgement state, then WIN-911 can read from that tag to see if the SCADA was used to acknowledge an alarm. WIN-911 can then treat that alarm as acknowledged.


    If WIN-911 acknowledges the alarm, it can write the acknowledgement to the Ack Sync Write tag with the value that the SCADA expects for true, and the SCADA will know the alarm has been acknowledged.


    On the other hand, if WIN-911 wants to know if an alarm has been acknowledged, it can check the tag in the Ack Sync Read field.