I’d like to send an email when the gateway loses comms to a device. The sending of the email is no problem, however, I’m not sure what would be the best way to determine the state of communications to a device. Should I interrogate the quality of an existing tag (and if so how?) or is there a way to test the status of the device itself? In any case, I figure I’d write a timer script that would do the test periodically. Thanks for any help.
Kurt
You could write a gateway tag-change script that was bound to the Quality property of a tag on the device, so that you could be notified directly when the quality become poor, which would be a good indicator of comms.
Thanks, that worked fine, maybe too fine. One day I started getting inundated with emails. Apparently the quality value was going from good to stale and back repeatedly. Network traffic related maybe. Anyway, the scan class for the tag had a Slow Rate of 1,000 and a Stale Timeout value of 10,000. I was able to stop the quality value from changing by changing the Slow Rate value to 5,000. I would have thought the Stale Timeout value would have affected this.
No, the stale timeout setting is only used for database-driving providers. You are most likely using the internal provider where your tags are stored in Ignition. In that case there is a setting in the Gateway Configuration section under OPC-UA > Settings called Stale Threshold. By default the setting is 2.5, which means that if don’t receive values back from the OPC server in 2.5 X scan class rate your tags will go stale.
For example, if your scan class rate is 1 second your tags could be stale if we don’t receive anything in 2.5 seconds (2.5 X 1 s). By increasing your slow rate you are giving the OPC server more time to complete the request which is 2.5 X 5 = 12.5 seconds.