I'm trying to get a Last Updated timestamp for a group of analog data points.
This is to try and determine the last time that a device was seen. There isn't currently a field available in the base MQTT driver that allows me to just check that the device, and analog points within have actually received data. The healthy flag is set as long as the topic subscription is successful.
I'm currently trying to use the Calculation Time Point. But this doesn't allow for a wild card selection (ie ".$.CurrentTime") for the expression.
Ideally this would update as soon as any data is received into an Analog point in the group containing the my MQTT data points.
Re: Last Updated Time for a group of Analog Points
Simple Expressions do not support 'wildcards'. They must be entirely resolvable at "save-time".
You could use some ST logic to do this, with some SQL.
I'd probably use the Query Processor MAX() / MIN() aggregates to find the oldest / newest data timestamp as required.
For convenience at a latter time you could request some DataPointTimestamp property on Scanners / Outstations to hold such a value. I think it has been requested offline before, but not in the new Exchange Features section (worth a search of the Exchange for it anyway). If you create it, I'll upvote it.
Lead Control Systems Engineer for Alliance Automation (VIC). All opinions are my own and do not represent the opinions or policies of my employer, or of my cat..