OPC DA interface to read data for advise and polled tags at startup
If digital tags are part of advise groups and the flag to write "Intf Shut" is enabled in the OPC DA interface, then digital tags can read "Intf Shut" for hours/days/weeks, if the value does not change after an interface restart (for example, 2 pumps on the same duty, and they are only swapped every 2-3weeks). The unused pump reads "intf Shut" until it is started.
It would be better for the OPC interface to get new values for ALL tags after a restart, regardless of whether the value has stayed the same before and after the restart, and timestamp them with the restart time.
I have tried to deselect the flag for write status on shutdown but it doesn't seem to work for all tags. I then have to manually edit all the non-reading tags to force a tag update on the interface, which forces it to get a new data value.
I could put digital tags into polled scan classes, but we use 1 second update rates (+1500 digital tags) and timing is critical as part of our production process review.