I am using UDTs with expression and OPC tags (Ignition 8.0.7). The issue I have encounter is that eventhough all tags belong to a direct mode tag group with rate at 5sec those OPC tags that are used in expressions are scanned (subscribed) at 1 sec. The behaviour can be replicated even without udts by just adding an expression tag that uses a simulated tag from the internal opc server and then restarting the opc tag. It seems that when opc tags are involved in expressions their scan rate is not respected and I am wondering if this is normal or something crucial skipped my attention.
I’m pretty sure this is related to a bug that has been fixed and will be available in a nightly release later this week.
Same as this one: Modbus TCP uncontrolled polling
Confusingly, the fix is available in the current 8.0.9 nightly release, but there is a “hot fix” 8.0.9 release coming today that will not actually include it. The next nightly release that includes it will be for 8.0.10.
Thanks Kevin I am pretty sure that lot of udt users will appreciate it as it is can drastically affect the performance on a system.