Do Expression tags always lease OPC tags if they themselves are leased?

Ignition
1

First, I apologize if this is covered somewhere, but my search only revealed a 12-year-old post that wasn't exactly the scenario I was wondering about.

I know that an expression tag counts as a "lease" if it references an OPC tag in a leased tag group.

So here's the Scenario I'm curious about:

Let's say I have a UDT in ignition. One of my elements is an OPC tag. The other is an Expression tag. The expression tag uses the result of the OPC tag in its calculation. On a perspective view, I reference the expression tag. I set both the OPC tag and the Expression tag to a leased tag group, and I set the Expression tag's execution mode to "Tag Group."

Given all that, does that mean the OPC driver will only read the OPC tag at the leased rate when I have that view open in a session, because the expression tag that I'm actually binding to is in the same leased group and the execution mode is "tag group?" Conversely, when that view isn't open in any sessions, does the expression run at the base rate, therefore only calling for the OPC tag at the base rate?

2

From my testing, expression tags will lease OPC tags regardless of whether the expression tag itself is leased or not. As long as the OPC tag is referenced somewhere in a tag expression and the tag is enabled, the OPC tag will stay leased forever and never use the base rate. This is a bit of a problem because it destroys our logix driver performance.

I’d be interested to see if anyone has an alternative for this, the only thing I can think of is using a tag change script and a memory tag instead of an expression, but that has its own problems.