Hello folks,
greenhorn here,
I have been working on these Performance Equations for the past few weeks, and believe the math to be solid. Here's a typical one:
IF (( (TagVal('PH_VSTATUS_SIM')) And 2) = 2) THEN 1 ELSE 0
PH_VSTATUS_SIM is a normal tag incoming from PLC, sends us a 16 bit integer register, where each bit carries different meanings, so above equation uses bitmask-bitwise-and method to extract info regarding the second spot in that 16bit register.
When I click Evaluate button in Equation Tab, the result box shows the expected values for the various inputs on 'PH_VSTATUS_SIM' tried.
That Rocks. It's good.
What makes me sad is below that, the "Snapshot:" line with Timestamp and Value. It reads 0 always, irrespective of any input change.
What's puzzling is that looking at it from Current Values under the Data SMT node, and the Archive Editor view shows a history of value 0... a couple of events triggered at same time it should have written a 1 in there. Now I am supposed to build upon these booleans for more complex PE Tags, and until these are reliable I am stuck.
Could you kindly point me in the right direction regarding these PE-tag-point configurations?
Why would the Evaluate value be one thing and the Snapshot Value going to Archive be another? How is that possible?
Here's what I've tried so far:
- Changed Scheduling from every 1 second (Scan class) to Event based, dependent upon Event tag: 'PH_VSTATUS_SIM'
- Turned off compression altogether
- Changed timestamp from "from triggering event" to "evaluation time" and back.
- Changed Exception Deviation to 0, with min and max times to 0.
- In Archive tab, Typical value is set to 0, Zero is set to 0, and Span is set to 2.
What am I missing here?
Many thanks in advance,
-h