Input on ways of auditing/handling (PanelView) HMI setpoint changes

Ignition
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1

I have a customer specified project of auditing HMI machine set point changes, from several different Panel View operator interfaces. The values themselves are in PLC tags, written to/read from the Panel View. I'd rather not modify the Panel View program(s) and keep functionality in Ignition if I can. The deviations are variable, could change, so I can't store as constants in the PanelView program.

The auditing to do: Do not allow setpoint changes beyond a min and max deviation, which could vary per different setpoint value... (min / max both of 10, can't change setpoint of 100 past 110 or below 90)

Currently I am starting using a Client Tag Change Event(s), evaluating which tag it is, reading the deviations allowed, (based on the tag path as a key), and evaluating newValue against previousValue.value and the deviation allowed. If it's not allowed, then I write the OldVal back to the tag (writeBlocking). This obviously fires the tag change event again, so I am looking to combat this by saving the last valid value, comparing and not doing the deviation comparison and tag write infinite times (ending recursion :slight_smile: ).
I'm just getting started and looking for the best way programmatically, as I might not be seeing or missing something. Is there a way of stopping or resetting the change in a tag change event, probably not since the change is already done I assume? Thanks much as always.

2

These won't run without a Vision client open. Any changes on the PV while Vision is closed will escape your scrutiny.

Consider writing a gateway timer event that simply checks everything on a repeating basis.

3

I feel this type of setpoint limiting should be handled in the PLC, not just the SCADA/HMI. Depends on what they're controlling

3 Likes
4

Yes, these are various equipment setpoints for aluminum extrusion heating/handling as part of that process.

5

This, of course, relies on you being able to read the recipe setpoint and not just the current setpoint. Otherwise I could change from 100°C to 108°C to 116°C to 124°C without exceeding the ±10°C deviation limit in any one adjustment.