Gateway Tag Change Scripts Periodically missing tag change events

Ignition
1

Hi All,

We have some gateway tag change scripts that are periodically missing tag change events. In an attempt to mitigate stale tag values we are using the following method to trigger data processing in the gateway script. We use an integer for the trigger for the script, plc sets it to value 1 when data is available, gateway change script then changes it to 3, plc then immediately changes it to 7. Once gateway tag change script sees a 7 if processes the data as needed. We are seeing some sporadic but fairly repeatable instances where data change is missed. Is there a better way?

Ignition 8.0.12

Thanks,

Frank

2

Don’t change tags from two directions. Let the PLC set a trigger, then have Ignition set a different tag to acknowledge. PLC leaves trigger until acknowledged. For more robustness, use short integers as your triggers (incrementing with rollover to trigger), and echo that integer from Ignition as your acknowledge. With integers like this, instead of using initialChange to filter out project restarts, simply check that the trigger is different from the echo at the start.