hasChanged(value[, includeQuality][, pollRate] )
object value - The number value to check for change
bool includeQuality - Optional. A flag that indicates if a quality change will also trigger this tag.
The following feature is new in Ignition version 8.0.4
to check out the other new features
int pollRate - Optional. The poll rate in milliseconds. Only applicable on Expression Tags when the Execution Mode is set to Event Driven. All other Execution Modes will ignore this parameter.
The pollRate argument was not present in Ignition 7, but is required in Ignition 8.0.4 for Event Driven Expression Tags. This means that any Expression Tags that are in the Event Driven Execution Mode will either need to have the Execution Mode changed or the poll rate added in on upgrade to 8.0.4, or the function will run once when the value changes and then will not work properly again.
bool - True if the value has changed since the last time the expression was evaluated, False if not.