Bind the Quality property of a component to an expression

General Discussion
1

Is it possible to bind a component’s Quality property to another tag using an expression?

I have 2 tags

  • Tag1 (Float)
  • Tag1_Quality (Float, 0=Good, 1=Bad)

Can the tag Tag1_Quality drive the quality of Tag1 ?

When I use the expression to
ToInt({[default]PLC-1/Tag1_Quality})

I get the error:
ClassCastException: Cannot coerce value '1' into type: class com.inductiveautomation.ignition.common.model.values.QualityCode

I am using Ignition 8.0.1

Thank you,

-Mark

2

The quality of a tag is automatically determined by its value property - what you would need to do is make Tag1 an expression tag, and use the (new to 8.0) qualifiedValue expression to do something like this:
qualifiedValue(<expression to retrieve actual value for tag>, <expression to return "Good" or "Bad">)
where the second argument is something like if({Tag1_Quality}, "Good", "Bad").

3

Ok used your suggestion and it kind of works.
The quality state is updating correctly, however the overlay is not reflecting the quality state.
I have the option “Overlay Opt-Out:” turned off. So perhaps this is a bug ?

I observed:

  • If “Overlay Opt-Out” is OFF, propertychange event handler is executed when a change to Tag1_Quality occurs
  • If “Overlay Opt-Out” is OFF, propertychagne event handler is NOT executed when a change to Tag1_Quality occurs

Here is a workaround using script

if Tag1_Quality changes, update Tag1 quality.

Tag1_Quality propertychange event handler

from com.inductiveautomation.ignition.common.model.values import QualityCode

if (event.propertyName == "state"):
#	print event.propertyName, " ", event.newValue
	if (event.newValue == 0):
		event.source.parent.getComponent('_').quality = QualityCode.Good
	else:
		event.source.parent.getComponent('_').quality = QualityCode.Bad

I also observed that if Tag1 updates, it replaces its quality with a new one.

So you also need
Tag1 propertychange event handler

from com.inductiveautomation.ignition.common.model.values import QualityCode

print event.propertyName, event.oldValue, event.newValue

if (event.propertyName == "dataQuality"):
	BQ_val = event.source.parent.getComponent('BQ').indicatorValue
	if (BQ_val == 0):
		BQ_quality = QualityCode.Good
	else:
		BQ_quality = QualityCode.Bad

	if (event.source.quality  !=  BQ_quality):
		event.source.quality = BQ_quality

Let me know if you can get the expression binding working as it is a lot cleaner solution.

Thank you