UDT tag Scripting

Ignition
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21

readBlocking always returns a list of QualifiedValues.

writeBlocking will accept a QualifiedValue.

Probably also want to filter initialChange

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22

Hmm, at this point I'd just throw out all assumptions and build this up slowly. Try one line of code that writes a static value to a full tag path. If that works, write it to an indirect tag path. If that works, add an if statement, etc. When a step doesn't work, you should have an idea of what's going wrong.

I'm wondering if the if statement is evaluating to false. Can't check that on my end, but I tried building a similar setup from the information I see here and it seems to be working fine.

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This is the Value Changed script on ReadTag:

def valueChanged(tag, tagPath, previousValue, currentValue, initialChange, missedEvents):
	value = system.tag.readBlocking("[.]ReadTag")
	system.tag.writeBlocking("[.]Folder/WriteTag", value)
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23

[~] means "change tag's tag provider". To use relative referencing you should be using [.]

https://docs.inductiveautomation.com/display/DOC81/Tag+Paths

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image1430×258 10.9 KB

Edit: perhaps I missed that you'd already changed this...

24

the only difference I see with what it it that I am using a tag external to the UDT where as yours is all internal the the UDT. I will try something like that.

25

So I have found that if my IF or whatever I want to use is in the UDT it executes but if I use anything that exists outside of the UDT it doesnt execute. I can make that work, I think.

Thank for the help guys!

26

Glad you're making progress, though you should be able to reference outside tags if you want to.

I created an AlwaysTrue tag in the same root directory as the UDT instance and can access it no problem.

def valueChanged(tag, tagPath, previousValue, currentValue, initialChange, missedEvents):
	if system.tag.readBlocking("[.]../AlwaysTrue")[0].value:
		value = system.tag.readBlocking("[.]ReadTag")
		system.tag.writeBlocking("[.]Folder/WriteTag", value)

It also works when I use an absolute path.

	if system.tag.readBlocking("[Sample_Tags]AlwaysTrue")[0].value:
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