How to read UDT instance parameter values from a script (Ignition 8.3)

Ignition
,
1

I would like to get the parameter values set on each UDT instance using a script.

Environment

  • Ignition 8.3.0 (b2025091510)
  • Run in a Perspective transform and in the Script Console

I tried the following, but could not get the data. How can I get these values with a script?

  1. system.tag.getConfiguration
  2. system.tag.readBlocking([instancePath + ".Parameters"])[0].value
  3. system.tag.browse(instancePath + "/Parameters").getResults()
2

If you want to do this via system.tag.readBlocking, you have to know the name of the parameter you're trying to read.

system.tag.readBlocking([instancePath + "/Parameters.myParam"])[0].value

Note the .myParam in my example above.

.getConfiguration should also give you the param values, but I think it will only give you the overriden parameters (not tested), not true, you can get the parameters via the parameters key, even the ones not overriden.

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image1444×136 10 KB

Never tried .browse to read parameter values, but I don't think this works.

3

Hello,

Just putting this here as it related to parameter access. You can also access the parameters in a tag event script as well via:

def valueChanged(tag, tagPath, previousValue, currentValue, initialChange, missedEvents):
    tag["parameters"]["myParam"]
4

You can do this with readblocking.

However, something to consider - there are many times that I need to display the parameters of and instance in a template that is built for that UDT. I have made it a habit of having a "param" folder in every UDT that simply has one tag for every parameter and binds to each one. Then you just read/bind it like any other tag.

5

Why that over an indirect binding directly to the parameter?

6

No real reason I can remember atm. I don't recall if the parameters show up in the tag binding selection dialog or not