Hi.
I have this real value that has 15 decimals (unfortanely).
I wish to update a textbox with this real value, but round it down to 2-3 decimals and att “mbar” in the end.
I have tried the propertyChange with:
event.source.text = system.tag.readBlocking(["[default]zB1ADFilter/MovAvg.value)"]) + " mbar"
But this does not seem to work, adding round to the tag causes an error that round is not defined etc.
Perhaps there is a better way to do this other than propertyChange on the textbox?
Use an expression and use numberFormat({value}, '0.000') + ' mBar'
I tried this:
event.source.text = numberFormat(system.tag.readBlocking(["[default]zB1ADFilter/MovAvg.value)"]), ‘0.000’) + " mbar"
But the error i get is numberFormat is undefined:
Traceback (most recent call last):
File "<event:propertyChange>", line 1, in <module>
NameError: name 'numberFormat' is not defined
Ignition v8.1.10 (b2021090812)
Java: Azul Systems, Inc. 11.0.11
And , the return object of system.tag.readBlocking is a list, try:
event.source.text = str(round(system.tag.readBlocking(["[default]zB1ADFilter/MovAvg.value)"])[0].value,2)) + " mbar"
@SKA, just as an aside, when you start a thread, it’s good to know what version of Ignition you’re using, and whether it’s vision or perspective, as the answers so far have already gone into the weeds with both. 
Bind the text property to an expression, using the one @nminchin supplied.
I use V8.1.10 + Vision module, not perspective.
My text field does not have expression what i can see, only scripting and does not look anything like the image @nideyijuyidong posted.
Sorry, I never used Vision… 
This is why it’s useful to state. 
Click on the ‘chain link’ at the Text property.
Choose expression on left side of the dialog box. Expression in your case:
numberFormat({[default]zB1ADFilter/MovAvg}, '0.000') + ' mBar'
Thanks.
After some debugging here and there (compared to example above)
I now got it to show as i wished
