Gateway Script Tag Issue

Ignition
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1

I have the following gateway script:

def dura(tagPath,box):
	tag = system.tag.readBlocking(tagPath)
	if tag == 2:
		box.props.value = tag
	else:
		box.props.value = 0

Very simple script, if the tags value is equal to 2, then display 2 in a numeric entry field.

Then in my project, I have a button with the following script:

	startTime = "[default]Timesheet/startTime"
	box = self.getSibling("startTime1")
	message.dura(startTime,box)

startTime is the tag that is being read in the gateway script and box is the numeric entry field where the value 2 should be displayed.

Currently, the tag does have a value if 2. So, in theory, a value of 2 should be displayed.. but a 0 is being displayed. I can read the tag in correctly in the gateway script, but every time I use the tag in a conditional statement, it seems as if the value isn't being read..

I tried to just use the value attribute of the tag, but I get an error saying

'str' object has no attribute 'value'

Thank you in advance.

2

tag = system.tag.readBlocking(tagPath)[0].value

3

Added this and am still getting the same result

4

You need to do some hunting then. Try logging the value and type of tag before the comparison.

Add something like:

# If you're running in a gateway context, this should show up on the webpage log viewer.
_logger = system.util.getLogger('script debug')
_logger.info(tag)
_logger.info(type(tag))
5

You said gateway script, but you’re trying to interact with components. Exactly where is this script defined?

1 Like
6

image

Here is where the script resides.

The script is called when a button is clicked in my project.

7

Okay, that makes more sense.

Given that, I would expect this variation of your original script to work:

def dura(tagPath,box):
	tag = system.tag.readBlocking(tagPath)[0].value
	if tag == 2:
		box.props.value = tag
	else:
		box.props.value = 0

What error are you getting from that, if any?

8

I am not receiving an error, the problem is that the conditional statement is returning a 0 when the value of the tag is, in fact, 2. So, the conditional statement should return a 2, rather than a 0.

9

I would then echo @zacht’s suggestion to log the data type of the value; perhaps it’s a string when you’re comparing it against an int? Python won’t do any automatic type coercion.

2 Likes
10

Got it, had to change it to an int.

1 Like