String tag alarm not executing

Ignition
1

I am trying to alarm a STRING tag. The string will contain an error message, generated when a script creates an Exception error.

The Alarm is supposed to execute On Condition with the following binding on “Is Active”:

{Value}!= ""

The tag gets its value written to by an error handling script with a standard

system.tag.write(tagPath, msg)

But for some reason the alarm is not executing when a value is written to it. I can see the STRING value of the tag change in real time, but the alarm is not generated.

If I manually paste some text into the Tag value it seems to execute the alarm though. Is there some sort of scan issue at play here?

2

Have you looked at the tag diagnostics in both cases?

3

in stead of using {Value}!= "" can you use len({Value}) > 0?

4

I have tried this but it doesn't seem to compile. Get an error in the Gateway console saying it failed to compile.

5

Where are the tag diagnostics? If it is in the Designer under Help->Diagnostics, i'm afraid i cant open that panel due to some other strange error.

7

Pasted image754×823 37.1 KB

8

Ah thanks.

Turns out the alarm was working, it just wasn’t showing up on my Alarm Status table which led me on a bit of a wild goose chase…
The use of a wildcard filter (ScriptErrors*) on the Display Path wasn’t working as expected.

Sorry for the wild goose chase, things always seem much easier to figure out after a short break.