Configuring "Is Active" Expression Binding from Script for Alarms

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1

I'm attempting to set the "Is Active" expression binding (below) from a script, when in "Mode" is set to "On Condition".

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I understand the "Is Active" property name is named activeCondition in scripting, however this is a Boolean value, and I can't seem to write an expression written to it. Is there a way to write to the expression binding from a script, similar to the format below, where activeConditionExpression is the scripting name for the "Is Active" expression binding and myExpression is the expression I wish to write to this binding?

alarm = {
    "name": tagName,
    "mode": "OnCondition",
    "activeConditionExpression": myExpression
}
2

I suggest you add an expression normally and then export the tag's json and have a look at what the value of that prop is. You will need to follow suit and use system.tag.configure to write the config change back to the tag. Ensure that you set the mode to merge changes, not to overwrite them.

e.g.
Example tag JSON with manually configured (bogus) expression:
tagpath: [default]System/New Tag

{
  "valueSource": "memory",
  "alarms": [
    {
      "mode": "OnCondition",
      "name": "Alarm",
      "activeCondition": {
        "bindType": "Expression",
        "value": "if({tag}, 5, False)"
      }
    }
  ],
  "name": "New Tag",
  "tagType": "AtomicTag"
}

Script to reconfigure it:

cfg = [{
  "name": "New Tag",
  "alarms": [
    {
      "mode": "OnCondition",
      "name": "Alarm",
      "activeCondition": {
        "bindType": "Expression",
        "value": "{OtherTag} = 10"
      }
    }
  ],
}]
folderPath = '[default]System'
system.tag.configure(basePath=folderPath,
	tags=cfg,
	collisionPolicy='m'
)

Notes:

  • the tag defs must contain at a minimum the name key
  • all included property values must be complete, not partials. I.e. structures like alarms, writePermissions, etc. values cannot be provided as partials and merged, they must contain the entire structural definitions
3

Thank you very much, exporting to JSON first to get the formatting worked a treat!

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