Create Alarm For Memory String Tag

Ignition
1

Using Ignition v8.1.13

I have a child Memory String tag called devStatus within a UDT. The tag can have values that include Fault and Unknown. I want to create Equal Mode alarms for for when the value of devStatus equals Fault and Unknown. It doesn’t seem possible, the setpoint data type is Numeric.

Looking for a work around.

If there were System function to create an alarm I’d add a Value Changed script to devStatus but that function doesn’t seem to exist.

I suppose I can add a child Expression Integer tag (call it devStatusValue) and set its value so 1 and 2 for the String values and create alarms in this tag.

Any better ways to do this?

Thank you.

2

In the Alarm Mode Settings, you can change the Mode to “On Condition”. Then, for the “Is Active” field, hit the binding icon and select “Expression”. You can write your expression there and make it evaluate to 1 if the tag’s value is a certain string.

For example: {Value}="string"

Then you will not need to create an alarm on a separate expression tag.

6 Likes
3

Thank you, Eric!