Configure Trigger Input points

You can associate an Input point with a trigger point by defining the
Extended Description
 attribute of the Input point using the following expression:
<keyword>='<trigger_tag_name>';<condition>
Where:
This variable
Is
<keyword>
Either of the following:
  • TRIG
  • EVENT
Note:
The keywords must be written in uppercase.
<trigger_tag_name>
The name of the trigger point.
<condition>
Any of the following:
  • Any
  • Anychange
  • Nonzero
  • Decrement
  • Increment
Note:
The condition names are case-sensitive.
Any scan tag that is referenced in the
Extended Description
 or
Scan Tag
 point attributes must not be high-speed or have a scan rate higher than 1 second. Otherwise, the module will generate an error and you will not be able to save your point.
If you provide an expression in the
Extended Description
 point attribute, the point for which you have defined it is considered by the system to be trigger-based rather than scan-based. As a result, input is triggered when a new value is sent to the snapshot of the trigger point.
The TRIG keyword in the expression does not require any condition. Its default condition is
Any
 and you cannot change it.
The EVENT keyword requires a trigger condition to function properly. If you use multiple trigger definitions, you can separate them with a space, a comma, or a semicolon.
The following table lists the two keywords and their possible values.
Keyword
Trigger condition
This condition triggers an event on:
Example
TRIG
Any
-
-
EVENT
Any
-
-
Nonzero
Any non-zero value.
An event is triggered on a value change from "Pt Created" to 1 but it is not triggered on a value change from 1 to "bad Input".
Anychange
Any change as long as the value of the current event is different from the value of the previous event.
An event is triggered on a value change from 0 to "bad Input" or from "bad Input" to 0.
Increment
Any increase in the value.
An event is triggered on a value change from 0 to 1.
Decrement
Any decrease in the value.
An event is triggered on a value change from 1 to 0.
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