Trigger Types

Set the trigger type in the Trigger screen area. You use the trigger type to define the trigger conditions that are checked when an event occurs.

Trigger Type	Description
Always	The event always triggers the defined follow-up action. Example In the notification process, a notification message is delivered whenever the value of a subscription item changes. Always is the default setting. Note For the setting Always you do not need to define a condition using the expression editor.
OnTrue	If you set OnTrue and PCo evaluates the trigger expression that you specified as `TRUE`, PCo triggers the follow-up action. The trigger expression must then be evaluated as `FALSE` before it can be evaluated again as `TRUE` for triggering a further follow-up action. You use the setting OnTrue if you want to receive a notification message if a rare event occurs. Example You are monitoring a boiler with PCo. You specify that the `boiler temperature tag` is to be sent to PCo if the measured value falls short of or exceeds the permissible temperature bandwidth. For this you select the trigger type `OnTrue`. You use the expression editor to enter the formula `TAG_TEMP<57 \|\| TAG_TEMP>63` as the trigger condition. If the measured value lies below 57°C (134.6°F) or above 63°C (145.4°F), PCo creates a notification message and sends it to the destination system.
OnFalse	With this setting PCo always triggers a follow-up action if the trigger expression that you defined is evaluated as `FALSE`. The trigger expression must then be evaluated as `TRUE` before it can be evaluated again as `FALSE` for triggering a further follow-up action.
WhileTrue	If PCo evaluates your defined trigger expression as `TRUE`, PCo generates follow-up actions. This happens until PCo evaluates the expression as `FALSE`. You choose the setting WhileTrue only for events that occur frequently. For method notifications, WhileTrue has the same effect as OnTrue. Example You want to monitor a belt that has frequent interruptions. Therefore, you want to receive notification messages from PCo constantly while the belt is running.
WhileFalse	If your defined trigger expression is evaluated as `FALSE`, PCo generates follow-up actions. This happens until the expression is evaluated as `TRUE`. For method notifications, the trigger types WhileFalse and OnFalse have the same effect. Example You want to monitor a belt that has frequent interruptions. Therefore, you want to receive notification messages from PCo constantly while the belt is running.

If you select the trigger type OnTrue, OnFalse, WhileTrue, or WhileFalse, you need to use the expression editor to create a Boolean expression to define the trigger condition. The expression must be able to be evaluated as true or false.

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Trigger Types

Procedure

Example