Notification

Definition

You use notifications to define under which circumstances, with which data, and to which destination you want PCo to send information when a specific event occurs. A distinction is made between two classes of notifications:

  • Tag-based notification

    The static and the versioned notifications form the basis for the notification messages that are to be generated and sent later. The notification messages are always generated when events occur that fulfill the defined conditions. A notification message informs the destination system about the event that has occurred. See also: Static Notification and Versioned Notification.

  • Method Notification

    You can use a method notification to activate a method of an OPC UA server or a Web server and define which action you want to be executed when the method is called up. Here you can also define a destination system call, if necessary, that is executed when the method is called.

You can add multiple notifications to an agent instance. This is important if, for example, you want to send a notification message to different destination systems.

Use

You can use notifications in the notification process to send messages to destination systems via PCo when specific events occur. A notification always contains the following information:

  • Conditions

    When the user-defined event occurs, PCo checks the conditions and decides whether a notification message needs to be created and sent to the destination system.

    These conditions are also evaluated for method notifications, however these conditions need to be formulated so that only exactly one method notification is executed when the method is called.

  • Output

    You define the output expressions and output values that you want to be output in the message. In the notification process, the output expressions are based on the subscription items of the agent instance.

    For method notifications for an implementation of enhanced method notification (EMP), the output expressions are determined from the input variables that are provided by the EMP implementation.

    In each case, the output expressions form the input parameters of the subsequent destination system call.

  • Message delivery

    In the notification process you define how the messages are to be delivered. For method notifications, the corresponding tab is hidden because the destination system call is made directly and not using the message queue.

  • Destinations

    You can specify one or more destination systems for a notification message.

    For method notifications you can only define one destination system.

When you add a notification, you can specify, by selecting the relevant option in the dialog box, which type of notification you want the system to create. See also: Functions for Notifications.