Understanding subscriber tools

The purpose of the MultiSubscriber and DALMultiSubscriber tools is to subscribe to topics and observe their published values. The tools look very similar and are functionally equivalent, with minor variations.

The DALMultiSubscriber uses the PubSub Data Access Layer (DAL) Application Programming Interface (API) to connect to the PubSub system, whereas the non-DAL version uses a lower-level PubSub API. The PubSub DAL API is built on top of the lower-level API and has additional support for automatically healing lost PubSub connections and restoring previously held subscriptions.

To subscribe to a topic, enter the topic string, and then select Add Subscription. Optionally, you can select Subscribe with integrity. For many of the reserved topics, or topics secured by Windows or SCADA groups that the user is not permitted to view, a subscription can be added successfully but no data should be expected.

The Save and Load commands are available from the File menu to enable the tools to export the currently subscribed topics to a file, as well as, to import a previously saved file. The subscriptions saved in this manner can be imported by either tool. The act of importing automatically adds subscriptions for the imported topics if the tool is currently connected to the PubSub system.