Input points

PI Interface for OPC DA uses the following three types of input points for collecting data from OPC DA data sources:

• Advise points

  Input is collected and stored in PI points when the OPC server updates item values in the server cache, based on the scan class configured for the PI point. The interface updates PI points when advised that a value changed.

• Event points

  Input is stored in PI points when the interface is notified of an updated trigger point. The interface reads the event points, which can be associated with an event group, from the OPC server.

• Polled points

  Input is collected and stored in PI points based on the scan class configured for the point and the update rate of the OPC server. The interface polls the OPC server at a regular rate.

All three types of points are received asynchronously by the interface.