OPC UA PubSub SL Library Documentation¶

Description [1]¶

Function blocks for communication with the OPC-UA defined protocol for PubSub over UADP

The communication via the OPC UA Pub/Sub protocol provides, besides the Client/Server communication, another possibility to exchange data between network members, conforming to the rules of the OPC UA Foundation. The structure of the data can be freely defined (See: IEC_TYPES, DataSet) and is agreed in advance between the sender (Publisher) and receiver (Subscriber). This eliminates the need to transport additional (meta-) data. Data is transferred using the OPC UA PubSub SL library via UDP/IP according to the rules defined for UADP. A certain Publisher publishes his data to an unknown number of Subscriber. So sender and receiver do not know each other. Therefore the number of receivers has no effect on the sender. A feedback to the sender if his messages have reached the receivers cannot be done via the protocol. If required, such a feedback must be managed in an application-specific way. The data is transferred in a binary format according to the rules of the OPC UA Foundation. The conversion of the IEC data types into the corresponding OPC UA data types and vice versa is done by the OPC UA PubSub SL library.

The implementation follows the following profiles:

• Publisher: PubSub Publisher UADP Periodic Fixed Settings

• Subscriber: PubSub Subscriber UADP Periodic Fixed Settings

Please take a look to the overview of aviable set of function blocks:

Contents:¶

Indices and tables¶