Efficient OPC UA binary encoding considerations for embedded devices

The implementation of software based OPCUA servers on computing platforms in actuators and sensors of the field layer remains a challenge due to the protocols high memory and bandwidth prerequisites. This paper discusses encoding aspects of OPC UA binary data representations for devices with limited random access memory and low fieldbus throughput, especially focusing on single-chip microcomputing platforms. Efficient and machine-friendly binary representations of OPC UA data models are derived by examining the structure of OPC UA data and optimizing their representation in regard to 8 bit serial, non-volatile memory components. Transport compression mechanisms, aiming to reduce bandwidth requirements in crowded or low bandwidth networks, are also introduced. While the memory usage of information models could be significantly reduced to (116 kB for Namespace 0), it was shown transport compression cannot yield bandwidth improvements unless data is compressed as a service.