OPC UA Book

The first OPC Unified Architecture Book, written by Wolfgang Mahnke, Stefan-Helmut Leitner and Matthias Damm one of the co-founders of ascolab.

OPC UA Protocols

Within OPC UA there are two protocols. An application programmer will recognize this only via the different URL he has to pass for binary protocol opc.tcp://Server and http://Server for WebService. Apart from that OPC UA works completely transparent with respect to the API.
uaprotocols
1. Binary protocol

  • best performance, smallest overhead
  • takes minimum resources (no XML Parser, SOAP and HTTP required -> important for embedded devices)
  • best possible interoperability (binary is explicitly specified and allows less choices during implementation than XML does)
  • only one single TCP port (4840) gets used for communication and can get tunneled or enabled through a Firewall easily
2. Webservice (SOAP)
  • best support from available tools. It can be easily used i.e. from JAVA or .Net environments
  • Firewall-friendly. Port 80 (http) und 443 (https) will usually work without additional configuration.

Since the available ANSI C stack supports both protocols, the expectation is that most of the final products may communicate via the more effective binary protocol.