If someone asked what’s the latest hot topic in industrial automation, I guess you have to say Wireless.   All the news releases, conference topics and vendor direction statements have something to say about wireless.  (in fact Gary’s latest post is about wireless).    Since everyone’s talking about wireless, how come you don’t hear a lot about wireless OPC?    Well since most wireless Ethernet systems today have good reliability and bandwidth, running OPC or any other DCOM based application is practically no different from a physical LAN based setting.  So to date it hasn’t been much of an issue.

However, if you are in a wireless environment that is prone to dropping the connection  (large distances, roaming equipment, lots of interference) than a DCOM based architecture like OPC would experience troubles.    (Just ask anyone who ever tired communicating OPC over a dial-up modem or sketchy satellite link).    Since telemetry based applications such as RTU’s, remote PLC’s, radio modems, alarm callout systems are very common in SCADA architectures, it didn’t take long for OPC solutions to evolve.

The most common solution is to use an OPC Server that was designed for typical telemetry protocols.   OPC Servers for Modbus, MOSCAD and DNP 3.0 are examples of protocols designed that handle the communication requirements of talking to remote field devices.   In cases where the protocol or architecture constraints require the OPC client and server to be separated by an unreliable network, then OPC Tunneling has become another popular solution.  This effectively removes DCOM from the equation, and often offers a more secure option as well.

OPC UA will create interesting new possibilities for OPC in wireless environments.   It’s service based architecture, cross-platform targeting and rich information model will open up a whole new field of OPC based wireless applications.   It will be very interesting to see what develops.