OPC – Are its days numbered?

opc_classicIt’s hard to work almost anywhere in the automation industry without knowing something about OPC. It has been around forever and has been unarguably one of the most successful technologies to ever hit the factory floor.

OPC provides a standardized way to move data between two dissimilar systems as long as you are using Windows and Microsoft technology. OPC Servers embed the proprietary communications protocol of some automation device and make it available to one or more OPC Clients. So, a Siemens controller OPC server on Windows embeds the proprietary S7 protocol and provides the data to OPC Clients embedded in Historians, HMIs, Trend Analyzers and all sorts of other Windows devices.

COM (Component Object Model) and DCOM (Distributed COM) are the basic Microsoft transport technologies that provide the standard communications architecture between the Clients and Servers. DCOM allows Clients on one Windows platform to read from and write to Servers on the same machine or on machines distributed across a network.

Tens of thousands of these Clients and Servers have been deployed for thousands of devices over the years. OPC has found its way into most factory floor architectures. In fact, if you know of an automation environment that doesn’t use OPC in some way I’d like to hear about it.

Well, OPC, now often referred to as OPC Classic, is now being displaced by OPC UA. Here’s ten things that you should know about OPC Classic and the transition to OPC UA:


    • OPC Classic has one major deficiency – COM and DCOM. The COM technology is obsolete and unsupported by Microsoft.

2. COM does have some serious security flaws. Over the 20 or more years since its implementation, Ethernet security has advanced way beyond what was put into the original COM and DCOM. If you’re running an OPC application on an old Windows box you might as well put the sign “Hackers Welcome!” on your front lawn.

3. OPC UA is based on an SOA (Service Oriented Architecture) and the Web Services transport layer. The web services technology used in UA has a much more effective, robust, and up to date security layer than the one found in COM.

4. OPC UA combines the Data Access, Historian, Alarm and Events and all the rest of the OPC Classic specifications into a single entity with an Object-based model. This architecture is a huge step forward over Classic OPC.

5. The biggest advantage to having OPC UA in a device is the ability to provide seamless communication to systems based on Linux and other non-Microsoft platforms. This is very important as more and more enterprise applications require communications with factory floor devices and many of those are something other than Microsoft.

6. New OPC UA Client devices will probably include OPC Classic to ease the transition from Classic to UA.

7. OPC was not incompatibility-free. There were always incompatibilities between different specifications, different specification versions and more. And unfortunately, when you start introducing OPC UA you are going to find still more incompatibilities to deal with. One of the products that you’ll probably need is a UA to Classic translator.

8. Siemens is a big fan of UA. They strongly believe that OPC UA Servers in their PLCs will provide the network architecture of the future: a network architecture with seamless communication between those PLCs and Automation and Business application systems – local or cloud-based.

9. OPC UA is probably going to reduce your costs and hurt the business of OPC Classic Server providers like Matrikon, Kepware, and others. You can expect that PLCs and many other automation devices like drives, motion controllers, and other advanced devices will probably come with OPC connectivity as a standard option.

10. It is unclear how hard the IT folks will push for the adoption of UA. Since the high profile examples of PLC worms and Trojan horses, security has become of paramount importance on the factory floor. If UA security is demonstrably better the Classic we may see a strong push to UA from the IT departments. That could alter the deployment curve for this technology.

OPC UA deployment in the US is slow but growing in momentum. I expect the number of deployments and the companies requesting it to grow significantly in the coming year. For more information on connecting the factory floor with enterprise and cloud-based applications call 1-800-249-1612 or email me.