It’s hard to work almost anywhere in the automation industry without knowing something about OPC. It’s 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 PLC 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.
DCOM (Distributed COM) is the basic Microsoft transport technology that provides the standard communications architecture between the Clients and Servers. DCOM allows Clients on one Windows platform to read and write in 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 in 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, which is now being called OPC Classic, is now being displaced by OPC UA and OPC .Net (I’ll refer to both as OPC UA). Here’s ten things that you should know about OPC Classic and the transition to OPC UA:
1. OPC Classic has one major deficiency – DCOM. Even though that deficiency is mostly mythical. It’s really a lack of training and the lack of well-defined processes that frustrates users implementing OPC Servers.
2. DCOM does have some serious security flaws. Over the 10+ years since its inception, Ethernet security has advanced way beyond what was put into the original DCOM.
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 robust Security layer than is found in DCOM.
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 UNIX and other non-Microsoft platforms. This is very important as more and more business systems require communications with factory floor devices and many of those business systems are some flavor of UNIX.
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 systems.
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 PLC worms and Trojan horses, security is of paramount importance on the factory floor. If UA security is demonstrably better than 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 is something that we are all going to need to watch closely over the remainder of this year and next. I’ll be having a webinar in November to go into this in much more detail. Click here to sign up for the webinar or call 262-439-4999.