… until the perception of OPC quality improves.   The ‘flogging’ bit comes from a recent ControlGlobal article with the teaser line “There are people who would rather take a flogging than maintain an OPC installation.”   The piece talks about OPC and Modbus, and their role in Process Control.  It’s basically a push for Foundation Fieldbus HSE (High-Speed Ethernet), and has ‘disparaging remarks’ on OPC (some might say FUD) as a competing standard.

I’ll not get into a spitting match over the OPC comments.  I know not every OPC installation is free of problems, and have been personally involved with more than a few that were quite painful.   There are those that see OPC in an unfavorable light since it is difficult to separate issues with OPC, DCOM problems, items beyond the scope of the OPC specifications and problems with server quality (see my last post).   I’ve posting on this in the past, and don’t want to ‘flog a dead horse’, but let me highlight a few points.

No one ever said OPC was intended to replace every protocol known to man and solve all the world’s connectivity problems.  Neither was Modbus, Profibus, FF HSE, or any other protocol someone might be selling you. Any standard or specification, including OPC UA, can only cover so much.   OPC is dedicated to open connectivity for industrial automation.  That means a product from vendor A will be interoperable with a product from vendor B.   OPC can be plug-and-play but if it is not treated with the importance that its place in the system warrants, or if it is not used as designed it will cause problems.  Users have to be conscious of system requirements and architecture.  They also have to look at the software quality, engineering services expertise and product support of the OPC vendor.   The specification and the Certification process ensures the OPC products will be interoperable.  However, like any technology, OPC requires expertise to architect, implement, and support.

Think of it in terms of hardwiring IO terminals.  Boiled down it’s simply tightening a screw on a wire.   Even my four year old son can do that, but surprisingly no one has hired him yet, even though Alberta is starving for workers.      Of course, we know there is more to it. You needs an engineer to design the electrical system for any industrial application and a certified technician to do the final wiring. Like any large scale industrial application of technology not only do you need the right people doing the work, the project must follow best practices before, during, and after the technology is deployed.   Implementing software, even OPC, is no different.