Several years ago, your facility completed a major project that converted plant data systems, such as statistical process control (SPC), from hard-wired Ethernet to wireless. Over the past few months, various department heads have lodged complaints about “missing data” and “problems with being able to read field data in real time.” Your boss suspects the problem is in the equipment. Where do you begin?
With wireless, you gain configuration flexibility. For example, you can move an operator panel to the other side of a line without needing to run a new Ethernet cable. But one of the amusing things about “wireless” systems is that they nearly always contain far more wire, wired components, and connectors than they would if hard-wired point to point.
The “wireless” aspect describes the “end points” in the system, not its backbone or trunks. Wireless is equipment-intensive — especially if you need to project it around various electromagnetic barriers, such as steel columns. Consequently, a “wireless” system has additional choke points and points of failure over a hard-wired version of the same thing.
Your first step is to isolate where these problems are occurring. You may find a single switch is handling too much bandwidth. Offloading some nodes onto a new switch may solve that problem.
- Review the PMs. Are the switches, connectors, and power supplies properly maintained per manufacturer's recommendations?
- Conduct a visual inspection. Look for damaged cables and interference sources.
- Inspect for compliance with NEC Art. 250, Part V.
- Conduct a security inspection. Hire an outside security expert to audit your system. A correctly designed system won't exhibit bandwidth problems unless loads have changed dramatically. If someone’s hacking your system, however, that could be the source of “bandwidth drain” and the problems you’re experiencing.