In hydro you work your way up from helper to “A” mechanic up through to a “C” then at some point you might get a foreman’s position. My old foreman told me on many occasions that a good “C” mechanic always carried a good knife and a roll of black tape. Words of wisdom, there’s a lot of those you hear coming up through the ranks. It was pretty good advice. Even now as a communications tester I still use a lot of what I learned as a maintenance mechanic. Although now I’ve learned that a good “C” Tester always carries a small screwdriver and a reliable Digital Multi-meter –and knows how to get the most out of it. Maintenance mechanics use a lot of different tools and a lot of big equipment. The amount of knowledge and skill required to perform the job is quite impressive. You definitely have to know how to get the most out of your equipment.
The same holds true for SCADA. Although you may have software and specialized testing hardware available, much of what you are trying to troubleshoot can be done using good old fashion testing with a meter. You may have a lot of different technologies working together to act as your complete end-to-end communication loop. You could poll hubs using one type of communication media, and the last mile could use a different means altogether. The problem could be in between the hops, or it could be some type of equipment failure unassociated with switching and/or cable errors. Maybe you have a power source failure or a bad configuration that isn’t allowing any or partial data transfer. A lot of modern firmware based equipment has built in means for displaying or logging errors. Most modern communication equipment does, but sometimes you’ll come across old legacy gear that doesn’t. Even simple problems such as cable failures or improper wiring configurations can shut data transfer down. Some of the most annoying problems can boil down to very simple pitfalls. Power and cabling are high on that list along with bad configurations, noise, and component failure. Here is where your meter can come in very handy. Got a power source problem? It’s no problem for a DMM to measure voltage, amps, DC and/or AC. For cable problems look for continuity, resistance, and even capacitance. Errors in your signal, or no signal – check the frequency (provided you meter can cover the range you’re working in). Do you need to check the 4-20mA loops? Use your DMM for milliamps. Equipment running a little hot, maybe you have a meter that can sense temperature? Need to send a tone to chase down a twisted pair? No problem if you have the right meter. Having two meters with you comes in handy. Now about that screwdriver, what does that do? It does just what it’s supposed to do, tighten and loosen screws. It’s pretty handy when you think about it. One of my meters has a built in scope. I use it a lot, but most of the time I stick with the regular DMM. Make sure it’s cat III and true RMS. Most important; learn how to use it. If your looking for a tool that you just press a button and it spits out an answer you might find them, but you need to know how it’s getting that answer and what it means. You need to understand the problem and how to resolve it. Take the time to work with your meter on known working equipment. Take notes on what your getting for readings while the equipment is working. You should be able to find this information in the equipment specs, but you still need to check it yourself. See if your getting the values expected. Look at the signal going out during a poll or a command. Inject errors or faults (offline) and see if you can spot them with your meter. Everyday you should try to learn something new about your system and the equipment it takes to run it. Your meter isn’t the end all, but it is a good base to build upon. Practical knowledge and experience are sometimes worth their weight in gold. If you haven’t used your meter in a while, then go back to it. If you’re just starting out, make a point of learning how to use this incredibly valuable tool.

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