I have programmed PLCs with ladder logic before specifically allan-bradley SLC 500 and still have my certs for it. In industrial work we would keep a cleanly programmed plc on hand and reflash the program onto a malfunctioning PLC as needed. Sometimes I would pay attention to the input-output lights and look at the ladder logic schematics to troubleshoot a faulty sensor. Is it a big deal to know how to work with PLCs? Should I market that skill a little more in my resume?