Swapped out part of a heat sealer. Relay on the old controller was periodically failing closed which is the wrong failure mode. Thinking I might pop a Pi or similar with a relay hat and wire the RS485 pins on the controller to act as an extra safety monitor/shut down power to the controller in the event of PV exceeds SV by too much. There's room in the sealer and it's a relatively cheap mod for some extra safety.
I've wanted to do something like that for a while anyway to set different PID tuning on startup to get up to temp faster then switch over to settings for stability and maybe do an auto-off timer. A lot of industrial stuff is simple enough and uses stuff that's sufficiently standardized that these sorts of things can be hacked together pretty easily.