i agree with
@mburtis about PLC's, and all the other things he mentioned
because of your experience you are uniquely qualified to use a PLC
it takes machine knowledge of how they operate, move, and process material
it takes knowledge of the many varied sensors on the machines
i worked in a sawmill for 7 years. we went from a PLC controlled mill using a carriage and headrig,
to PLC controls and twin bandsaws, paired with slab grinders; each of which were controlled by a laser scanner on the infeed
they required a new position for every log going through them
many ppl dont realize it but a sawmill is not processing cookie cutter material, every tree trunk is unique and takes serious computing to get the max lumber from it. sawmills handle odd shaped pieces one at a time; not conveyors of dust or identical parts
i became rather familiar with our plc's i used them for trouble shooting the machines as well as creating a minor fix to limp through the rest of the shift, something like a sensor in a place that required LOTO and down time to replace them. i was not nearly the best one at it in the mill, but the best could do wonderful things to keep the machines running with out going in the field to fix it.
they were not programmers, but simply experienced electricians. they also had to troubleshoot and fine tune the plc programs when we got new machines and began the startup process
if you want to move on with plcs in a mill setting. work for a company that builds the kind of machines you would want to work around. get good enough to be on the team that installs them in a new mill. i watched those type guys during our rebuild and i could see enjoying that job a lot. it is the same old machine every time, but it is always a new mill with new challenges trying to integrate the machine into the existing process