g1956j,
you ask a question that's hard to answer and here's why.
our plant has the following plc's:
GE,Omron, Automation Direct, AB Slc 100/150, Micrologix family (1000, 1100, 1200, 1400), Slc 500's, PLC 2's, Plc 5's
i have to know hot to program all of them and modify the programs. each plant will be different and each part of the country will be different. in west Tennessee, AB is well supported, but in another part of the country, it's seimens.
PLC5 software is still current.
hope this helps,
james