Jeffersonian,
This NFPA stuff involves pretty complex issues, so I would recommend you consult someone for more detailed explanation.
Basically, for certain catagory safety stops, power cannot be reapplied automatically after pulling out an estop button in my knowledge. It depends on how much...
Check out Montalvo,
www.montalvo.com.
They have strain gauges (load cells) and amplifiers that you could feed right back to your electronic system without PLC conditioning.