R
This terminology has always baffled me as I couldn't comprehend what does it mean. Some say that in case of power failures a failsafe PLC would take process control values to pre-configured values which are safe positions as far as the operation is concerned... while others argue that since a process instrumentation is already configured to lock to failsafe position in case of failure, then what remains as the purpose of going for such an expensive option, i.e. 'failsafe PLC'?