What defines a system as having absolute position control? Yes, I know the simple definition is: having closed loop position feedback and the ability to know the exact position after a power down/failure. What I want to know is what are the options for achieving this? I have been told the only true "absolute position control" is done using a absolute encoder/resolver. My arguement is that the same end result can be achieved using other means. An absolute encoder decodes sine/cosine waves (via onboard electronics) and can output this result as BCD and other formats. This result is remembered/stored by the encoder upon power down/failure. If I use an incremental encoder with a high speed counter PLC module (encoder mode) and store the counter value in non-volatile PLC memory doesn't this achieve the same result as an absolute encoder. The HSC module counts pulses up/down depending on direction given by encoder signals.