PLC Glossary A - E

Address - (1) An alphanumeric value that uniquely identifies a specific input or output - the specific I/O rack, module, terminal, etc. (2) In PLC memory - an alphanumeric value the uniquely identifies where data is stored.

Analog Device - an apparatus the measure information that could be continuous (e.g. temperature gauge, pressure, etc.) as opposed to Discrete Device.

Encoder - a rotary device used to transmit position information.  The encoder generates electrical pulses as it moves - which are fed into a high speed counter.