Omron C200H-ID215

A device connected to the PC that sends a signal to the PC is called an input device; the signal it sends is called an input signal. A signal enters the PC through terminals or through pins on a connector on a Unit. The place where a signal enters the PC is called an input point. This input point is allocated a location in memory that reflects its status, i.e., either ON or OFF. This memory location is called an input bit. The CPU Unit, in its normal processing cycle, monitors the status of all input points and turns ON or OFF corresponding input bits accordingly.