Computer peripheral unit for controlling electric circuits - uses electromagnetic or electronic relays having operating and test contacts and controlled by computer programme outputs

摘要

The peripheral unit supplies a weak current whose return or not signifies whether the contacts are open or closed. Each of the input circuits is an 'exclusive or' logic circuit which indicates a change of contact state and a particular contact is identified by the value of an array of resistors activated by operation of the logic circuits. The coil of the relay selected for change is energised via a bistable circuit. ADVANTAGE - Peripheral unit provides simple contact control at low cost.