METHOD AND APPARATUS FOR PROTECTING AND MONITORING THE TRANSMISSION OF INFORMATION BETWEEN THE CENTRAL UNIT OF A PROGRAMMABLE CONTROLLER AND THE SENSORS AND/OR THE ACTUATORS OF THE CONTROLLED PROCESS

An input/output device is used for a programmable controller having on input/output cards a plurality of electronic channels forming the logic interfaces between the connection bus with the central unit and the sensors or the actuators connected to the controllers; this device further uses electronic circuits for monitoring the good transmission of input/output signals by the adaptation interfaces providing for the galvanic isolation of the bus with respect to the sensors and actuators of the controlled automatism.