Abstract: An input/output device monitors the transmission of information between a processor of a programmable controller and sensors and actuators of a process to be controlled. This device includes electronic circuits adapted for calculating the parities of the digital words which pass therethrough, these parities being compared with corresponding parities calculated by the processor which thereafter invalidates the words having two different parities.

Abstract: 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.

Abstract: An input card (7) is put in communication with apparatuses (16) the operation of which is to be monitored in order to initiate certain operations. A terminal-box (13) is interposed between the card (7), which possesses detector circuits (17), and the members (16).The two ends of each circuit (17) are associated with a respective inner terminal (12) of the terminal-box (13), and the two ends of each member (16) are associated with a respective outer terminal (14) of the terminal-box (13). Shunts (19,21) mounted in the terminal-box and connected to supply terminals (14a,14b) put one of the ends of each circuit (17) or member (16) at a common potential. The other terminal of each member (16) is connected to the other terminal of a circuit (17) by means of a connection (18).The invention is used to avoid the need for auxiliary terminal-boxes and cards with a common potential point.