Image Number 3 for United States Patent #6475036.
A signal input unit transmits detection signals derived from sensors such as switches, limit switches, or pressure switches to a programmable controller by means of serial transmission. A signal output unit transmits control signals from the programmable controller to control apparatuses such as solenoid-operated valve manifolds, indicator lamps, and buzzers by means of parallel transmission. The signal input units and the signal output units are integrated with each other into one unit and a number thereof is changeable. Further, an intermediate section and an end block are integrally assembled to the signal input units and the signal output units to construct a signal input/output apparatus.