The invention relates to an input/output channel control block that comprises a number of successive input/output modules. The first is a control master module and the subsequent ones are expansion slave modules. Each expansion slave module comprises a processing logic unit as well as respective first signal port and a respective equal number of second signal ports and an equal number of third signal ports which are arranged at identical positions of each expansion slave module. The first signal port is connected to the processing logic unit, to which at least one fourth signal port for connecting an input/output bus terminal subscriber belongs, and a respective second signal port is connected to a third signal port. The control master module likewise possesses a number of third signal ports and a control logic unit for data exchange with a data bus and for targeted driving of the signal ports.