Abstract: In a control system for controlling a very large number of remotely located input and output devices there is provided a novel control system having a single CPU coupled through a host interface module to a data and control transmission line. The host interface module on the transmission line receives information from and transmits information to a plurality of secondary interface modules having node addresses. The information being transmitted on the control and data transmission line is formatted to comprise one or two data bytes, an address and command byte, and an error checking byte to permit operation in a noisy electrical environment. Each said interface modules is further provided with high speed logic and an address counter for identifying node addresses and carrying out the commands and transmission of data without the requirement for software or firmware.