Multiplexing control system and multiplexing method therefor

A multiplexing control system, comprising:

• a sensor which detects a state variable in a process;
• a plurality of microcomputers wherein one of which is a master to which a process signal detected by the sensor is inputted and which outputs a control signal for the process and another of which is operated in asynchronously as a slave;
• and
• a process input/output unit which is provided in common for the plurality of microcomputers and distributes the process signal respectively to the plurality of microcomputers, the process input/output unit comprises a plurality of interface boards, each of which is provided with a memory corresponding to the respective plurality of microcomputers for storing the process signal, a single input processing unit which performs an input processing of the process signal detected by the sensor and a bus connecting the input processing unit and the respective memories for the plural interface boards,
• wherein, with respect to the input of the process signal from the input processing unit to the plural microcomputers, according to a master/slave relationship which is set in advance in the plural interface boards, to the master microcomputer the process signal is inputted from the input processing unit and to the slave microcomputer the process signal written in the memories provided in the respective interface boards is corresponding to the slave microcomputer is inputted.