PURPOSE:To enable the types of mode every time access instruction is producaed, by managing the instruction group of process input and output access unifiedly in program and storing whether each process input and output is in virtual or real access mode. CONSTITUTION:The process input and output is unifiedly managed so that the process input and output instruction of the execution progran 1 can be converted to the instruction to the hardware with the process input and output constitution defining table 28 of the process input and output managing unit 2. Further, the selection between the execution or test or program executed with the process input and output of the real plant and the simulation test performed with the giving and receiving of data and signals with the simulation model, is made with the simulation/real mode identification memory register, discrimination unit 21 and access mode switch 23 in the process input and output managing unit 2.
