| 摘要 |
PURPOSE:To improve reliability by incorporating a minor sequence controller (SQC) in the I/O module of an SQC, and by employing the doubled structure of the SQC and minor SQC to a part which requires safety specially. CONSTITUTION:The CPU25 of an SQC2, when a signal B which does not require double control is inputted to its input MD20, reads a control program, corresponding to the signal B, from a memory 26 and outputs a control signal C which does not require doubling, from its output MD21. When a signal A requiring the doubling is inputted, the CPU25 reads a corresponding program from the region 26a of the memory 26 and outputs a control signal D required for the doubling from the output MD21. On the other hand, the CPU32 of a minor SQC3 reads the same program as that in a memory area 26a corresponding to the signal A from a memory 33 and then outputs a signal E required for the doubling from an output circuit 31. Then, the signals D and E are ANDed at the outside of the SQC1 and only when the signals D and E coincide with each other, the output signal of the SQC1 is applied to a controlled system. |
