Specifications

2 - 8

2 MULTIPLE CPU SYSTEM

2.1.7 Processing at a CPU DOWN error occurrence by a PLC CPU or Q173HCPU/

Q172HCPU

In the Multiple CPU system, the system operates differently when CPU No. 1

generated a CPU DOWN error as compared with when CPU No. 2, 3 or 4 did.

(1) When CPU No. 1 generated a CPU DOWN error

(a) When the PLC CPU of CPU No. 1 generated a CPU DOWN error, all

PLC CPU/Q173HCPU/Q172HCPU of CPU Nos. 2, 3 and 4 generate a

MULTI CPU DOWN error (error code: 7000) and the Multiple CPU system

stops.

(Note-1)

(b) Recover the system using the procedure below:

1) Check the cause of the error that occurred in CPU No. 1 using the PC

diagnostic function of GX Developer.

2) Remove the cause of the error.

3) Reset the PLC CPU of CPU No. 1 or restart the power.

Resetting the PLC CPU of CPU No. 1 or restarting the power resets all

CPUs in the Multiple CPU system and the system is recovered.

(2) When CPU No. 2, 3 or 4 generated a CPU DOWN error

If the PLC CPU, Q173HCPU or Q172HCPU of CPU No. 2, 3 or 4 generated a

CPU DOWN error, the entire system may or may not stop depending on the

setting of "Operation Mode" in the Multiple CPU Settings tab.

By default value, all CPUs will stop when any of the CPUs generates a CPU stop

error. If you do not wish to stop all CPUs following an error generated in the

PLC CPU, Q173HCPU or Q172HCPU of a specific CPU or CPUs, click and

uncheck the CPU or CPUs that will not stop all CPUs upon generating an error.

(See arrow A.)