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CHAPTER 4 STARTING UP MULTIPLE CPU SYSTEM
4
4.6 System Operation When a Stop Error Occurs
If a stop error occurs, "MULTI CPU DOWN" (error code: 7000) will occur in the CPU module where the stop error has been
detected. Depending on the timing of error detection, "MULTI CPU DOWN" may be detected in another CPU module due to
secondary-occurred "MULTI CPU DOWN".
For example, if a stop error occurs in CPU No.2, the operation of CPU No.3 stops. Depending on the timing of error
detection, the operation of CPU No.1 may stop due to the stop error of CPU No.3, not the error of CPU No.2.
Because of this, CPU No. different from the one of the first error CPU module may be stored in the common error information
field. To restore the system, eliminate the error cause of the CPU module that has been stopped by an error other than
"MULTI CPU DOWN".
In the following example, the error cause (other than "MULTI CPU DOWN") of CPU No.2 shall be eliminated.
(3) System restoration procedure
The following is the procedure for restoring the system.
1. Check the error CPU No. and error cause in the "PLC diagnostics" window using the programming
tool.
2. Eliminate the error cause.
3. Reset CPU No.1 or power off and on the system.
All the CPU modules in the multiple CPU system are reset and the system is restored.
1 3
2
2) The CPU module stops due to a stop error in CPU
No.2. ("MULTI CPU DOWN" occurs.)
3) The CPU module may stop due to a stop error in CPU No.3
depending on the timing of error detection.
("MULTI CPU DOWN" occurs.)
1) The CPU module stops due to "OPERATION ERROR".
CPU 0 1 2 3 4
Slot number
Control CPU setting
1 3
2
Eliminate this error cause.