Mitsubishi MELSEC-Q Series User Manual page 147

3
CONCEPT FOR MULTIPLE CPU SYSTEM
POINT
When a stop error occurs, a "MULTI CPU DOWN (error code : 7000)" stop error
will occur at the CPU on which the error was detected.
Depending on the timing of error detection, a "MULTI CPU DOWN" error may be
detected in a CPU of "MULTI CPU DOWN" status, not the first CPU on which a
stop error occurs.
For example, if a stop error occurs in CPU No.2 and CPU No.3 is halted as a
direct consequence of this, CPU No.1 may be halted because of the stop error on
CPU No.3 depending on the timing of error detection.
CPU
0
1 2
3) Stop may occur with stop error detection of CPU No. 3
depending on the error detection timing.
("MULTI CPU DOWN" occurs.)
Diagram 3.36 Detection of stop error
Because of this, CPU No. different from the one of initial error CPU may be stored
in the error data's common information category.
To restore the system, remove the error cause on the CPU that is stopped by an
error other than "MULTI CPU DOWN".
In Diagram 3.37, the cause of the CPU No.2 error that did not cause the "MULTI
CPU DOWN" error is to be removed.
Diagram 3.37 Error display by PLC diagnosis
1) Stop with "OPERATION ERROR".
Slot number
1 2 3 4
Control CPU setting
3 1 2 3
2) Stop occurs with stop error detection of CPU No. 2.
("MULTI CPU DOWN" occurs.)
3.10 Operation for CPU module stop error
1
2
3
4
5
6
7
8
3
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