Mitsubishi MELSEC Q Series Programming Manual page 920

SP.CONTSW
(2) If system switching was unsuccessful, the error flag (SM0) is turned ON and an error code is
stored into SD0.
• The tracking cable is disconnected or faulty.
• Hardware fault, power-off, reset or watchdog timer error occurred in the standby system.
• Watchdog timer error occurred in the control system.
• Preparations are being made for tracking transfer.
• Communication time-out occurred.
• Stop error, excluding watchdog timer error, occurred in the standby system.
• The operating status differs between the control system and standby system.
• Memory copy is being executed from the control system to the standby system.
• Write during RUN is being executed.
• Network fault was detected by the standby system.
Program Example
(1) The following program executes system switching on the leading edge of the system
switching command (M100).
If the system switching command (M100) remains ON, the SP.CONTSW instruction is also
executed by the new control system CPU module after system switching. Therefore, M101 is
added to the execution conditions as a consecutive switching prevention flag.
[Ladder Mode]
11-4
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
(Error code: 6220)
[List Mode]
Step Instruction Device