Mitsubishi Electric MELSEC Q Series Reference Manual page 273

7 APPLICATION FUNCTIONS
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POINT
The following must be performed before operating the system
• Powering ON/OFF of other stations (including those on the standby system)
If the above operation is performed during system operation, a MELSECNET/H
module on the control system may detect a communication error and a system-
switching request may be issued.
When the system-switching request is issued before startup of the standby system,
a continue error, "CAN'T SWITCH" may be detected in the control system CPU.
Generally, normal system control is continued even if "CAN'T SWITCH" is detected.
However, in the case of the system where error detection will stop the control,
program the system to prevent such a control stop.
For the method for automatically clearing the "CAN'T SWITCH" error, refer to the
QnPRHCPU User's Manual (Redundant System).
REMARKS
For the details of system switching, refer to QnPRHCPU User's Manual (Redundant
System).
MELSEC-Q
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