1444
14 REDUNDANT SYSTEM INSTRUCTIONS
14.2 Disabling/Enabling System Switching
14.2 Disabling/Enabling System Switching
DCONTSW, ECONTSW
• DCONTSW: This instruction disables manual system switching.
• ECONTSW: This instruction enables manual system switching.
■Execution condition
• When the DCONTSW instruction is executed in the standby system, the system switching operation in the control system is
disabled.
• When the ECONTSW instruction is executed in the standby system, the system switching operation in the control system is
enabled.
• The system switching operation in the control system is enabled by default.
• These instructions can only be executed in the standby system. Even if these instructions are executed in the control
system, no processing is performed.
To execute these instructions in the standby system in backup mode, write the instructions in a program
executed in both systems or in a POU called by a program executed in both systems. For details on executing
a program in both systems, refer to the following.
MELSEC iQ-R CPU Module User's Manual (Application)
Ladder ST
ENO:=DCONTSW(EN);
ENO:=ECONTSW(EN);
FBD/LD
Instruction Execution condition
DCONTSW
ECONTSW
RnCPU
RnENCPU
RnSFCPU RnSFCPURnPCPURnPCPU
(Standard) (Safety)
(Redundant)
(Process)