APPENDICES
Appendix 5 Method for Starting up the Previous Control System
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Appendix 5 Method for Starting up the Previous Control System
When both systems are simultaneously powered on, or when the reset switches of both
system CPU modules are simultaneously set to neutral position in a redundant system, the
redundant system will start up with system A as the control system.
Even when the power supplies for both systems go off temporarily due to a power failure
while system B is operating as the control system, system A will start up as the control
system when the power supplies of both systems are turned ON.
In order to start up with the previous control system, i.e., system B as the control system in
this condition, create the following program (Diagram App.14) that uses the special relay,
"Previous control system identification flag" (SM1519).
However, when mounting a network module on the main base unit or extension base unit,
create an interlock circuit as shown on the programs in Diagram App.20 and Diagram
App.22 before executing the SP.CONTSW instruction.
If battery error occurs in either system and device data cannot be held, the operation
cannot be guaranteed.
(1) When network module is not mounted
The following program shows an operation when the previous control system starts
with no network module mounted.
(a) Program Example
(b) Operation Image
1) System B is operating as the control system.
Diagram App.14 A program example
Diagram App.15 The system when System B is operating as the
control system
SP.CONTSW K1 M0
GOEND
SM1519
System A
Tracking cable
Standby system
System B
Control system
