486
28 FUNCTIONS
28.7 Redundant System Operation Setting
Standby system output setting
Output timing
When "Standby System Output Setting" has been set to "Enable", the output timing from the standby system in backup mode
is at the completion of the END processing or depends on the refresh group setting or refresh settings of each module. (
Page 65 Group setting for refresh)
Therefore, when a control system execution program is set in the refresh group setting, the I/O refresh is not performed while
the module is running because the program is not executed in the standby system. (When the CPU module is the STOP/
PAUSE state, the I/O refresh is performed at the timing of the END processing.)
To execute a program set in the refresh group setting in the standby system in backup mode, set "Both Systems Program
Executions Setting". ( Page 479 Program Execution in Both Systems)
Operation at system switching
The operation performed at standby system differs when "Standby System Output Setting" is set to "Enable". The following
table shows the operation performed when "Standby System Output Setting" has been set to "Enable".
For the program execution in both systems, refer to the following.
Page 479 Program Execution in Both Systems
Item New control system CPU module New standby system CPU module
Output (Y) The status of the old standby system is held and output
refresh is performed.
The status of the old control system is held and output refresh
is performed.
Direct access output (DY) In the program execution after system switching, data is
output when an instruction using the direct access output (DY)
is executed.
■For program executed in both systems
In the program execution after system switching, data is
output when an instruction using the direct access output (DY)
is executed.
■For program executed in the control system
No operation is performed because the program does not
operate.
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