28 FUNCTIONS
28.14 External Input/Output Forced On/Off Function
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Behavior of forced on/off
This section describes the behavior of forced on/off in the following cases.
■At operation mode change
Even if the operation mode has been changed (backup mode separate mode, or separate mode backup mode), the
forced on/off registration information before the change remains.
■At system switching
Even if a system switching is performed, the forced on/off registration information before the switching remains since forced
on/off registration information is transferred from the control system to the standby system.
■When the CPU module of only one system is powered off and on or is reset
■When tracking communications are disabled
When tracking communications with the standby system are disabled or the system is operating only with the control system,
forced on/off can be registered or registration of forced on/off can be canceled to the control system. Forced on/off registration
information of the control system is reflected to the standby system when tracking communications are enabled.
Reflection timing of forced on/off registration information to the standby system
This section describes the reflection timing of forced on/off registration information to the standby system.
■When the synchronous tracking mode is used as a tracking mode
The reflection of forced on/off registration information to the standby system delays for one scan (maximum).
■When the asynchronous tracking mode is used as a tracking mode
The reflection of forced on/off registration information to the standby system may delay for several scans.
Precautions
The following describes precautions on this function.
• When reflecting forced on/off registration information in the first scan is required, start the standby system in the STOP
state, and switch it to the RUN state after checking that the forced on/off registration information of the control system is
reflected to the standby system. When the standby system is powered on while the control system is operating, forced on/
off registration information may not be reflected in the first scan if the standby system is started with its RUN/STOP/RESET
switch set to the RUN state.
Condition Behavior
Backup mode Control
system
Although a system switching is performed, the forced on/off registration information of the new control system
remains while the CPU module of the old control system is off or in the reset state. After the CPU module of the old
control system is powered on or is reset, the forced on/off registration information of the new control system is
reflected to the new standby system.
Standby
system
The forced on/off registration information of the control system remains while the CPU module of the standby system
is off or in the reset state. After the CPU module of the standby system is powered on or is reset, the forced on/off
registration information of the control system is reflected to the standby system.
Separate mode Control
system
The forced on/off registration information of the standby system remains while the CPU module of the control system
is off or in the reset state. After the CPU module of the control system is powered on or is reset, the forced on/off
registration of the standby system is canceled in a batch and no forced on/off is registered in both systems.
Standby
system
The forced on/off registration information of the control system remains while the CPU module of the standby system
is off or in the reset state. After the CPU module of the standby system is powered on or is reset, the forced on/off
registration information of the control system is reflected to the standby system.
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