3.3 Multi-CPU Functions
Sub CPU Synchronization
3-99
Behavior when CPU Units Stop
*1. The Sub CPU Units will stop when the Main CPU Unit stops.
*2. The Main CPU Unit will not stop just because a Sub CPU Unit stops.
Behavior for Watchdog Timer Timeouts
If a watchdog timer timeout (WDT) error occurs for the Main CPU Unit or any Sub CPU Unit and the
CPU Unit goes down, the other CPU Units will have WDT errors and will go down.
Behavior When Turning Power ON/OFF
In a system that uses an Expansion Rack, if the power supply to the Rack for either the Main CPU Unit or
a Sub CPU Unit is turned ON or OFF, a hardware reset is performed for the other CPU Units and the
power supply turns OFF and ON again.
Behavior When Actual Hardware Does Not Agree with Module Configura-
tion Definitions in MPE720
The locations of the CPU Units are used by the MPE720 to automatically determine which CPU Unit is
the Main CPU Unit and which CPU Units are the Sub CPU Units. However, it will not be possible for the
MPE720 to correctly recognize the CPU Units for the following conditions in the Module configuration.
*1. You can check the Module configuration definitions in the Module Configuration Definition Tab Page on the
MPE720.
*2. The Sub CPU Unit will stop, but you will be able to batch-save data to the USB memory and will be able to use the
MPE720 to batch-read data.
CPU Run/CPU Stop Setting CPU Run/CPU Stop Status
Main CPU Unit Setting Sub CPU Unit Setting Main CPU Unit Status Sub CPU Unit Status
Run Run Run Run
Stop Run Stop
Stop
*1
Run Stop
Run
*2
Stop
Stop Stop Stop Stop
Module Configuration Defini-
tions
*1
Main CPU Unit Behavior Sub CPU Unit Behavior
When the Module configuration
definitions of the Main CPU Unit
are saved
The Main CPU Unit will operate cor-
rectly.
The scan service will stop.
*2
E.080 will be displayed on the CPU
Unit’s display.
When the Module configuration
definitions of a Sub CPU Unit are
saved
The scan service will stop.
*2
E.080 will be displayed on the CPU
Unit’s display.
The Sub CPU Unit will operate cor-
rectly.
When the Module configuration
definitions are not saved (e.g., for
INIT startup)
The Main CPU Unit will operate cor-
rectly.
The Sub CPU Unit will operate cor-
rectly.
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