System Switching Between The Control System And Standby System; System Consistency Check; Operation Mode Of The Process Cpu - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

26.2
System Switching Between the Control System
and Standby System
In a redundant system, data link is performed between the redundant function modules connected with tracking cables and
data required for operation is transferred (tracking transfer) at every scan from the control system to the standby system. If an
error occurs in the control system, the standby system will function as the new control system and continue the control using
the data that the system has received.
System A
Control system
(1)
System A
Control system → Standby system
Stop error
For details on the system switching, refer to the following.
Page 441 System Switching
26.3

System Consistency Check

In a redundant system, whether both systems have the same configuration is checked to switch the system and continue the
operation without causing a system failure. ( Page 475 System Consistency Check)
26.4

Operation Mode of the Process CPU

A Process CPU operates in one of the following two modes.
Process mode
Use this mode when a redundant system is not built. When "Mode" has been set to "Process" at project creation with the
engineering tool, the Process CPU is started up in the process mode.
Redundant mode
Use this mode when a redundant system is built. When "Mode" has been set to "Redundant" at project creation with the
engineering tool, the Process CPU is started up in the redundant mode. ( Page 430 Creating a Project)
Set the redundant mode for both systems in a redundant system.
System B
Standby system
(2)
System B
Standby system → Control system
(3)

26.2 System Switching Between the Control System and Standby System

(1) The control system is operating without
errors. (Data is transferred to the standby
system from the control system at every
scan.)
(2) A stop error occurs on the control system.
(3) The standby system now functions as the
new control system and continues the
control using the data that the system has
received.
26 BASIC CONCEPT
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