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

11.2
System Switching Between 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 from the control system to the standby system at every scan. If an error occurs in the
control system, the standby system will function as the new control system and continue operation using the data that has
been 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 374 System Switching
11.3

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 413 System Consistency Check)
11.4

Operation Modes of the Process CPU

The Process CPU operates in one of the following two modes.
Process mode
A mode to use the Process CPU in a system other than a redundant system. Select "Process" for "Mode" when creating a
project using the engineering tool. The Process CPU is started up in process mode.
Redundant mode
A mode to use the Process CPU in a redundant system. Select "Redundant" for "Mode" when creating a project using the
engineering tool. The Process CPU starts up in redundant mode. ( Page 64 Creating a Project)
In a redundant system, set the redundant mode for the Process CPU in both systems.
11 BASIC CONCEPT OF REDUNDANT SYSTEM
158

11.2 System Switching Between Control System and Standby System

System B
Standby system
(2)
System B
Standby system → Control system
(3)
(1) The control system is operating normally. (The control system
transfers data to the standby system at every scan.)
(2) A stop error has occurred in the control system.
(3) The standby system functions as the new control system and
continues operation using the data that has been received.