Mitsubishi Electric MELSEC iQ-R-R00CPU - System; System Switching between the Control System and Standby System; System Consistency Check

35 BASIC CONCEPT
35.1 System
565
35
35.1 System
System A and system B
One system is specified as a system A and the other is specified as a system B to distinguish between two systems
connected with tracking cables. Set the system A or B with the engineering tool. ( Page 601 System A/B Settings)
When one system is set to system A, the other system is automatically set to system B, and vice versa.
Control system and standby system
The CPU module in one system executes programs to perform controls. The other system is in the standby state and does not
perform controls. The system that performs controls is called a control system and the system in the standby state is called a
standby system.
A control system or standby system is determined when both the systems are started and ready for tracking communications.
( Page 569 Determination of Control System/Standby System)
35.2 System Switching Between the Control System
and Standby 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.
For details on the system switching, refer to the following.
Page 609 System Switching
35.3 System Consistency Check
Whether both systems have the same configuration is checked to switch the system and continue the operation without
causing a system failure. ( Page 642 System Consistency Check)
(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.
(2)
(3)
(1)
System A
Control system
System B
Standby system
System A
Control system → Standby system
Stop error
System B
Standby system → Control system