Mitsubishi Q12PRHCPU - 5.6 Online Program Change for Redundancy

5
REDUNDANT SYSTEM FUNCTIONS
5.6 Online Program Change for Redundancy
5.6.1 Writing to the CPU Module in STOP Status
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1
OVERVIEW
2
SYSTEM CONFIGURATION
3
TRACKING CABLE
4
PROCEDURE FOR STARTING UP A REDUNDANT SYSTEM
5
REDUNDANT SYSTEM FUNCTIONS
6
REDUNDANT SYSTEM NETWORKS
7
PROGRAMMING CAUTIONS
8
TROUBLESHOOTING
5.6 Online Program Change for Redundancy
In the backup mode, GX Developer writes the same program to the control system and
standby system CPU modules to keep them consistent.
Write to the control system and standby system is executed in the following conditions:
• Writing to the CPU module that is in STOP status ( Section 5.6.1)
• Writing to the CPU module that is running ( Section 5.6.2)
5.6.1 Writing to the CPU Module in STOP Status
(1) Operation When Writing to CPU Module in STOP status
When writing the parameters and programs either system CPU module, GX
Developer will write the same parameters and programs to the other system as well.
(2) Procedure for Writing to the Control System and Standby System
GX Developer writes to the control system first and then the standby system,
regardless of connection route, i.e., the system to which GX Developer is connected.
The following diagram shows the writing operation on the assumption that GX
Developer is connected to the standby system. (Write of program B to the control
system and standby system is executed in the order (1) and (2).)
Diagram 5.59 Procedure for Writing to the Control System and Standby System When CPU Module Writes
Program during STOP
Standby system
Control system
GX Developer
Tracking cable
1) Perform PLC write to control CPU module.
2) Perform PLC write to
standby CPU module.
Perform PLC write
for program B
Before writing After writing
Program A Program A
Program B
Program memory
Before writing After writing
Program A Program A
Program B
Program memory