Mitsubishi Q12PRHCPU - 7.4 Precautions at System Switching Occurrence

7
PROGRAMMING CAUTIONS
7.4 Precautions at System Switching Occurrence
7 - 17
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
7.4 Precautions at System Switching Occurrence
(1) Precautions regarding access to intelligent function module and
external device
Depending on timing of system switching occurrence such as turning power supply
OFF, tracking transfer processing may be discontinued, and the device data may not
be reflected to the new control system CPU module after switching systems.
In this case, the data output and the device data of the new control system CPU
module may mismatch.
When the CPU module communicates with the intelligent function module or external
device using the output (Y) and the buffer memory, a program may not operate
properly due to device data mismatch after switching systems.
Diagram 7.17 shows operations when the system switching occurs before the tracking
transfer processing is completed after outputting the output (Y).