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APPX
Appendix 1 Precautions for Accessing Redundant CPU System
Error occurrence
The following example gives a flowchart for error occurrence at batch write.
*1 For details and corrective action of the error code, refer to the following manual.
QCPU User's Manual (Hardware Design, Maintenance and Inspection)
*2 Execute retry processing as required depending on the system specifications.
Automatic switching of communication path
When a communication error occurs during access to the Redundant CPU connected via MELSECNET/H, the
communication path is automatically switched to continue access to the control system.
Hereinafter, this automatic switching of the communication path is referred to as path switching.
The following describes the path switching conditions, checking method of path switching occurrence, and access examples
of path switching.
Path switching conditions
When access is being processed under the following conditions, access to the Redundant CPU is continued by path switching
even though a communication error occurs.
Note, however, that if a tracking error
*1
has already occurred at the start of communication, access to the control system is not
continued by path switching even if tracking is recovered after that.
*1 Includes the status in which either Redundant CPU is powered OFF or reset.
Conditions for continued access
Operation mode
Backup mode, Separate mode
Redundant CPU specification
Control system, Standby system, System A, System B
YES
YES
NO
NO
*1
*2
Start
Write processing
(mdSend instruction), etc.
Did an error occur?
End
Execute normal processing.
Process the error.
Execute wait processing.
Retry processing
Check the error code.
Does the error require retry
processing?
Summary of Contents for MELSEC Q80BD-J71GF11-T2
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Page 6: ...4 Disposal Precautions CAUTION When disposing of this product treat it as industrial waste ...
Page 118: ...116 12 MONITORING MEMO ...
Page 140: ...138 14 MELSEC DATA LINK LIBRARY MEMO ...
Page 142: ...140 15 PROGRAMMING 15 1 Precautions on Programming MEMO ...
Page 243: ...241 I U Utility 83 ...
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