APPENDICES
App
- 3
Appendix 1 Precautions for Accessing Redundant CPU System
POINT
To check which system in the Redundant CPU system is being accessed by the
CC-Link IE Controller Network board, create a program to monitor the following
special relays.
(1) When checking which system is being accessed, System A or System B
(2) When checking the operation system status
(3) Retry processing for error that occurs during system switching
processing
When the MELSEC data link library is used to access the Redundant CPU during
system switching being processed by the Redundant CPU, a system switching error
(error code: 4248
H
), CPU starting error (error code: 4004
H
), other system CPU module
error (error code: 4245
H
), access destination illegal error (error code: FFDF
H
) or
similar error occurs.
In this case, create a user program that checks the error code and performs retry
processing as necessary.
(a) The following indicates the functions that result in error if executed during system
switching.
SM1511
System A
identification
flag
• Identifies System A/System B of a redundant system.
• Remains ON/OFF even if the tracking cable is disconnected while the
redundant system is running.
System A System B
At the time of TRK.CABLE
ERR.(Error code: 6120) occurrence
(System not determined.)
SM1512
System B
identification
flag
SM1511
ON
OFF
OFF
SM1512
OFF
ON
OFF
SM1515
Control/
Standby
system
status
• Indicates the CPU module operation status
• Remains ON/OFF even if the tracking cable is disconnected while the
redundant system is running.
Control
system
Standby
system
At the time of TRK.CABLE
ERR.(Error code: 6120) occurrence
(System not determined.)
SM1516
SM1515
ON
OFF
OFF
SM1516
OFF
ON
OFF
Functions that result in error by system switching
MELSEC data link library
mdDevSetEx, mdDevRstEx, mdRandREx, mdRandWEx,
mdReceiveEx, mdSendEx,mdControl, mdDevRst, mdDevSet,
mdRandR, mdRandW, mdReceive, mdSend, mdTypeRead
