Precautions For Using The Com Or Zcom Instruction; Precautions For Using The Adrset Instruction - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

Precautions for using the COM or ZCOM instruction

When the network module link refresh is performed by using the COM or ZCOM instruction, output from the remote I/O station
may change after system switching. To prevent this, do not perform the network module link refresh with the COM or ZCOM
instruction. For the COM instruction, whether or not to perform the network module link refresh can be set using SM775
(Selection of refresh processing during the COM instruction execution) and SD775 (Selection of refresh processing during the
COM instruction execution). Set SM775 and SD775 and perform only the I/O refresh and device/label access service
processing with the COM instruction.
: Selectable, : Not selectable
Instruction Refresh processing
COM instruction I/O refresh
Network module link refresh
Intelligent function module refresh
Refresh using the CPU buffer memory of the multiple CPU system (END)
Device/label access service processing (communications with the engineering tool, GOT,
or other external devices)
ZCOM instruction Network module link refresh
Intelligent function module refresh
*1 When the COM or ZCOM instruction is executed, tracking transfer is not performed. Thus, when the system switching is attempted after
execution of the instruction and before completion of tracking transfer, the system switching is performed without tracking transfer. Thus,
even though output to the network module is changed by the COM or ZCOM instruction with the CPU module in the control system, the
change will not be reflected to the CPU module in the standby system. After the system switching, the CPU module in the new control
system outputs old values to the network module, and output from the network module may vary.
*2 This processing is not selectable because no intelligent function modules can be mounted on main base units in a redundant system.
*3 This processing is not selectable because a multiple CPU system cannot be built in a redundant system.

Precautions for using the ADRSET instruction

Even though a file is written to both the control system and standby system, different addresses are assigned to the systems.
To continue the processing in the new control system, use the ADRSET instruction to obtain indirect addresses again.
In a redundant system

*1

*2

*3


*1

*2

29 PRECAUTIONS ON PROGRAMMING
29.1 Instructions Not Available in Redundant System
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