39 PRECAUTIONS ON PROGRAMMING
39.1 Instructions Not Available in System Using SIL2 Process CPU
691
39
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
*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.
*3 This processing is not selectable because a multiple CPU system cannot be built.
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.
Instruction
Refresh processing
In a system using the SIL2
Process CPU
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
Summary of Contents for MELSEC iQ-R-R00CPU
Page 2: ......
Page 151: ...9 MONITOR FUNCTION 9 1 Real Time Monitor Function 149 9 MEMO ...
Page 323: ...18 SEQUENCE SCAN SYNCHRONIZATION SAMPLING FUNCTION 321 18 MEMO ...
Page 330: ...328 20 ROUTING SETTING 20 3 Precautions MEMO ...
Page 423: ...26 BASIC CONCEPT 26 8 State Transition of the Redundant System 421 26 MEMO ...
Page 1014: ...1012 APPX Appendix 15 Added and Enhanced Functions MEMO ...
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