Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 205

6 PROGRAMMING
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POINT
(1) Link dedicated instructions must be executed in online mode.
Execution of the link dedicated instructions is not allowed in offline mode.
(2) Turn off the executing link instruction after the completion device turns on.
(3) When the link dedicated instruction is used to access the other station
programmable controller during network diagnosis, the execution of the link
dedicated instruction may be delayed.
After taking the following measures, perform network diagnosis processing and
execute the link dedicated instruction.
• Execute the COM instruction.
• Secure the communication processing security time for 2 to 3ms.
For the Basic model QCPU, High Performance model QCPU, Process CPU,
and Redundant CPU, set it by the special register SD315.
For the Universal model QCPU, set it by the service processing setting of
the PLC parameter (PLC system) of GX Developer.
(4) Do not execute any instruction that cannot be executed to AnUCPU stations.
If executed, the AnUCPU may detect "MAIN CPU DOWN" or "WDT ERROR"
and stop its operation.
(5) To execute such an instruction to all of the network which contains an
AnUCPU station, use group specification to exclude the AnUCPU station.
MELSEC-Q
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