Mitsubishi Electric MELSEC-Q/L - Page 824

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8 INSTRUCTIONS FOR DATA LINK
8.1 Network Refresh Instructions
■CC-Link IE Controller Network and MELSECNET/H (PLC to PLC network)
When the scan time for the sequence program of host station is longer than the scan time for the other station, the ZCOM
instruction is used to ensure the data reception from the other station.
• Example of data communications when the ZCOM instruction is not used
• Example of data communications when the ZCOM instruction is used
For details on the transmission delay time on CC-Link IE Controller Network and MELSECNET/H (PLC to PLC network), refer
to the manuals below:
 MELSEC-Q CC-Link IE Controller Network Reference Manual
 Q Corresponding MELSECNET/H Network System Reference Manual (PLC to PLC network)
When the link scan time is longer than the sequence program scan time, data communications will not be faster even if the
ZCOM instruction is used.
Control station
program
Link scan
Normal station
program
0
END
END
0
0
0
END
0
END
0
END
Control station
program
0
END
0
END
0
ZCOM ZCOM
ZCOM
Link scan
Normal station
program
0 END 0 END 0 END
Sequence program
0
END
ZCOM
Link scan
0
ZCOM
END
0
ZCOM ZCOM 0
END
END