Mitsubishi MELSEC Q Series Programming Manual page 871

(2) The ZCOM instruction does not perform the following processing.
(a) Communication processing between CPU module and programming tool
(b) Monitor processing of other station
(c) Read processing of buffer memory of other intelligent function module by serial
communication module.
(d) Low-speed cyclic data transmission of MELSECNET/H
*1
(3) PLC to PLC network
(a) 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.
(1) Example of data communications when the ZCOM instruction is not used
Control station
program
Normal station
program
(2) Example of data communications when the ZCOM instruction is used
For details of the transmission delay time on the PLC to PLC network
manual below:
• CC-Link IE Controller Network Reference Manual
• Q Corresponding MELSECNET/H Network System Reference Manual
(PLC to PLC network)
(b) 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.
Sequence program 0
Link scan
*1 : Controller network in CC-Link IE controller network.
(QCPU only)
0 END 0
Link scan
0 END
Control station
0 END 0
program
Link scan
Normal station
0 END 0
program
ZCOM
ZCOM END 0 ZCOM
END 0 END
0 END 0
END 0 END
END 0
ZCOM
ZCOM
END
END 0 ZCOM 0 ZCOM
ZCOM
1
2
3
4
6
6
7
8
*1
, refer to the
END
8-3