Mitsubishi Electric MELSEC-Q/L - Page 825

8 INSTRUCTIONS FOR DATA LINK
8.1 Network Refresh Instructions
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■MELSECNET/H (remote I/O network)
The link refresh of the remote master station is performed by the "END processing" of the CPU module.
Since link scan is performed at completion of link refresh, link scan 'synchronizes' with the program of the CPU module.
When the ZCOM instruction is used at the remote master station, link refresh is performed at the point of ZCOM instruction
execution, and link scan is performed at completion of link refresh.
Hence, use of the ZCOM instruction at the remote master station speeds up send/receive processing to/from the remote I/O
station.
• When the ZCOM instruction is not used
• When the ZCOM instruction is used
For details on the transmission delay time on MELSECNET/H (remote I/O network), refer to the manual below:
 Q Corresponding MELSECNET/H Network System Reference Manual (Remote I/O network)
• The ZCOM instruction cannot be used in a fixed cycle execution type program or interrupt program.
• The Redundant CPU has restrictions on use of the ZCOM instruction.
Refer to the manual below for details.
 QnPRHCPU User's Manual (Redundant System)
Remote master
station program
Link scan
Remote I/O station
network refresh
I/O module
Intelligent
function module
0
END
Link refresh
I/O refresh
Auto refresh
0
END
0
END
0
Link refresh
Remote master
station program
Link scan
Remote I/O station
network refresh
I/O module
Intelligent
function module
0
Link refresh
I/O refresh
Auto refresh
Link refresh
END0 END
0
END 0
ZCOM
ZCOM
ZCOM