Mitsubishi Electric MELSEC-Q Series - Direct Access to Link Devices

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4.1.4 Direct access to link devices
Data can be directly read from or written to link devices (LB/LW/LX/LY/SB/SW) of the CC-Link IE Controller Network
module using the sequence program.
Specify a link device in the link direct device (J\) for direct access.
● To assure cyclic data integrity of data exceeding 32 bits, configure an interlock program. ( Page 76, Section 4.1.5)
● When a shorter link refresh time is desired
Remove any infrequently used link devices from the link refresh range, and directly read or write them using link direct
devices.
This reduces the points of the link refresh to the CPU module, resulting in a shorter link refresh time. ( Page 204,
Section 6.5)
● When a shorter transmission delay time is desired
Since the link direct device reads or writes data directly to the link devices of the CC-Link IE Controller Network module at
the time of the instruction execution, the transmission delay time can be reduced. ( Page 74, Section 4.1.4 (4))
Link refresh is performed in "END processing" of the sequence scan of the CPU module.
Control station
No.1
Network No.1
Normal station
No.2
Actual I/OActual I/O
CC-Link IE Controller
Network module
CC-Link IE Controller
Network module
Send
request
J1\B100
J1\B0
Send
request
MOV K20 J1\W100
= J1\W200 K300
Output
instruction
J1\X1100
J1\Y1000
CPU module
LB0
Station
No.1
Station
No.2
Station
No.1
Station
No.2
LB0
LB100
LB100
LW100
Station
No.1
Station
No.2
Station
No.1
Station
No.2
LW100
LW200 LW200
1000
1000
11FF
11FF
X Y LX LY LX LY
Cyclic transmission
Link refresh