Application Functions; Direct Access To The Link Devices - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

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APPLICATION FUNCTIONS

7.1 Direct Access to the Link Devices

Designate the link device to be directly accessed with "J \ ."
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The link devices (LB, LW, LX, LY, SB, SW) of the network module can be directly read
or written by sequence programs regardless of the link refresh of the CPU module.
With direct access, link devices that are not set within the range of the link refresh with
the refresh parameters can also be read or written.
CPU
J1\B10
J1\B100
MOV K20 J1\W100
= J1\W200 K300
J1\Y1000
J1\X1000
POINT
(1) The direct access of the link devices LX/LY is limited to the communication
with the block I/O master station set with the communication parameters. By
limiting the communication, data cannot be shared among multiple stations,
such as LB/LW, but 1:1 communication between predefined stations is
allowed.
(2) 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.
(3) Since the link direct device reads or writes data directly to the link devices of
the network module at the time of the instruction execution, the transmission
delay time can be reduced.
Network module
To other station
LB
From other station
To other station
LW
From other station
1:1 communication
with other station
LY LX
LX LY
MELSEC-Q
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