Mitsubishi MELSEC-A Series Reference Manual page 183

7. DATA LINK SETTINGS
(4) Assignment of link registers (W)
Fig 7.22 Link register (W) assignment example
(a) The empty area marked with *1 in the M/L area for the first half link parameters in
Fig 7.22 cannot be used as a substitute for data registers (D) in the master
station and all local stations.
This is also true for any empty area in the M/L area assigned with the second
half link parameters.
(b) The range that can be assigned with the second half link parameters is the range
assigned with the first half link parameters: (final device number) + 1 or later.
In Fig 7.22, since the range of W000 to 4FF is assigned to the first half link
parameters, W500 or later can be assigned to the second half link parameters.
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