Mitsubishi MELSEC-A Series Reference Manual page 153

7. DATA LINK SETTINGS
(2) Local station assignment
Assign the device range to be used by the local station for writing data to the link
relays (B) and link registers (W).
REMARK
The device range that can be assigned to the second half link parameters is
the range assigned to the first half link parameters: "(final device number) + 1".
(Example: If the range of B0 to FF is assigned to the first link parameters,
"B100" or later can be assigned to the second half parameters.)
If 0 point is assigned to the first half link parameters, assignment of the second
half link parameters can be started with B/W0.
7 - 15