Mitsubishi MELSEC-A Series Reference Manual page 209

7. DATA LINK SETTINGS
(3)
Fig 7.43 Assignment when the MELSECNET composite mode is used for the third tier
MELSECNET composite mode used in the third tier
(a) First half link parameters for the third tier
1) The range assigned to the master station for the third tier with the first half link
parameters for the second tier is used for the M/L area.
2) The M/R area for the second tier and an empty area in the W0 to 3FF range
is used for the M/R area.
(b) The range assigned to the master station for the third tier with the second half
link parameters for the second tier is used for the second half link parameters for
the third tier.
POINT
When the MELSECNET mode or the MELSECNET
selected as the operation mode for the third tier, consider the following points
when assigning device ranges.
(1) The device range assigned to the master station for the third tier is within the
B0 to 3FF range and the W0 to 3FF range. If the B400 to FFF range or W400
to FFF range is assigned to the master station for the third tier, the area
cannot be used for the first half link parameters (including the MELSECNET
mode link parameter) for the third tier.
(2) When the M/R area is required for the third tier, either provide an empty area
in the W0 to 3FF range with the link parameter for the second tier or use the
M/R area for the second tier.
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composite mode is