Mitsubishi MELSEC-A Series Reference Manual page 205

7. DATA LINK SETTINGS
(3) 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 link
parameters for the second tier is used for the M/L area.
2) The M/R area in the second tier and the empty area in the W0 to 3FF range is
used for the M/R area.
(b) The second half link parameters for the third tier can handle the empty area that
begins after the M/L area using the link parameters for the second tier.
However, exclude the range used as M/R area in the first half link parameters for
the third tier.
Fig 7.37 Assignment when the MELSECNET
POINT
When connecting a remote I/O station to the third tier, consider the range to be
assigned to the M/R area for the third tier with the link parameters for the second
tier and assign it.
Even when the MELSECNET composite mode is used for the third tier, the range
which can be used as M/R area is the W0 to 3FF range. Therefore, the similar
attention should be paid.
composite mode is used for the third tier
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