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MELSEC-Q
3 SPECIFICATIONS
3.2.3 Number of connectable slaves
Please calculate the number of the slave which can be connected under the following
(1) and (2) conditions.
(1) The maximum data length of the slave station error information that
the QJ71PB92D can receive varies with the minimum station
number and maximum station number of the slave stations set in
the parameters, and can be calculated using the following
expression.
Maximum data length of receivable error information (bytes) =
MIN(12600/N - 10, 244)
a b
Provided that:
N = MIN((slave station's maximum station number -
slave station's minimum station 1) × 5, 300)
a b
MIN(a, b) = smaller of a and b
If the maximum data length (Max_Diag_Data_Len) of the error information
described in the GSD file of a slave station is greater than the value calculated by
the above expression, normal communication may not be made with that slave
station.
If normal communication cannot be made, try the following methods:
(a) Set the station numbers of the slave stations with no unused numbers in
between.
(b) Make setting on the slave station side to shorten the maximum data length of
the error information. (If possible)
(c) Using two or more QJ71PB92D's, reduce the number of slave stations per
module.
(2) Relation between parameter size and the number of system
construction
The parameter size which can be set in QJ71PB92D should meet the following
formula.
Note that the system construction which does not meet the following formula
causes the error of 1302H.
[5+ (number of parameter blocks for each station)] 128
(Number of parameter blocks for each station) is the sum total of the numbers
of parameter blocks calculated by the station.
