6.
DATA COMMUNICATIONS
USING
AN
M
:
N
MULTIDROP
LINK
MELSEC-A
(5)
A
slave station that has finished data communications with PC CPUs
transmits the communications completed code to the master station.
An
example of the message format is shown in
(6)
below.
Slave stations which are not performing data communications with PC
CPUs check the transmission
of
the communications completed code.
During this checking, the slave stations must not perform data com-
munications with the master station.
(6)
The master station that received the communications completed code
transmits a response to the slave station that transmitted the com-
munications completed code.
(An example of data communications using dedicated protocol
1)
Wer
station
computer
(WH)
After the processing given
in
(6)
is completed
or
when the access right
.time of a slave station with the access right exceeds the maximum data
communications time:
(a) The master station waits for a communications request from a slave
station.
When the master station receives a communications request, the
processing mentioned
in
(2)
is executed.
(b)
Until data communications with PC CPUs is required, a slave station
does not perform data communications with the master station.
When data communications with PC CPUs is required, the process-
ings
in
and after
(1)
are executed.
6-
10
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