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3. SPECIFICATIONS
MELSEC-A
(1) The functions available with the no-protocol mode cannot be used
together with the functions available with the bidirectional mode men-
tioned in Section 3.3.3. Select either mode using the mode setting
switch (see Section 4.3.1) and by settingthe bidirectional mode setting
area in the special applications buffer memory area (see Sections 3.5
and 10.2).
(2) The receive-completed code and the receive-completion data length
can be set and enabled at the same time. When both of them are
enabled, the received data read request to the sequence program is
made in response to whichever is received first by the AJ71 C24.
3 . 3 . 3
Functions available in
the
bidirectional mode
(1)
Functions in the bidirectional mode
Send (PC
CPU
-
computer)
Receive
(Computer
-
PC CPUl
Description
A PC CPU uses the TO instruction to
output data written to the AJ71C24
buffer memory area in unchanged
code to a computer.
When the AJ71C24 receives the
response message from
a
computer
after data send the AJ71C24 trans-
mits
a
send completed signal
to
the
sequence program.
A PC CPU uses the FROM instruction
to read data from the AJ71C24 buffer
memory which was transmitted b y a
compuier.
When the AJ71C24 receives the data
read completed signal from the se-
quence program, the AJ71C24 trans-
mits
a
response message for the data
receive to
a
computer.
Number of Point
Processed per
Communications
127 words
(default value).
Can be
changed with
the buffer size
0
setting (see Sec-
tions 6.4.4 and
6.4.5.)
l u r i n g RUN
Reference
Section
Section 10
(2) Setting data length setting for data send
The length of the data to be transmitted between an AJ71C24 and a
computer is set within the send message. (see Section 1.1.1 (2) (b)).
(a) When data is transmitted to a computer:
When the data to be transmitted to a computer is output from the
sequence program to an AJ71C24, the data length is written to
tee
buffer memory of the AJ71C24.
The AJ71 C24 sets the data length to a send message and transmits
it along with the data to a computer.
This allows the length of a send message to vary according to the
content and kind of data to be transmitted.
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