1
9.
COMMUNICATIONS
IN
THE NO-PROTOCOL MODE
MELSEC-A
I
I
D8ta
Data
Data
Data
Data
Data
Data
(Received data)
1
2
3
n-1
n
(n+l)
-
(n+2)
-
(Completed code)
1
(b) By receiving the set data length (fixed length)
The AJ71C24 makes a request to read the received data to the
sequence program when
it
has received the set length of data from
an external device.
Using this method,
it
is possible to receive fixed length data.
Default setting is 127 words, but this value may be changed as
required. (For the procedure to change the data length setting, see
Section 7.4.2.)
OS
area
I
(Received data)
Data 1
7
Data (n+l)
-
Data (n+2)
-
(Completed data length)
(1):
Wing
received data
length
(2):
Received
data read request
T
II
'OINTS
1
(1) When both the receive completed code and the receive completed
data length are set to the special application area
in
buffer memory,
both
of
them are effective.
In
this case, the one which is met first triggers the read request signal
(Xnl) to the sequence program. See Section 7.4.1 and 7.4.2.
(2) The data received after the reception of the receive completed code
or the set length of data has been received is stored
in
the
OS
area
(279
bytes) of the AJ71C24. The data stored in the
OS
area is
transferred to the data receive area after the data previously stored
in this area has been read by the sequence program.
In
data communications through the RS-232C interface, the DTR
signal is turned
OFF
when DTR/DSR control is executed. DC3 code
is
sent when DCl/DC3 transmission control is executed to request
disconnection of data transmission from an external device because
the
OS
area where receive data is stored is smaller than 10 bytes.
See Sections 3.5.2 and 3.5.3.
U
3
Y
-.
1
U
Y
1
1
c
d
7
u
Ei
9-
10
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
