10.
COMMUNICATIONS
IN
THE BIDIRECTIONAL
MODE
MELSEC-A
10.7
Basic
Program
to
ReadWrtte
Buffer
Memory
The following describes a basic sequence program
to
bidirectional read and
write data to and from the
AJ71
C24
buffer memory.
L
(1)
Reading data from the receive area
(FROM,
FROMP, DFRO, DFROP)
\-I-
Xnl
(Received
dah read
request)
(1
)
(Received
data read completed)
c
t
-1
(1) Read reauert
,p-
‘V
1
c
StwesthereaddatalengthtoUmindexregfsierQ).
(3)
Received d8ta read
Read6~~eddatadthereadr.t.ivedddabngthfromthe
mivod
data
storage
area
of
buffer
memory.
(4)
Read completed
c
I
I
Turns
ON
th
red
completed
signal
(Y(n+l)l)
aftertho
rsciewd
Data read
by
program (3) is procewed as
the
recieved data.
Example:
To
read the data
of
(n+l)
words from the area, beginning with
buffer memory address
80H,
to the area beginning with
DO
when the
AJ71C24
I/O
numbers are allocated to
130
to 14F (unit: word).
~
+IIIIIII$
(areabeginningwith81H)
From buffer memory
I
I
I
L
10-
18
c
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