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9. COMMUNICATIONS
IN
THE NO-PROTOCOL MODE
MELSEC-A
9.4
Basic Program to ReadIWrite Buffer Memory
F
l
1 1 1 Read request
The following describes a basic sequence program to read and write data
to and from the AJ71C24 buffer memory.
(1) Reading data from the receive area (FROM, FROMP, DFRO, DFROP)
Data is read from the buffer memory no-protocol receive area (default:
80H
to FFH).
AJ71C24
Buffer memory (noprotocol receive area)
- - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
data storage area
j
- - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
I
(Received data read request)
(1)
Xnl
(Received data read completed) (4)
&
Y,"+,)l
. .
Xnl
(2)
Received data length read
Reads the received data length from the no-protocol received
+
data length storage area of buffer memory when the read request
signal (Xnl) is turned ON.
w-6-d
Stores
the read data length to the index register
(4.
Reads the received data of the read received data length from the
received data storage
area
of buffer memory.
(4) Read completed
Turns ON the read completed signal C/(n+l)l) after the received
+1)'
data
has
been read
Data read by program 3) is processed as the received 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 I10 numbers are allocated to 130 to 14F.
- -
- - -
- -
- + F R O M F
-
- -
- -
- -
C _
From buffer memory
- r
(area beginning with 81 H)
I
_
_ - _ - - - -
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