9.
COMMUNICATIONS IN THE NO-PROTOCOL
MODE
MELSEC-A
9.4
Basic Program
to
ReadMlrlte Buffer Memory
.-
"1
il
I
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).
PC
CPU
nm
-?
LB
4
J
n
(1)
Read
request
(2)
Fkceiied
data
kngth
read
Reads
ttte
received
dda
length
from
the
mprotccol
r&d
I
FROMP
I
nl
I
data
kngth
storage
area
d
buffer
when
the
read
I'Oqwst
signal (Xnl)
is
tu&
ON.
1
MWmF
stores
the
read data
kngth
to
the
index
regi8ter
(2).
(3)
Received
data read
Readsthe receiveddataoftheread
received
ddalengthfromthe
received
data storage area
of
buffer memory.
(4)
Read completed
Tums
ON
read
completed
signal (Y(n+l)l)
&or
the received
Data
read
by
program
3)
is
processed
as
the
received
data
9
I.1
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.
L
I
-it
X1
31
I
FROMP
]H13/WI
W
I
K1
d
n
a
L
--
1
I
1
L
9-6
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