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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.7.3 Batch read in units of words
The method for specifying the control protocol and examples are shown
below for a batch read of word device memory and batch read of bit device
(
memory (1 6-point units).
(a) Using the WR command (ACPU common command)
)esignation Method
1
St. No. :Station number
Designation in protocol 1 is shown below.
Character
area A
Character area
B
~
~
~~~~
~~~~~
~
1 point of the device uses 4 characters.
I
To designate the device range, the following conditions must be met:
I
I
1
5
number of device points
5
64 (32 for a bit device)
I
I
s t
No.
HlL
(Head device number)
+
[(number of device points** )
-
I ]
5
maximum
device number
I
**
("number of device points" x 16 for a bit device)
I
AJ71 C24
/
Designation of device
Batch read (word)
range to be read
command
I
PC
No.
H l L
Therefore, a 1-word data is expressed
in 4 digits (hexadecimal).
I
Example 1:
To read data at 32 points from X40 to X5F in station "5".
(Message wait time is 0 msec)
A
s
Computer
I
I
5 F F W R O X O O 4 0
Check sum is calculated
within this range
I U H ~ ~ ~ & Y " I S ~ *
YD.
%~*IX~.Y*,Y*~~"
7
~
.
.
Check sum is calculated
S
I
E
T
0 5 F F 1 2 3
4 i A B C D
T
C 8
within this range
x
i
X
m .
~.,~.~~.,~.~~.,P.,UU,YY,~~W,~~~,~JJJUU
UH
U.,Y.
I
I
s t
NO.
H I L
I
NO
HI L
1
2
1
3
I
4
A
I
B
I
C
I
D
X
X
X
X X X X X X X
. .
.
. . . . . . . . . . . . . . . . .
X X X X
4
4
4
4
4
4
4
5
5
5
. . . . . . . . . . . . . . . . . . . .
5
5
5
5
F E D
3
2
1
0
F
E
D
3
2
1
0
Messgage
watime
I
PC
NO.
HlL
The WR command is used for word unit designation. The designation for
32 points of devices from X40 t o X5F is "02" ( " I "
for 16 points).
I
PC
NO.
HI
L
I I I I
Head den,
(5charaderr)
1 1 1 1
Data of
me
designated number of
devi,
(characterrforthe
designated number of
device points)
I
Numberof
(2charanerr
(hexadecimal)
H I
L
I
chesk
'Ode
H I L
i
Sum
' 2 ;
H I L
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