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8. COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
(2) Word device memory read and write
In the word device memory, each word is expressed sequentially in
hexadecimal values in 4-bit units from the higher bit.
Example:
Indication of the contents of the D350 and D351 registers
nacalcs that the content of rcgister
0350
:s
56ABrl(22187 'n decimal)
Number of device points is "02"
because memory is used in units of word.
Indicates that the content of register
D351 is 170FH (5903 in decimal)
I
I
I
I
Head device
MH130H133H135H13oH
(1) Extension file memory read and write, buffer memory read and write,
and on-demand data when word units are specified are handled ac-
cording to the same principle as the word device memory.
(2)
To output a character-string with the PR instruction externally after
transmitting it from the computerto the PC CPU, the processing should
be as shown below:
I
I
Number
04dsvice
Pain*
30H132H
1) The character-string to be transmitted is developed into 2-byte
codes in units of characters.
I
I
I
I
I
I
I
~ a t a
oata
D
0
3
5
0
2
5
5
6
A
8
'
1
7
0
F
J5H136H141H142H131Hl37HI30HI46H
\ \ h
I .
5
6
I
A
1 .
8
I
1
1
7
0
F
815 814 813 812 811 810
69
BB
87
B6 65
84
83
82
81
BO
815 814 813 812 811 810
69
BB
87
BB
ffi
84
83
82
81
80
Example: To transmit "18AFH
' R "
to a sequence program.
"1'
"8"
"A"
',F"
" H
,C
R((
Codes
.....
(
33H
31H
33H
38H
34H
31H
34H
36H
34H
38H
30H
44H
O I t I O I ,
"3"
"3"
u 8 "
"4"
","
"4"
"6"
m4',
',0"
"D"
2) The character-string developed into 2-byte codes is arranged in
units of 2 characters and sent to the AJ71 C24.
O I 1 1 l 1 0
0 1 0 1 0 1 l
Example: The character-string used in the above example in 1.
0 1 , 1 1 1 ,
0 1 0 1 0 l O
"31 38 41 46 48 OD"
"383146410D48"
ffun
"383146410D48" is sent from the computer to the AJ71C24.
1 1 O l l 1 0
l i 1 l l l l
l I O i 1 1 1
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