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
0350
and
D351
registers
Numk
of
device
points
k
TQ"
becaw
memory
is
used
in units
d
word.
mInn
1
IIII
Hadm
dd.v(o
Nl&
pahb
I
003502556AB117DF
1
5
I
6
I
A
I
8
I
1
I
7
I
0
I
F
4
815 814
813
812 811 810
88
m
B7
W
BS
B4
E3
E?
81
80
615 814 813 812 Bl1 810
88
BB
81
BB
Bs
84
53
82
81
80
0111011
lI11111
OlOlOlO
0111111 1101111 0101011 1101110
0111110
Ill
,I,
111
Ill
11,
(I1
Ill
Ill
,It
I,,
111
I,
111
I,!
,I
!I,
REMARK^
(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 computer to
the
PC CPU,
the processing should
be as shown below:
1)
The character-string to
be
transmitted is developed into 2-byte
codes in units of characters.
Example: To transmit
'1 8AFH
to a sequence program.
'1
'8"
'A"
'F"
'H"
"C
I
R
Coder
.....
31H 38H
41
H 46H
48H
ODH
S3H
AAAAAA
31H
33H
38H 34H 31H 34H 36H 34H
38H
W-i
44H
3.
'1"
y$"
'4"
y"
'4"
w.
'4"
'o"
'D"
2)
The character-string developed into 2-byte codes is arranged in
units of
2
characters and sent to the
AJ71C24.
Example: The character-string used
in
the above example in
1.
"31 38 41 46 48
OD"
"383146410D48"
uun
'3831 4641 OD48"
is
sent from the computer to the
AJ71 C24.
,e-
.
'-
--
c
c
c
8-20
i
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