Mitsubishi Electric AJ71C24-S6 User Manual page 137

8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.6
Character Area Data Transmission
The concept of transmission data handled as character areas when using
commands to carry out data communications between the computer and the
PC CPU is explained in this section. The data shown in the examples is
contained in character area B in the case of read and monitor, and in
character area C in the case of write, test, and monitor data register.
(1) Bit device memory read and write
The bit device memory can be handled in bit units (1 device point) or
word units
(16
device points).
These units are described below.
(a) Bit units (1 point)
When the bit device memory is handled as bit units, the specified
number of device pointsfrom the specified head device in sequence
from the left are represented as 1 (31H) if the device is ON, or
0
(30H) if the device is OFF.
Example: lndication of the ONIOFF status of
5
points from M l O
lndicatesthat M I 4 is ON
Indicates that M I 3 is OFF
Indicates that M I 2 is ON
Indicates that M I 1 is OFF
lndicatesthat M I 0 is ON
(b) Word units (16 points)
When the bit device memory is handled as word units, each word
is expressed sequentially in hexadecimal values in 4-bit units from
the higher bit.
Example: lndication of the ONIOFF status of 32 points from
M16
Number of device points is " 0 2 because
memory is used in units o f word.
0 : represents ON
1 : represents OFF
Head devtce
4DH130H130H131H136H
1 0 1 1 1 0
,
,
,
A 2 3 4 C
"
. I
'iI5
B14*813 812'811 810 89 88
'
87
B6
85
84 ' 8 3
82
B l
BO
'815 814 813 812'811 810 89
88
'
87 86 85 84
'
83 82 81 80
N"L
of devlce
points
30H132H
M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M
31
30 29
28
27
26
25
24
23
22
21
20 3 9
I S 37
16
47 46
45 01 43 42 41 40
39
j a
37
36
35
34 33 32
1 1 1 1 1 1 1
Data Data
M O 0 1 6 0 2 A B i 2 8 3 4 C D
41H142H131H132H133Hl34HI43HlMH
5
O l O l l l i , 1 0 1 1 1 ,
, , ,
O l D i O l , l l i l O l l
O , O i l 1 0 0 1 1 , 0 1 0
l l l l O l 0