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4 THE EXCHANGE BETWEEN THE PLC AND BUFFER MEMORY
4 - 16
(b) Word Devices
When a word device is designated in word units, one point of device
number data is stored per variable.
D10
1
2
3
D11
4
5
6
3 words of data from
D12
7
8
9
D10 is accessed
using integer
array A%( )
(2) When character variables and character array variables are used
as data storage area
(a) Bit Device
Bit units are handled in the same manner as (1), and they are handled in bit
units and word units.
• Bit units
The data read during bit unit designation considers eight points of
ON/OFF data for the device number as a single JIS8 code. The data for
the number of devices designated is stored using characters compatible
with the JIS8 code.
Therefore, the amount of data required for storing and setting the amount
of data designated in the number of process points to the elements are
as follows.
The number of character data = Number of Process Points/8 (Decimals
are rounded up)
The status of the each bit is "0" when the corresponding device is OFF
and "1" when it is ON.
X10 to X17
X18 to X1F
X20 to X27
X28 to X2B
Remaining each bit within one
byte that does not correspond
to the specified device
number will be set to "0."
A% (0)
A% (1)
A% (2)
28 bits of data from X10
are accessed using
X17
X10
character variable MOJI$
b7
to
b0
0 1
0 0 0 0 0
1
4
1
H
H
X1F
X18
to
b7
b0
0 1
0 0 0 0 1
0
4
2
H
H
X27
X20
to
b0
b7
0 1
0 0 0 0 1
1
4
3
H
H
X2B
X28
b7 to
b3
to
b0
0 0
0 0 1 1 0
1
0
D
H
H
1
2
3
When an integer array is
designated, the data is stored
4
5
6
and set from element 0.
Data cannot be stored or set
7
8
9
from other than element 0.
8 points of device
41
= "A"
H
information are stored
as character codes
42
= "B"
H
43
= "C"
H
0D
= CR code
H
A
B
C
1st
2nd
3rd
character
character
character
character
MELSEC-Q
CR
4th
4 - 16
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