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MELSEC-Q
4 THE EXCHANGE BETWEEN THE PLC AND BUFFER MEMORY
(b) Word Devices
When a word device is designated in word units, one point of device
number data is stored per variable.
1
2
3
4
5
6
7
8
9
D10
D11
D12
1
2
3
4
5
6
7
8
9
A% (0)
A% (2)
A% (1)
3 words of data from
D10 is accessed
using integer
array A%( )
When an integer array is
designated, the data is stored
and set from element 0.
Data cannot be stored or set
from other than element 0.
(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
X17
b7
to
X10
b0
4
H
1
H
A
B
C
CR
1st
character
2nd
character
3rd
character
4th
character
X18 to X1F
X1F
b7
to
X18
b0
4
H
2
H
X20 to X27
X27
b7
to
X20
b0
4
H
3
H
X28 to X2B
b7 to
X28
b0
0
H
D
H
X2B
b3
to
41
H
= "A"
42
H
= "B"
43
H
= "C"
0D
H
= CR code
28 bits of data from X10
are accessed using
character variable MOJI$
8 points of device
information are stored
as character codes
Remaining each bit within one
byte that does not correspond
to the specified device
number will be set to "0."
0 1
1
0 0 0 0 0
0 1
0
0 0 0 0 1
0 1
1
0 0 0 0 1
0 0
1
0 0 1 1 0
