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4 THE EXCHANGE BETWEEN THE PLC AND BUFFER MEMORY
PLC CPU Device
44
H
D1
(H)
31
H
D2
(H)
0D
H
D3
(H)
4 - 21
• For character data
41
H
(L)
35
H
(L)
FROM
48
H
/TO
(L)
Accessed using
(
address 10
H
through 12
H
PLC CPU Side
The PUTMEM and GETMEM instructions are used in common memory and while sharing
access of internal devices (ED).
Note that when addresses 1800h through 7FFFh (viewed from BASIC) are used,
the process will be performed on the common memory and internal device.
• When reading data with the GETMEM instruction, the following illustrates if a
character data greater than the character variable specified as readout variables or
number of bytes to be read in the character array variables (one byte = one
character) is stored.
When RD$ is used as the readout variable
RD$
. M. I. T. S. U. B. I. S. H. I.
. A. D. 5. 1. H.
Readout data
RD$
. A. D. 5. 1. H. B. I. S. H. I.
REMARK
Access • • • A collective term for I/O processing such as reading and writing data.
Buffer Memory
RD $
41
= "A"
H
41
(L)
20
H
H
10
44
H
44
(H)
21
H
H
35
(L)
22
H
H
11
H
31
(H)
23
H
H
48
(L)
24
H
H
12
H
0D
(H)
25
H
H
)
GETMEM
/PUTMEM
AD51H-BASIC Side
Stores the value of the buffer
memory using character codes.
Readout execution
Data before the readout
execution will be stored
MELSEC-Q
Character Variables, Character Array Variables
3rd
4th
1st
2nd
character
character
character
character
A
D
5
1
="D"
H
35
= "5"
H
31
= "1"
H
48
= "H"
H
0D
=CR code
H
Accessed using
(
address 20
through 25
5th
6th
character
character
H
<CR>
)
H
H
4 - 21
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