10 - 14 10 - 14
MELSEC-Q
10 DEDICATED INSTRUCTIONS
Response message storing devices
Device Item
Set
Data
Setting
Range
Setting
Side
*1
(D1)+0
Response
message size
[byte]
Set the size of the received response message in byte units.
0 to 253
System
(D1)+1
to
(D1)+n
Response
message
Set the contents (function code + data) of the received response message.
(Example) When the response message with Read holding registers (FC: 03) is
received
<Received response message frame>
(H)
(L)
(H)
(L)
03
H
04
H
*
2
00
H
05
H
12
H
34
H
Function code
Data
6 bytes
Function code Number of read
bytes
Device data
1
Device data
2
Receiving order
<Contents stored in response message storing devices and their order>
b0
b15
b7
b8
b0
b15
b7
b8
b0
b15
b7
b8
b0
b15
b7
b8
00
H
06
H
04
H
03
H
05
H
00
H
34
H
12
H
<(D1) + 0>
<(D1) + 1>
<(D1) + 2>
<(D1) + 3>
Response message size
(= 6 bytes)
Response message
(Response message is stored in order of low-
order to high-order bytes, starting at the lowest
device number.)
Received data storage order
As described
on the left
System
*1: The setting side is as described below.
User: Data are set by the user before dedicated instruction execution.
System: The programmable controller CPU stores the result of dedicated
instruction execution.
*2: The number of read bytes is 4 from "2 (Read points) 2 = 4".
POINT
(1) The received response message data are stored in order of L (low-order) to H
(high-order) bytes, starting at the lowest device number of the response
message storing devices "(D1)+1 to (D1)+n".
(2) When the response message size is an odd number, the last high byte of the
response message storing device is overwritten by 0.
