Mitsubishi Electric QJ71MB91 User Manual page 291

Modbus interface module
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10
DEDICATED INSTRUCTIONS
(3) Request message storage devices
Device
Item
Set the size (function code + data) of the request message to be sent in byte
Request
units.
(S2)+0
message size
Set the size for transmission in the RTU mode regardless of the frame mode
(RTU mode/ASCII mode).
Set the contents (function code + data) of the request message to be sent.
Data must be stored in RTU format (binary) regardless of the frame mode
(RTU mode/ASCII mode).
(Example) When sending a request message to read the data of holding
registers 440001 and 440002 with Read Holding Registers (FC: 03)
<Frame of request message to be sent (in ASCII mode)>
(S2)+1
Request
to
message
(S2)+n
<Contents in request message storage devices and their order>
Figure 10.7 Contents in request message storage devices and their order
Table10.11 Request message storage devices
Setting data
Function code
Function code
Head holding register number
0
3
9
C
4
(33
)
(43
)
(34
(30
)
(39
)
H
H
H
H
Transmission order
(H)
(H)
(L)
(Calculated with the size for transmission in RTU mode regardless of the frame mode)
Figure 10.6 Request message example
b15
b8
b7
(S2)+0
00
H
b15
b8
b7
(S2)+1
9C
H
b15
b8
b7
(S2)+2
00
H
b15
b8
b7
(S2)+3
00
(ignored)
H
Send data storage order
(Request message is sent in order from lower-order to
higher-order bytes starting with the smallest device number.)
* 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.
Data
Read points
0
0
0
0
)
(30
)
(30
)
(30
)
(30
)
H
H
H
H
H
5 bytes
b0
Request message
05
H
size (=5 bytes)
b0
03
H
b0
40
Request message
H
b0
02
H
10.3 Z(P).MBREQ
Setting
Setting
*1
range
side
1 to 253
User
2
(32
)
H
(L)
As shown on
User
left
10
9
10
11
- 17

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