Read Input Registers (Command Code: 0X04) - Mitsubishi FX3U Series User Manual

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FX
Series Programmable Controllers
3U
User's Manual - MODBUS Serial Communication Edition
7.7

Read Input Registers (Command Code: 0x04)

Reads the values of one or more input registers.
1) Request message format (Master → Slave)
Function code
2) Response message format (Slave → Master)
(When completed normally)
Function code
Function
code
(04
)
H
(When completed with an error)
*2. Exception and error codes are stored in special data registers and special auxiliary relays in the case
of error completion. Refer to Chapter 6 for storage location, confirmation methods, and other detailed
contents.
Function
Head input register number
code
(0000
to FFFF
H
(04
)
H
(H)
Device data
Number of
1
read bytes
m = n x 2*
1
(H)
Function code
Function
code
(84
)
H
7.7 Read Input Registers (Command Code: 0x04)
Data
Read points
)
(0001
to 007D
H
H
(L)
(H)
(L)
Data
. . .
Device data
(L)
(H)
(Number of read bytes n x 2)
*1 For example, if n = 4, the number of bytes is
calculated as 4 x 2 = 8 bytes
Data
Exception
code *
2
7 MODBUS Standard Commands
)
H
n
(L)
1
2
3
4
5
6
7
8
9
10
53

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