Read Discrete Inputs (Command Code: 0X02) - Mitsubishi FX3U Series User Manual

FX Series Programmable Controllers
3U
User's Manual - MODBUS Serial Communication Edition
7.5

Read Discrete Inputs (Command Code: 0x02)

Reads the status (ON/OFF) of one or more inputs.
1) Request message format (Master → Slave)
2) Response message format (Slave → Master)
(When completed normally)
Function code
(When completed with an error)
*1. 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 code
Function Head input number
code (0000
H
(02 )
H
(H)
Function Number of Device data
code read bytes
(02 ) n
H
(Device data 1 to n)
b7
Device data 1
Device data n
The read input statuses are stored in order from low-order to high-order bits.
When the number of read points is not a multiple of 8, the excess bits turn to 0.
Function code
Function
code
(82
H
7.5 Read Discrete Inputs (Command Code: 0x02)
Data
Read points
to FFFF ) (0001 to 07D0
H H
(L) (H)
Data
Device data
1
(Number of read bytes n)
b6 b5 b4 b3
Data
Exception
code*
1
)
7 MODBUS Standard Commands
)
H
(L)
n
b2 b1 b0
Bit device
storage order
0 : OFF
1 : ON
1
2
3
4
5
6
7
8
9
10
51