Read Coils (Command Code: 0X01) - Mitsubishi FX3U Series User Manual

FX Series Programmable Controllers
3U
User's Manual - MODBUS Serial Communication Edition
7.4

Read Coils (Command Code: 0x01)

Reads the status (ON/OFF) of one or more coils.
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.
50
Function code
Head coil number
Function
(0000 to FFFF
code
H
(01 )
H
(H)
Function Number of Device data
code read bytes
(01 ) n
H
(Device data 1 to n)
Device data 1
Device data n
The read coil 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
Data
Read points
) (0001
H H
(L) (H)
Data
Device data
1
(Number of read bytes n)
b7 b6 b5 b4 b3
Data
Exception
(81 ) code* 1
H
7 MODBUS Standard Commands
7.4 Read Coils (Command Code: 0x01)
to 07D0 )
H
(L)
n
b2 b1 b0
Bit device
storage order
0 : OFF
1 : ON