Chapter 5 Introduction To Modbus Rtu Commands; Read Coil Status - Ebyte E150-400T30S User Manual

Chengdu Ebyte Electronic Technology Co.,Ltd.

Chapter 5 Introduction to Modbus RTU Commands

Modbus RTU has a total of 8 function codes (hexadecimal), and their meanings are as follows:
function code
01

Read coil status

02 Read discrete input
03 read holding register
04 read input register
E150-400T30S modules can communicate with E22-400Txxx series modules wirelessly, but the following
conditions must be met:
Both modules need to work in "transparent mode";
The parameters of "air rate", "channel address", "module address" and "network number" of both modules
must be consistent;
The following commands related to remote wireless communication must meet the above conditions.
5.1 Read coil status
Using the read coil status (01) function code to read the output coil status, for example: read the status of
do1 ~ do4
01
Device MODBUS Function code
address
CRC check code note: the CRC check code of the last two bytes of the sending instruction needs to be calculated
by the user.
Serial port sending: 01 01 00 00 04 3D C9
Remote wireless transmission: 01 01 00 00 00 04 3D C9
After the above command is sent to the device through the serial port or wireless, the device will return the
following values to the serial port or wireless:
01
Device MODBUS Function code
address
The returned status data 0f indicates that the outputs do1 to do4 are at a high level.
Serial port receiving return value: 01 01 01 0f 11 8C
Copyright ©2012–2022，Chengdu Ebyte Electronic Technology Co.,Ltd.
illustratation
01 00 00
Register
head address
01 01
Number of
bytes of data
function code
05 write coil status
06 write a single register
0F write multiple coils
10 write multiple registers
00 04
Number of output
coils read
0F
Returned status
data
E150-400T30S user manual
illustration
3D C9
CRC check
code
11 8C
CRC check
code
10