# DFRobot_RTU

**Repository Path**: dfrobot/DFRobot_RTU

## Basic Information

- **Project Name**: DFRobot_RTU
- **Description**: No description available
- **Primary Language**: Python
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-07-21
- **Last Updated**: 2025-10-20

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# DFRobot_RTU

* [中文版](./README_CN.md)

Modbus RTU library for Arduino. The supported modbus commands are as follows：<br>
* 0x01: Read one or multiple coils register;
* 0x02: Read one or multiple discrete inputs register;
* 0x03: Read one or multiple holding register;
* 0x04: Read one or multiple input register;
* 0x05: Write a coils register;
* 0x06: write a holding register;
* 0x0F: Write multiple coils register;
* 0x10: Write multiple holding register;

![正反面svg效果图](https://github.com/Arya11111/DFRobot_MCP23017/blob/master/resources/images/SEN0245svg1.png)


## Product Link（链接到英文商城）
    
   
## Table of Contents

* [Summary](#summary)
* [Connected](#connected)
* [Installation](#installation)
* [Calibration](#calibration)
* [Methods](#methods)
* [Compatibility](#compatibility)
* [History](#history)
* [Credits](#credits)

## Summary
This is a modbus RTU libary  for Arduino by DFRobot.<br>

## Connected
Hardware conneted table 

Sensor      |               MCU                 |
------------ | :-------------------------------: |
VCC          |                5V                 |
GND          |                GND                |
RX           |connected to the UART TX pin of MCU|
TX           |connected to the UART RX pin of MCU|

## Installation

To use this library, first download the library file, paste it into the \Arduino\libraries directory, then open the examples folder and run the demo in the folder.

## Methods

```C++
/**
 * @brief DFRobot_RTU abstract class constructor. Construct serial port.
 * @param s:  The class pointer object of Abstract class， here you can fill in the pointer to the serial port object.
 * @param dePin: RS485 flow control, pull low to receive, pull high to send.
 */
DFRobot_RTU(Stream *s,int dePin);
DFRobot_RTU(Stream *s);
~DFRobot_RTU()

/**
 * @brief Set receive timeout time, unit ms.
 * @param timeout:  receive timeout time, unit ms, default 100mss.
 */
void setTimeoutTimeMs(uint32_t timeout = 100);

/**
 * @brief Read a coils Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Coils register address.
 * @return Return the value of the coils register value.
 * @n      true: The value of the coils register value is 1.
 * @n      false: The value of the coils register value is 0.
 */
  bool readCoilsRegister(uint8_t id, uint16_t reg);

/**
 * @brief Read a discrete input register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Discrete input register address.
 * @return Return the value of the discrete input register.
 */
uint16_t readDiscreteInputsRegister(uint8_t id, uint16_t reg);

/**
 * @brief Read a holding Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Holding register address.
 * @return Return the value of the holding register value.
 */
uint16_t readHoldingRegister(uint8_t id, uint16_t reg);

/**
 * @brief Read a input Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: input register address.
 * @return Return the value of the input register value.
 */
  uint16_t readInputRegister(uint8_t id, uint16_t reg);

/**
 * @brief Write a coils Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Coils register address.
 * @param flag: The value of the register value which will be write, 0 ro 1.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t writeCoilsRegister(uint8_t id, uint16_t reg, bool flag);
  
/**
 * @brief Write a holding register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Holding register address.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
uint8_t writeHoldingRegister(uint8_t id, uint16_t reg, uint16_t val);

/**
 * @brief Read multiple coils Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Coils register address.
 * @param regNum: Number of coils Register.
 * @param data: Storage register worth pointer.
 * @param size: Cache size of data.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t readCoilsRegister(uint8_t id, uint16_t reg, uint16_t regNum, uint8_t *data, uint16_t size);

/**
 * @brief Read multiple discrete inputs register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Discrete inputs register. address.
 * @param regNum: Number of coils Register.
 * @param data: Storage register worth pointer.
 * @param size: Cache size.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
uint8_t readDiscreteInputsRegister(uint8_t id, uint16_t reg, uint16_t regNum, uint8_t *data, uint16_t size);

/**
 * @brief Read multiple Holding register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Holding register.
 * @param data: Storage register worth pointer.
 * @param size: Cache size.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
uint8_t readHoldingRegister(uint8_t id, uint16_t reg, void *data, uint16_t size);

/**
 * @brief Read multiple Input register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Input register.
 * @param data: Storage register worth pointer.
 * @param regNum: register numbers.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t readInputRegister(uint8_t id, uint16_t reg, void *data, uint16_t size);

/**
 * @brief Read multiple Holding register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Holding register.
 * @param data: Storage register worth pointer.
 * @param regNum: register numbers.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t readHoldingRegister(uint8_t id, uint16_t reg, uint16_t *data, uint16_t regNum);

/**
 * @brief Read multiple Input register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Input register.
 * @param data: Storage register worth pointer.
 * @param regNum: register numbers.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t DFRobot_RTU::readInputRegister(uint8_t id, uint16_t reg, uint16_t *data, uint16_t size)

/**
 * @brief Write multiple coils Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Coils register address.
 * @param regNum: Numbers of Coils register.
 * @param data: Storage register worth pointer.
 * @param size: Cache size.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t writeCoilsRegister(uint8_t id, uint16_t reg, uint16_t regNum, void *data, uint16_t size);

/**
 * @brief Write multiple Holding Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Holding register address.
 * @param data: Storage register worth pointer.
 * @param size: Cache size.
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
uint8_t writeHoldingRegister(uint8_t id, uint16_t reg, void *data, uint16_t size);

/**
 * @brief Write multiple Holding Register.
 * @param id:  modbus device ID. Range: 0x00 ~ 0xF7(0~247), 0x00 is broadcasr address, which all slaves will process broadcast packets, 
 * @n          but will not answer.
 * @param reg: Holding register address.
 * @param data: Storage register worth pointer.
 * @param regNum: Number of coils Register..
 * @return Exception code:
 * @n      0 : sucess.
 * @n      1 or eRTU_EXCEPTION_ILLEGAL_FUNCTION : Illegal function.
 * @n      2 or eRTU_EXCEPTION_ILLEGAL_DATA_ADDRESS: Illegal data address.
 * @n      3 or eRTU_EXCEPTION_ILLEGAL_DATA_VALUE:  Illegal data value.
 * @n      4 or eRTU_EXCEPTION_SLAVE_FAILURE:  Slave failure.
 * @n      8 or eRTU_EXCEPTION_CRC_ERROR:  CRC check error.
 * @n      9 or eRTU_RECV_ERROR:  Receive packet error.
 * @n      10 or eRTU_MEMORY_ERROR: Memory error.
 * @n      11 or eRTU_ID_ERROR: Broadcasr address or error ID
 */
  uint8_t writeHoldingRegister(uint8_t id, uint16_t reg, uint16_t *data, uint16_t regNum);
```

## Compatibility

MCU                | SoftwareSerial | HardwareSerial |
------------------ | :----------: | :----------: |
Arduino Uno        |      √       |      X       |
Mega2560           |      √       |      √       |
Leonardo           |      √       |      √       |
ESP32              |      X       |      √       |
ESP8266            |      √       |      X       |
micro:bit          |      X       |      X       |
FireBeetle M0      |      X       |      √       |
raspberry          |      X       |      √       |

## History

- Data 2021-07-17
- Version V1.0

## Credits

Written by(xue.peng@dfrobot.com), 2021. (Welcome to our [website](https://www.dfrobot.com/))