MODBUS++ (MODBUSPP) is an open source c++ class/ library making an encapsulation of Modbus TCP Protocol published by Modicon (Now Schneider Electirc).

MODBUS++ is based on Object-Oriented Programming. While it keeps the efficiency of C++ Code , it provides a higher level of abstraction than other C Modbus Library. Generally, it is easier for programmers to use in their development requiring MODBUS TCP Protocol. Compared to other known modbus library, such as libmodbus, MODBUS++ is providing a more OOP friendly syntaxes.

The code has dependencies on libary on Linux for TCP/IP, if you want to use this in Windows, please check out winsock2 and rewrite portion of code of socket to be compatible with Windows operating system.

To use the library, please follow the steps below. Please note current library is only compatible with Linux distributions because of the socket library dependencies.

Download the MODBUS++, you can:

• Open your command window (cmd, shell, bash, etc.)

git clone https://github.com/fanzhe98/modbuspp.git

• Directly Download From the Page

To include Modbus++ in your code, just simply type this in the start of your program:

include "modbus.h" include "modbus_exception.h"

Please checkout example.cpp for a example usage of MODBUSPP. Please note that the code should be compiled using c++11 compilers.

Include the header

#include "modbus.h" This line includes the header modbus.h from the library, this will tell the compiler to look for functions and variables in the related file.

Create and connects a mobus server

modbus mb = modbus("127.0.0.1", 502); mb.modbus_set_slave_id(1); mb.modbus_connect(); These lines creates local modbus client with target IP address at 127.0.0.1 and port at 502, a server with id 1.

Read a coil (function 0x01)

bool read_coil; mb.modbus_read_coils(0, 1, &read_coil); These lines read a bit from the coil at address 0.

Read input bits(discrete input) (function 0x02)

bool read_bits; mb.modbus_read_input_bits(0, 1, &read_bits); These lines read a bit from discrete inputs at address 0.

Read holding registers (function 0x03)

uint16_t read_holding_regs[1]; mb.modbus_read_holding_registers(0, 1, read_holding_regs); These lines read a word(16 bits) from holding registers starting at address 0.

Read input registers (function 0x04)

uint16_t read_input_regs[1]; mb.modbus_read_input_registers(0, 1, read_input_regs); These lines read a word(16 bits) from input registers starting at address 0.

Write single coil (function 0x05)

mb.modbus_write_coil(0, true); These lines write a bit to the coil at address 0.

Write single reg (function 0x06)

mb.modbus_write_register(0, 123); These lines write a word(16 bits) to the register at address 0.

Write multiple coils (function 0x0F)

bool write_cols[4] = {true, true, true, true}; mb.modbus_write_coils(0,4,write_cols); These lines write multiple bits to the coil starting from address 0, for a length of 4.

Write multiple regs (function 0x10)

uint16_t write_regs[4] = {123, 123, 123}; mb.modbus_write_registers(0, 4, write_regs); These lines write multiple words to the register starting from address 0, for a length of 4.