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A Modbus library for Linux, Mac OS X, FreeBSD, QNX and Win32

libmodbus is a free software library to send/receive data according to the Modbus protocol. This library is written in C and supports RTU (serial) and TCP (Ethernet) communications.

The license of libmodbus is LGPL v2.1+ and the licence of programs in the tests directory is BSD 3-clause.

The documentation is provided with libmodbus releases as man pages (generated from doc sources). You can also browse the documentation of the different releases of libmodbus:

See the Wiki for general informations.

Code Sample

  modbus_t *mb;
  uint16_t tab_reg[32];

  mb = modbus_new_tcp("", 1502);

  /* Read 5 registers from the address 0 */
  modbus_read_registers(mb, 0, 5, tab_reg);


External Documentation