open_source / modbus

  #pragma once

  #include <stdint.h>

  #include <termios.h>

  
  #define _MODBUS_RTU_HEADER_LENGTH      1
  #define _MODBUS_RTU_PRESET_REQ_LENGTH  6
  #define _MODBUS_RTU_PRESET_RSP_LENGTH  2
  
  #define _MODBUS_RTU_CHECKSUM_LENGTH    2
  

  typedef struct _modbus_rtu
  {

      /* Device: "/dev/ttyS0", "/dev/ttyUSB0" or "/dev/tty.USA19*" on Mac OS X. */
      char *device;
      /* Bauds: 9600, 19200, 57600, 115200, etc */
      int baud;
      /* Data bit */
      uint8_t data_bit;
      /* Stop bit */
      uint8_t stop_bit;
      /* Parity: 'N', 'O', 'E' */
      char parity;

      /* Save old termios settings */
      struct termios old_tios;

  #if HAVE_DECL_TIOCSRS485
      int serial_mode;
  #endif

      /* To handle many slaves on the same link */
      int confirmation_to_ignore;
  } modbus_rtu_t;