NAME

       modbus_new_rtu - create a libmodbus context for RTU

SYNOPSIS

       modbus_t *modbus_new_rtu(const char *device, int baud, char parity, int data_bit, int
       stop_bit);

DESCRIPTION

       The modbus_new_rtu() function shall allocate and initialize a modbus_t structure to
       communicate in RTU mode on a serial line.

       The device argument specifies the name of the serial port handled by the OS, eg.
       /dev/ttyS0 or /dev/ttyUSB0. On Windows, it’s necessary to prepend COM name with \\.\ for
       COM number greater than 9, eg. \\\\.\\COM10. See
       http://msdn.microsoft.com/en-us/library/aa365247(v=vs.85).aspx for details

       The baud argument specifies the baud rate of the communication, eg. 9600, 19200, 57600,
       115200, etc.

       The parity argument can have one of the following values

           •   N for none

           •   E for even

           •   O for odd

       The data_bits argument specifies the number of bits of data, the allowed values are 5, 6,
       7 and 8.

       The stop_bits argument specifies the bits of stop, the allowed values are 1 and 2.

RETURN VALUE

       The modbus_new_rtu() function shall return a pointer to a modbus_t structure if
       successful. Otherwise it shall return NULL and set errno to one of the values defined
       below.

ERRORS

       EINVAL
           An invalid argument was given.

EXAMPLE

           modbus_t *ctx;

           ctx = modbus_new_rtu("/dev/ttyUSB0", 115200, 'N', 8, 1);
           if (ctx == NULL) {
               fprintf(stderr, "Unable to create the libmodbus context\n");
               return -1;
           }

SEE ALSO

       modbus_new_tcp(3) modbus_free(3)

AUTHORS

       The libmodbus documentation was written by Stéphane Raimbault
       <stephane.raimbault@gmail.com[1]>

NOTES

        1. stephane.raimbault@gmail.com
           mailto:stephane.raimbault@gmail.com