MODBUS_NEW_RTU(3) Libmodbus Manual MODBUS_NEW_RTU(3)NAMEmodbus_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 ALSOmodbus_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
libmodbus 3.1.0 10/06/2013 MODBUS_NEW_RTU(3)
