libmodbus/doc/modbus_new_rtu.txt

modbus_new_rtu(3)
=================


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
-------
[source,c]
-------------------
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
--------
linkmb:modbus_new_tcp[3]
linkmb:modbus_free[3]


AUTHORS
-------
The libmodbus documentation was written by Stéphane Raimbault
<stephane.raimbault@gmail.com>