modbus_rtu_set_serial_mode - set the serial mode
int modbus_rtu_set_serial_mode(modbus_t
*ctx, int mode);
The modbus_rtu_set_serial_mode() function shall set the
selected serial mode:
MODBUS_RTU_RS232
the serial line is set for RS232 communication. RS-232
(Recommended Standard 232) is the traditional name for a series of standards
for serial binary single-ended data and control signals connecting between a
DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment).
It is commonly used in computer serial ports
MODBUS_RTU_RS485
the serial line is set for RS485 communication. EIA-485,
also known as TIA/EIA-485 or RS-485, is a standard defining the electrical
characteristics of drivers and receivers for use in balanced digital
multipoint systems. This standard is widely used for communications in
industrial automation because it can be used effectively over long distances
and in electrically noisy environments.
This function is only supported on Linux kernels 2.6.28
onwards.
The function shall return 0 if successful. Otherwise it shall
return -1 and set errno to one of the values defined below.
EINVAL
The current libmodbus backend is not RTU.
ENOTSUP
The function is not supported on your platform.
If the call to ioctl() fails, the error code of ioctl will be
returned.
The libmodbus documentation was written by Stéphane
Raimbault <stephane.raimbault@gmail.com>