'\" t
.\"     Title: modbus_rtu_get_serial_mode
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 02/28/2020
.\"    Manual: libmodbus Manual
.\"    Source: libmodbus v3.1.6
.\"  Language: English
.\"
.TH "MODBUS_RTU_GET_SERIA" "3" "02/28/2020" "libmodbus v3\&.1\&.6" "libmodbus Manual"
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.SH "NAME"
modbus_rtu_get_serial_mode \- get the current serial mode
.SH "SYNOPSIS"
.sp
\fBint modbus_rtu_get_serial_mode(modbus_t *\fR\fB\fIctx\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
The \fBmodbus_rtu_get_serial_mode()\fR function shall return the serial mode currently used by the libmodbus context:
.PP
\fBMODBUS_RTU_RS232\fR
.RS 4
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
.RE
.PP
\fBMODBUS_RTU_RS485\fR
.RS 4
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\&.
.RE
.sp
This function is only available on Linux kernels 2\&.6\&.28 onwards and can only be used with a context using a RTU backend\&.
.SH "RETURN VALUE"
.sp
The function shall return MODBUS_RTU_RS232 or MODBUS_RTU_RS485 if successful\&. Otherwise it shall return \-1 and set errno to one of the values defined below\&.
.SH "ERRORS"
.PP
\fBEINVAL\fR
.RS 4
The current libmodbus backend is not RTU\&.
.RE
.SH "AUTHORS"
.sp
The libmodbus documentation was written by Stéphane Raimbault <stephane\&.raimbault@gmail\&.com>