C + + 's Asio library

1 Introduction

Asio is a cross-platform C + + library that is commonly used for network programming, low-level I/O programming, and so on (low-level I/O), with the following structural framework:

2 Using Asio

2.1 Downloads

Asio Library is divided into Boost version and non-boost version, please download it on the website.

2.2 Configuration

1) using Qt 5.9.1, in its. Pro project file, add the following configuration: note Asio_standalone must be in the Non-boost version with

Includepath + = $ $PWD/.. /.. /serialport/asio-1.10.8/includedefines + = Asio_standalone

2) Using VS 2015, the asio_standalone configuration is as follows:

2.3 Code Examples

Here is a simple serial port communication example, the main steps are: create a serial port -- configuration Parameters -- Read and write Data --turn on the event loop

#include <functional> #include "asio.hpp" #include <qdebug>using namespace asio;//store received data char kbuf[16];// Declares the callback function void Printbuf (); int main () {    //serial port COM1    io_service Iosev;    Serial_port Port (Iosev, "COM1");    Parameter settings: Baud rate, flow control, parity check, stop bit, data bit    port.set_option (serial_port::baud_rate (115200));    Port.set_option (Serial_port::flow_control (Serial_port::flow_control::none));    Port.set_option (serial_port::p arity (serial_port::p arity::none));    Port.set_option (Serial_port::stop_bits (Serial_port::stop_bits::one));    Port.set_option (Serial_port::character_size (8));    Writes data to the serial port write    (port, buffer ("Hello Asio", +));    Read data from the serial (asynchronous)    port.async_read_some (buffer (KBUF), Std::bind (PRINTBUF));    Turn on event loop    Iosev.run ();} Print received data void Printbuf () {    qdebug () << kbuf;}

3 DB9 Serial Port

When running the above program, you will find a problem: The program first to the serial port COM1, Send/write "Hello Asio" data, and then to collect/read out the data, which for a serial port, is not to receive data.

Behind the desktop, the DB9 serial pin is numbered as follows:

Among them, 2---RxD, is the pin that receives the data, 3--and TxD, is the pin that sends the data.

For the above program to run successfully, you can get 2 feet and 3 feet short before running the program , so that you can either send data or collect data

4 Virtual serial Port

If you use a notebook, there is generally no serial port, then there are two options:

First, the use of USB to serial data cable, and install the corresponding driver, you can and with the serial port of the device to communicate;

Second, use the virtual serial port software to create a virtual serial port, for example, Configure virtual Serial port Driver

Then with the serial debugging tool , you can flexibly debug the serial port program