Boost C++ Libraries: Ticket #11721: boost::asio::serial

Boost C++ Libraries: Ticket #11721: boost::asio::serial_port bug in win10 https://svn.boost.org/trac10/ticket/11721 在最近写一些串口操作的程序时使用了 boost::asio::serial_port 来操作串口但当尝试打开串口的时候出现了错误。下面是我的测试代码： <div class="wiki-code"><div class="code"><pre>boost::asio::io_service _io_service; const std::string devname = "COM3"; try { boost::asio::serial_port serial(_io_service); serial.open(devname);// throw error every times. if (serial.is_open()) { std::cout << devname << " serial open successed." << std::endl; } else { std::cout << devname << " serial open failed!" << std::endl; } } catch (const std::exception& ex) { std::cout << ex.what() << std::endl;// GetLastError() == 87 } </pre></div></div> 每次都会出现错误87。即 <a class="missing wiki">GetLastError</a>() 的结果为 87 于是跟进代码里面调试追到了 win_iocp_serial_port_service::open 函数里 win_iocp_serial_port_service::open 函数的实现如下： <div class="wiki-code"><div class="code"><pre>boost::system::error_code win_iocp_serial_port_service::open( win_iocp_serial_port_service::implementation_type& impl, const std::string& device, boost::system::error_code& ec) { if (is_open(impl)) { ec = boost::asio::error::already_open; return ec; } std::string name = (device[0] == '\\') ? device : "\\\\.\\" + device; ::HANDLE handle = ::CreateFileA(name.c_str(), GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0); if (handle == INVALID_HANDLE_VALUE) { DWORD last_error = ::GetLastError(); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } using namespace std; ::DCB dcb; memset(&dcb, 0, sizeof(DCB)); dcb.DCBlength = sizeof(DCB); if (!::GetCommState(handle, &dcb)) { DWORD last_error = ::GetLastError(); ::CloseHandle(handle); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } dcb.fBinary = TRUE; dcb.fDsrSensitivity = FALSE; dcb.fNull = FALSE; dcb.fAbortOnError = FALSE; if (!::SetCommState(handle, &dcb)) { DWORD last_error = ::GetLastError();// lee: error is here!!! ::CloseHandle(handle); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } ::COMMTIMEOUTS timeouts; timeouts.ReadIntervalTimeout = 1; timeouts.ReadTotalTimeoutMultiplier = 0; timeouts.ReadTotalTimeoutConstant = 0; timeouts.WriteTotalTimeoutMultiplier = 0; timeouts.WriteTotalTimeoutConstant = 0; if (!::SetCommTimeouts(handle, &timeouts)) { DWORD last_error = ::GetLastError(); ::CloseHandle(handle); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } if (handle_service_.assign(impl, handle, ec)) ::CloseHandle(handle); return ec; } </pre></div></div> 发现每次在第一次 <a class="missing wiki">SetCommState</a> 的时候总是会报错并离开。于是查看了前面通过 <a class="missing wiki">GetCommState</a> 获取到的 dcb 的值。发现 dcb.<a class="missing wiki">BaudRate</a> == 0 时无法 <a class="missing wiki">SetCommState</a> 成功也就是说在有些设备中获取不到 dcb.<a class="missing wiki">BaudRate</a> 这个值。 <h2 class="section" id="下面是我自己的解决办法">下面是我自己的解决办法：</h2> 在 win_iocp_serial_port_service.ipp 文件的88行左右添加 <div class="wiki-code"><div class="code"><pre>if (dcb.BaudRate == 0) dcb.BaudRate = 115200; </pre></div></div> 修改后的 win_iocp_serial_port_service::open 函数完整代码如下： <div class="wiki-code"><div class="code"><pre>boost::system::error_code win_iocp_serial_port_service::open( win_iocp_serial_port_service::implementation_type& impl, const std::string& device, boost::system::error_code& ec) { if (is_open(impl)) { ec = boost::asio::error::already_open; return ec; } std::string name = (device[0] == '\\') ? device : "\\\\.\\" + device; ::HANDLE handle = ::CreateFileA(name.c_str(), GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, 0); if (handle == INVALID_HANDLE_VALUE) { DWORD last_error = ::GetLastError(); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } using namespace std; ::DCB dcb; memset(&dcb, 0, sizeof(DCB)); dcb.DCBlength = sizeof(DCB); if (!::GetCommState(handle, &dcb)) { DWORD last_error = ::GetLastError(); ::CloseHandle(handle); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } dcb.fBinary = TRUE; dcb.fDsrSensitivity = FALSE; dcb.fNull = FALSE; dcb.fAbortOnError = FALSE; if (dcb.BaudRate == 0) dcb.BaudRate = 115200; // add lee 2015.10.10. 解决dcb.BaudRate为0时无法成功SetCommState的BUG if (!::SetCommState(handle, &dcb)) { DWORD last_error = ::GetLastError(); ::CloseHandle(handle); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } ::COMMTIMEOUTS timeouts; timeouts.ReadIntervalTimeout = 1; timeouts.ReadTotalTimeoutMultiplier = 0; timeouts.ReadTotalTimeoutConstant = 0; timeouts.WriteTotalTimeoutMultiplier = 0; timeouts.WriteTotalTimeoutConstant = 0; if (!::SetCommTimeouts(handle, &timeouts)) { DWORD last_error = ::GetLastError(); ::CloseHandle(handle); ec = boost::system::error_code(last_error, boost::asio::error::get_system_category()); return ec; } if (handle_service_.assign(impl, handle, ec)) ::CloseHandle(handle); return ec; } </pre></div></div><h2 class="section" id="测试环境">测试环境</h2> <table class="wiki"> <tr><th> 说明 </th><th> 参数 </th></tr><tr><td> 操作系统 </td><td> Windows10 专业版 x64 </td></tr><tr><td> 开发环境 </td><td> Microsoft Visual Studio Community 2013 Version 12.0.40629.00 Update 5 </td></tr><tr><td> Boost版本 </td><td> boost_1.59.0 </td></tr></table> <h2 class="section" id="结束语">结束语</h2> 以上只是自己的猜测，并不一定是完全正确的。如有任何错误，请联系并告诉我。我将尽快修改，不胜感激。 <h2 class="section" id="我的原文">我的原文</h2> <a class="ext-link" href="http://www.leelib.com/2015/10/10/win10-boost-asio-serial-port-bug.html">http://www.leelib.com/2015/10/10/win10-boost-asio-serial-port-bug.html</a> en-us Boost C++ Libraries /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/11721 Trac 1.4.3