Hello all, I am having trouble getting asio serial ports to work. Specifically when I call boost::asio::async_read, it immediately calls the read completion handler with error EINVAL aka Invalid argument. Please help! I have invested significant time in asio serial ports! Mac OSX 10.6.4 GCC 4.2.1 boost version 1.44.0 The test case console output: $ ./test ERROR 22 Invalid argument $ The test case code: #include <iostream> #include <cstdlib> #include <vector> #include #include const int HeaderSize = 2; std::vector<char> ReadVector; void ReadHandler(const boost::system::error_code& error, std::size_t bytes_transferred) { if (error) { std::cout << "ERROR " << error.value() << " " << error.category().message( error.value()) << std::endl; return; } else { std::cout << "Bytes Received" << std::endl; } } int main () { ReadVector.resize(2000); boost::asio::io_service SerialService; boost::asio::serial_port SerialPort(SerialService, "/dev/tty.usbserial-FTCW1RJN"); boost::asio::serial_port_base::baud_rate baud_option(115200); SerialPort.set_option(baud_option); assert(SerialPort.is_open()); boost::asio::async_read(SerialPort, boost::asio::buffer(ReadVector, HeaderSize), boost::bind(&ReadHandler, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); SerialService.run(); } -- Whitham D. Reeve II 907-764-5263