Hey all,

I'm trying to write to a serial device using QextSerialPort. Here are some things I should note:

*I can read from the device, but cannot write to it.
*I can read and write from the device using a serial communication tool (cutecom)
*Using a loopback serial cable, I can see that write is working

Based on this info, I know it seems like the problem is device related, and for what its worth, it seems to have a really flaky serial I/F. However, I've been able to use it with normal linux serial drivers, and I can communicate with the device with cutecom (a linux gui app that r/w to serial ports -- handy for testing) no problem. This leads me to believe I'm doing something wrong with QextSerialPort that I don't understand. I made a simple program similar to the "events" example included with the source.

I'd really appreciate any advice!

-KF


Qt Code: 
  1. //	System Includes
  2. #include "main.h"
  3.  
  4. // RS232 Helper Thread
  5. RS232Thread::RS232Thread(QextSerialPort* port, QObject* parent)
  6. 	:QThread(parent)
  7. {	serialPort = port;	}
  8.  
  9. RS232Thread::~RS232Thread()
  10. {}
  11.  
  12. void RS232Thread::run()
  13. {
  14. 	// constantly get user input
  15. 	std::string inpSt;
  16.  
  17. 	std::cerr << "Send MVP a command string: " << std::endl;
  18.  
  19. 	while (inpSt.compare("quit") != 0)
  20. 	{
  21. 		std::getline(std::cin, inpSt);
  22. 		std::cerr << serialPort->write(inpSt.c_str());
  23.         std::cerr << "Sent command: " << inpSt << std::endl;
  24. 	}
  25.  
  26. 	serialPort->close();
  27. }
  28.  
  29.  
  30. // RS232 Signal Handler
  31. RS232SignalHandler::RS232SignalHandler(QextSerialPort* port, RS232Thread* thread, QObject* parent):
  32. 	QObject(parent)
  33. {	serialPort = port;
  34. 	sTime = thread->startTime;	}
  35.  
  36. RS232SignalHandler::~RS232SignalHandler()
  37. {}
  38.  
  39. void RS232SignalHandler::RS232ReceivedData()
  40. {
  41.  
  42. 	char data[512];
  43. 	int numBytesRead = serialPort->read(data, 512);
  44.  
  45. 	std::cerr << "DATA READ IN: " << std::endl;
  46.  
  47. 	// print out what we read in as chars
  48. 	for (int i=0; i < numBytesRead; i++)
  49. 	{	std::cerr << data[i];	}
  50. 	std::cerr << std::endl;
  51.  
  52. 	// print out what we read in as ints
  53. 	for (int i=0; i < numBytesRead; i++)
  54. 	{	std::cerr << int(data[i]);	}
  55. 	std::cerr << std::endl;
  56. }
  57.  
  58.  
  59. //	Start Main
  60. int main(int argc, char *argv[])
  61. {
  62.     QCoreApplication a(argc, argv);
  63.  
  64.     // set up serial port
  65.     QextSerialPort *port = new QextSerialPort("/dev/ttyUSB0", QextSerialPort::EventDriven);
  66.     port->setBaudRate(BAUD9600);
  67.     port->setFlowControl(FLOW_OFF);
  68.     port->setParity(PAR_NONE);
  69.     port->setDataBits(DATA_8);
  70.     port->setStopBits(STOP_1);
  71.  
  72.     // setup helper thread
  73.     RS232Thread* hThread = new RS232Thread(port);
  74.     a.connect(hThread, SIGNAL(finished()), &a, SLOT(quit()));
  75.     hThread->start();
  76.  
  77.     // setup data received signal handler
  78.     RS232SignalHandler* handler = new RS232SignalHandler(port, hThread);
  79.     handler->connect(port, SIGNAL(readyRead()), handler, SLOT(RS232ReceivedData()));
  80.  
  81. 	// event loop
  82.     return a.exec();
  83. }
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