reading from ttyUSB0 not possible (pl2303, ch341-uart and FT232RL)

[Manfred Gruber <madmax01@xxxxxx>]

Hi,

On Ubuntu I try to access a PIC-controler via the ttyUSB0. I send a few 
command bytes and get the status from the controller. My C code works 
without problems on ttyS0 but with the usb-to-serial adapter (I tried 
tree defferent chipsets pl2303, ch341-uart and FT232RL) it just sends 
but can't read from the controller.
With minicom I can communicate with an other computer without problems 
but in my code there must be something wrong for the ttyUSB.

Any ideas what the problem could be?

Manfred

Im working on Ubuntu 9.10, Kernel 2.6.31-21


here is my code:
=====================================================
struct termios oldtio,newtio;

extern "C" HANDLE SioOpen(char *name, unsigned int baudrate)
{
BOOL RetStat;
HANDLE ComHandle;
DWORD winrate;

//Open COM port as a file
printf("Opening %s\n",name);
ComHandle = open(name, O_RDWR) | O_NOCTTY);

  if (ComHandle < 0)
      {
     printf("%s failed to open\n",name);
     perror(name);        }

 switch (baudrate) {
      case 9600:     winrate = B9600; break;
      case 19200:     winrate = B19200; break;
      case 38400:     winrate = B38400; break;
      case 57600:     winrate = B57600; break;
      case 115200:     winrate = B115200; break;
     default:        printf("Baud rate not supported - using default of 
19200\n");
                     winrate = B19200;
     }
 //printf("tcgetattr(ComHandle,&oldtio)\n");

 tcgetattr(ComHandle,&oldtio); // save current port settings

 bzero(&newtio, sizeof(newtio));

 newtio.c_cflag = winrate | CS8 | CLOCAL | CREAD;
 newtio.c_iflag = IGNPAR;
 newtio.c_oflag = 0;

 // set input mode (non-canonical, no echo,...)
 newtio.c_lflag = 0;

 // Wait block for 100ms, then timeout
 newtio.c_cc[VTIME]    = 1;   // inter-character timer unused    
newtio.c_cc[VMIN]     = 0;   // blocking read until 1 chars received
 //tcflush(ComHandle, TCIFLUSH);
 tcflush(ComHandle, TCIOFLUSH);
 //printf("tcsetattr(ComHandle,TCSANOW,&newtio)\n");
 RetStat = tcsetattr(ComHandle,TCSANOW,&newtio);

  if (RetStat < 0)
     {
     printf("Failed to set COMM configuration\n");
     //break;
     }
//printf("Setup complete, returning file handle.\n"); return(ComHandle);
}


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