[Rxtx] RTS_CONTROL question

[Adrian Stan]

Hello,

I am an user of RXTX library (through Eclipse RSE Terminal).
I have an issue related to reading from a serial device. At some point, I cannot read anymore, even if data is available.
The problem is not reproducible with Putty, which reads fine till the end.
I have debugged the problem and seems to be located into function termios_to_DCB(), in file termios.c
Here, we have the following piece of code:

if ( s_termios->c_cflag & HARDWARE_FLOW_CONTROL )
{
dcb->fRtsControl = RTS_CONTROL_HANDSHAKE;
dcb->fOutxCtsFlow = TRUE;
}
else
{
dcb->fRtsControl = RTS_CONTROL_DISABLE;
dcb->fOutxCtsFlow = FALSE;
}

Here, if RTS/CTS is disabled, we are setting dcb->fRtsControl = RTS_CONTROL_DISABLE, which doesn't look right.

Maybe it should remain set to RTS_CONTROL_ENABLE.

I have modified the code accordingly:
if ( s_termios->c_cflag & HARDWARE_FLOW_CONTROL )
{
dcb->fRtsControl = RTS_CONTROL_HANDSHAKE;
dcb->fOutxCtsFlow = TRUE;
}
else
{
dcb->fOutxCtsFlow = FALSE;
}

After the modification, I could read successfully from the serial device, no more issues were encountered.

I have looked in the source code of Putty, to see how they are dealing with this situation.
The relevant piece of code is in function serial_configure(), in file WINSERV.c (from Putty source code)

static const char *serial_configure(Serial serial, HANDLE serport, Config *cfg)

{
...
 DCB dcb;

...
dcb.fRtsControl = RTS_CONTROL_ENABLE;

...
switch (cfg->serflow) {
  case SER_FLOW_NONE:
    str = "no";
    break;
  case SER_FLOW_XONXOFF:
    dcb.fOutX = dcb.fInX = TRUE;
    str = "XON/XOFF";
    break;
  case SER_FLOW_RTSCTS:
    dcb.fRtsControl = RTS_CONTROL_HANDSHAKE;
    dcb.fOutxCtsFlow = TRUE;
    str = "RTS/CTS";
    break;
  case SER_FLOW_DSRDTR:
    dcb.fDtrControl = DTR_CONTROL_HANDSHAKE;
    dcb.fOutxDsrFlow = TRUE;
    str = "DSR/DTR";
    break;
}
...
}

So, Putty sets dcb.fRtsControl to RTS_CONTROL_HANDSHAKE if  RTS/CTS is enabled, but leaves it set to  DTR_CONTROL_ENABLE if  RTS/CTS is NOT enabled.

Any input on this issue is highly appreciated.

Thanks for your help,
Adrian
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