DTR Flow Control

lawson_whitney at juno.com lawson_whitney at juno.com
Fri Feb 22 21:07:43 CST 2002

On Fri, 22 Feb 2002, Michael Cardenas wrote:

> Is DTR flow control supported?

I am not at all sure, because I don't know what it is.  Hardware flow
control as understood by the Linux C library is rts/cts flow control.
> There's a comment in comm.c in SetCommState that says it's not, but
> EscapeCommFunction has a SETDTR case and a CLRDTR case.
No necessary connection.  The app can manipulate those signals itself.
Flow control as I understand it is done by the modem and the OS to
prevent overrun of the FIFO and the OS's buffers, behind the app's back,
so to speak.

> Below are the lines I'm talking about.
> I'm working on an app that asks for DTR flow control and uses overlapped
> IO when using a modem. It establishes a modem connection, but then it
> can't send any data over the connection. I'm using an external modem on
> a serial port.
Probably a logfile from

wine --debugmsg +file,+comm yourapp.exe 2>&1 | tee logfile

would mean more to me than excerpts from code I help maintain.  +relay
never hurts, except it takes so much space, but traces gzip pretty well.
I expect Mike McCormack, the other person who is willing to touch Wine
serial comms, will be along presently.



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