Re: Correction: Serial port arbitration
Re: Correction: Serial port arbitration
- Subject: Re: Correction: Serial port arbitration
- From: Gregory Weston <email@hidden>
- Date: Fri, 8 Apr 2005 15:24:33 -0400
On Apr 8, 2005, at 2:42 PM, Godfrey van der Linden wrote:
Have you ever succeeded in talking to your serial device? Before
going into arbitration just try to setup a simple program that sends
an AT<CR> to the device and make sure you are getting an OK? If you
aren't then you have other issues.
BTW did you use O_NONBLOCK as one of the open flags or are you using
the /dev/cu.??? device?
I've been working with the code as presented mostly, which has been do
the open() non-blocking but then clearing that flag.
The summary of my experiments is that if I open the cu.* device I can
write all I like and get responses/echos but never get a RING. If I
open the tty.* device, I can get a RING but if I make any attempt to
write to the file it blocks.
If I leave it in non-blocking mode, the write() to tty.* gives back
EAGAIN.
Godfrey
On Apr 7, , at 18:21, Gregory Weston wrote:
Godfrey van der Linden wrote:
// At this point you have the port exclusively and non-preemtibly
// so now is a good time to program up the modem or do any other
// equipment initialisation you desire.
Not to be terribly dense, but how? If I try to send an initialization
string via write() I block forever.
Adding O_RDWR to the open() flags had no impact.
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