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[ts-7000] Re: Serial port COM2 blocking/nonblocking

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Subject: [ts-7000] Re: Serial port COM2 blocking/nonblocking
From: "tommessum" <>
Date: Wed, 19 Jan 2011 15:11:09 -0000
BTDT! 

My bet is that things will start to happen if you read one character at a time  
e.g.  read(fd,buffer,1)  



--- In  "Mike Jubes" <> wrote:
>
> 
> Considering the recent posts on COM2 processing, I am having an odd problem 
> when setting VIM and VTIME on the tc attributes structure. 
> 
> I find that on a read() I can get the call to block, or not block at all. But 
> I can't get it to time out.
> 
> e.g.
> 
> If I set: 
>         newtio.c_cc[VMIN]  = N;
>         newtio.c_cc[VTIME] = 0;
> Read will block until N characters are received, this is as expected. 
> 
> However, if I set: 
>         newtio.c_cc[VMIN]  = N;
>         newtio.c_cc[VTIME] = M;
> 
> Read will still block until N characters are received, but the timeout (m/10 
> seconds) never happens (even when at least one characters are received) This 
> is not expected behaviour.
> 
> Similarly, if I set: 
>         newtio.c_cc[VMIN]  = 0;
>         newtio.c_cc[VTIME] = M;
> 
> Read() returns non-blocking with no data (This is not expected behaviour, the 
> call  should block and return after M/10 seconds) 
> 
> Any ideas? 
> 
> 
> Oddly enough, I have tried the above on the console COM1 (STDIN) and it 
> works, i.e. I can get the timeouts on input to work properly! 
> 
> PS I have modified /etc/inittab so that COM2 is not enabled as a console.
>




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