[LCP]reg serial communication in linux.

[Andrew Weaver]

On Wednesday, October 15, 2003 8:28 AM, sowmya.k [SMTP:sowmi99 at yahoo.com]
wrote:
>  I could execute my program well but It just hangs while reading data. 
>  I tested whether my data is transmitted or not through
>  
>  cat /proc/tty/driver/serial
> It says  that
> 0 :uart:16550A port:3F8 irq:4 tx:3 rx:0 (becoz I am making use of ttyS0)
>  
> where has at the receiver end I got the message as
>  
> 0 :uart:16550A port:3F8 irq:3 tx:0 rx:0
>  
> Are there any formatted way I should follow such that the written data can
be properly read.
>  
> Thanx i advance
> Sowmya

Have you checked the pin connections on your cable? You say you have null
modem and that (IIRC) will deal with RTS/CTS. Have you checked that the RX
and TX pins are crossed? Are you aware of DCE vs DTE? 

I think they are pins 2 and 3 but it's been a while. Nub of the point is
that if 2 is the send on one side, then 3 is the receive on the other (or
vice-versa obviously).

 
> Andrew Weaver <Andrew.Weaver at tecnomen.fi> wrote:
> 
> 
> 
> On Tuesday, October 14, 2003 12:19 PM, sowmya.k [SMTP:sowmi99 at yahoo.com]
> wrote:
> > I had connected 2 systems using null modem
> > cable(RS232). 
> > My problem comes in the reading part.
> > My coding goes this way.
> > First I had opened my tty (i.e my terminal screen
> > and keyboard)
> > Then I set some parameters to it.
> > Third I opened my port and finished all my
> > settings.
> > Fourth I started to write and read datas from the
> > port.
> > Atlast I closed everything.
> > Let me give the code I used to read and write
> > 
> > 
> > To write datas to the port
> > 
> > while (STOP==FALSE) //STOP is defined to be
> > TRUE
> > {
> > status = fread(&Key,1,1,input);
> > if (status==1) //if a key was hit
> > {
> > fputc((int) Key,output);
> > write(fd,&Key! ,1); //write 1 byte
> > to the port
> > } 
> > }
> > 
> > 
> > 
> > To read from the port
> > 
> > if (wait_flag==FALSE) //if input is
> > available
> > {
> > res = read(fd,buf,255);
> > if (res)
> > {
> > for (i=0; i
> > in string
> > {
> > In1 = buf[i];
> > printf(message,"%c ",In1);
> > fputs(message,output);
> > }
> > }
> > wait_flag = TRUE; /* wait for new
> > input */
> > } //end if wait flag == FALSE
> > 
> > } //while stop==FALSE
> > 
> > 
> > Thanking you
> > 
> > sowmya
> > 
> So... what is the problem that you are getting?
> 
> 
> 
> 
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