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Re: [ts-7000] ttyS0 linux serial buffer size

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Subject: Re: [ts-7000] ttyS0 linux serial buffer size
From: Jim Jackson <>
Date: Tue, 19 Dec 2006 21:45:12 +0000 (GMT)


On Tue, 19 Dec 2006, kendwyer wrote:

> Hi,
>
> I am using the TS-7260 system for my application. I have found that
> the tty (at least ttyS0) will only read 4096 bytes as a defualt
> maximum, when my user code executes the following, r =
> read(ft,ser_databuf,4096);.
>
> When I change the code as follows:
>
> res1 = read(ft,ser_databuf,8192);
>
> I still only read 4096 bytes...
>
> How/where do I change the code to read greater than 4096?
>

Read the man page for the read function

  man 2 read

on most any linux desktop.

I quote......

       On success, the number of bytes  read  is  returned  (zero
       indicates  end of file), and the file position is advanced
       by this number.  It is not an  error  if  this  number  is
       smaller  than the number of bytes requested; this may hap­
       pen for example because fewer bytes are actually available
       right  now (maybe because we were close to end-of-file, or
       because we are reading from a pipe, or from  a  terminal),
       or  because read() was interrupted by a signal.

re-code your application to loop on the read call until you've read all
the bytes.



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