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Old 12-12-2011, 12:32 AM   #1
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Unhappy Serial: Write timeout for write operation in Linux

Hi all,

I am writing an application to send/receive a bulk data from serial port.
I am able to receive the data that I mentioned in chunks of a page, i.e., 4KB, for each read call.
Like wise, as I know it is only possible to write a page of data at a time.
But in my case I can able to write only 1KB at a time.
Even if I write some data <=1KB immediate after writing 1KB of data I am getting error "Resource temporarily unavailable".
From this I come to know that the delay between two subsequent write operations is not sufficient.
So I kept 100ms delay for each write operation. Then I can able to send as much of data I want.
But it is not a good way of keeping delay.
Is there any other way of keeping timeout for serial write as VMIN and VTIME for serial read .

Thanks in advance.

Old 12-13-2011, 12:08 PM   #2
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Is it possible that your host and/or the peer host have enabled flow control, and that the flow control stops the data for long enough that the write() times out? This would be consistent with the use of delays to throttle transmission of data. If the peer host cannot accept data at any faster rate, then timing out on writes makes sense. At some level, you have to respect the limiting factor, and not simply cache writes ad infinitum.

--- rod.


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