Serial Port Expansion Card for Linux?

Levi Pearson levipearson at
Tue Jan 12 22:14:12 MST 2010

Charles Curley <charlescurley at> writes:

> On Tue, 12 Jan 2010 19:16:26 -0700
> Kenneth Burgener <kenneth at> wrote:
>> Hi,
>> Has anyone successfully used a serial port expansion card with Linux 
>> (specifically Red Hat)?  What brand and model did you use?
>> I was thinking something like this would work great, if it would be 
>> correctly recognized by Linux:
>>   SIIG Four 16650 serial port I/O card with 4-port (DB9)
> Linux should recognize that, as the AT hardware specified up to four
> 16650s. But I can't say from actual experience or reading the source.
> Something else to watch for: the actual 16650 had, if I recall
> correctly, an eight byte fifo for each direction. Later versions have
> larger fifos. The larger the fifo, the longer the chip can go between
> interrupts without loosing data. I don't know if your application will
> require the larger fifos, but it's something to keep in mind.

I actually did the embedded software for a device that included a serial
concentrator, and it ran Linux.  At the time, I had to hack the serial
driver to get it to use all of the 16650s available on our board, but I
think that later kernels may have made the hack unnecessary.  I'm afraid
I don't remember for sure, as it's been a long time.

But anyway, as long as the card presents itself as a bunch of 16650s,
you should be able to make it work with Linux with some amount of
work, hopefully not including hacking the serial driver. :)


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