Recommendations for a serial port card you can actually BUY?

Bob Johnson fbsdlists at gmail.com
Thu Oct 5 21:04:45 UTC 2006


On 10/5/06, Karl Denninger <karl at denninger.net> wrote:
[...]
> > > I know serial I/O is passe for many, but some of us have applications
> that
> > > actually require it, and can't rationally be moved to anything else due
> > > to external hardware considerations.
> >
[...]
> Serial over IP will not work for either.  Serial-via-USB might, and I will
> look into that, but I suspect I'm going to get in trouble with that one,
> especially if I have to toggle control signals (e.g. DTR, etc) or support
> hardware flow control (and for the fax servers, you DO need it if you expect
> things to work correctly.)

I have used USB-to-serial converters with no problem. All the control
signals (at least the ones my applications need) seem to work
correctly. I don't remember any brands or models off hand, I bought
what was cheap as I needed them and they all worked. "Cheap" means
under $20 delivered (for one port).

>
> FreeBSD's USB support has always been somewhat deficient.  For example,
> apcupsd can't talk to their UPSs over the USB bus, even though the software
> itself knows how, because FreeBSD doesn't know what a UPS is and throws up
> its hands when you plug it in.  I wasn't aware that the USB to Serial
> converters would work - I can try them, but there are a lot of those out
> there that don't work right even under Windows - expecting them to under
> FreeBSD might be asking too much.

I've had no problem getting them to work in FreeBSD. I've had some
trouble getting them to work in WIndows. YMMV, but they are so dirt
cheap that the time it takes to test one will likely be more
significant than the cost of the device.  "man uplcom" will give you
an idea of what chipsets to look for, although determining the chipset
in one of those things is frequently impossible. The uvscom driver
seems to support another chipset, but none of my devices use it so I
don't know how well it works.

At the moment I can't tell you what version of FreeBSD I'm using these
under, probably 5.3, maybe 6.0.  It isn't reachable to me from where I
am.

- Bob


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