--- In uhmgawa <> wrote:
>
> Jesse Off wrote:
> >
> >
> > Yes, but those cables are very unique and typically very
expensive.
> > Since DB9's are by far the most common connector for serial
ports,
> > the board would be useless without including that cable which
would
> > add cost to everybody's end product. I don't know how much the
cable
> > below costs, but somebody else's octopus cable costed $88 when we
> > looked at it!
>
> Unless I miss something here you'd still need to create custom
> cables to break out potentially three async ports contained in your
> custom DB9 pinout to multiple standard DB9 serial ports.
Yes, but only if you want to. By default, each DB9 is 1 serial port
with full handshaking lines. Only once you've used 9 do you start
to have to worry about custom cabling. Once you use 25, you have to
worry about a custom enclosure. Once you use 34, you have to worry
about having to add PC/104 cards as well as a custom enclosure.
We have used RJ45/RJ11 for serial ports in the past. But they
aren't quite as ubiquitous as the DB9 and the price diff between a
DB9 and a RJ11 doesn't amount to much when you average out that most
people will probably be connecting the RJ11 into a DB9 anyway and
needing the adapter.
In any case, this product was specified by somebody else and we
built to their requirements. The serial ports come off the board
as .1" headers internally -- it would be trivial to do another
enclosure with all 34 serial ports as RJ11's or octopus cables if a
customer wanted it.
>
> Other potential solutions which seem more OTS (read: cheap) would
> be multiple RJ11 connectors, one for each async port. These are
> about the cheapest external connector available and RJ11 to DB9
> adapters do exist though most commonly as tool-free u-wire-it kits.
>
> RJ45 connectors are perhaps a second choice from a OTS perspective
> and while a bit of overkill in terms of pin count they are
> available in banked/stacked modules which would offset the added
> footprint multiple discrete units would bring into play. RJ45 to
> DB9 adapters are even more ubiquitous.
>
> Probably hands down the cheapest solution is the ancient PC 2x5 10
> pin async header. Though bringing these out externally has
mechanical
> issues the "as shipped" cost should be fairly low and the header to
> DP9 adapter cables are common.
We aren't as concerned as much with the "as shipped" cost as we are
with the customer total system cost including often "hidden" costs
such as cabling and assembly. If we were into just the having of a
board with the least possible cost, we'd just be manufacturing SIMM
style card-edge boards with a CPU + RAM chip-- which is a bit
extreme IMHO.
//Jesse Off
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