Re: Demise of the COM port?

From: Viktor Kesler (viktor_at_cardware.co.yu)
Date: 03/19/04 

Date: 19 Mar 2004 14:13:28 -0800

rickman <spamgoeshere4@yahoo.com> wrote in message news:<405A4DA3.3260FD95@yahoo.com>...

> For example, the give away Cypress PSOC invention board uses USB. One
> chip, likely cheaper than an RS-232 converter, provides the USB
> interface. The connectors come in two flavors, small and tiny. It was
> designed from the get-go (not gecko) to be low cost and yet run at 12
> Mbps at 5 meters. I like it and I will be getting very used to it.
>

Yes, but we need 9600Bd at up to 1km with a few kV isolation.
We use a 20mA-loop dongle stuck into the PC COM port. Works like a
charm and the only thing that can burn it is a lightning strike - and
even then the PC never gets damaged, only the dongle.

So, building USB into our product doesn't make sense because it's not
near the PC. We've already got an ethernet tcp/ip module, but that's
not much use if there isn't already a LAN running around the place.

Using USB/RS232 converters seems to be the only option, but the few
types we tested cause delays so we had to tweak our PC software to get
them to work.

The question is, will all USB/RS232 converters behave in the same way?
I'm thinking of delays and out-of-the-ordinary stuff, like changing
the parity on-the-fly between two sent characters etc.

Viktor

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