Herbert,

I have used Win2K / XP with multiple USB serial devices, and can report =
2
big problems:

1/ The COM ports frequently re-enumerate (especially when
plugged/unplugged), and as a result the COM port numbering sequence can
change.

2/ Many of the USB COM port drivers don't work reliably with more that 2
adaptors present. I have however, used a device from 'Keyspan' that =
reliably
supports 4 USB com ports.

Can I suggest RS485?

Peter Moreton


> -----Original Message-----
> From: pic microcontroller discussion list=20
> [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Herbert Graf
> Sent: 22 June 2004 18:51
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: serial port dilemma - design advise requested
>=20
>=20
> On Tue, 2004-06-22 at 11:44, Trungie*! wrote:
> > I have a PIC device that connects to my PC via serial port=20
> for constant
> > communication.
> >
> > I would like to have over 10 PIC devices connected to my PC=20
> somehow for
> > communication.
> >
> > However, i would not like to buy some sort of expensive=20
> multi serial port
> > card for it.
> >
> > What sorts of things can i do to over come this problem?=20
> Potentially i would
> > like to use over 10 of these PIC devices at once.
>=20
>         What about USB? Either by converting your devices to=20
> USB or using
> USB-serial ready made convertors. I think the limit on ONE USB port is
> 127 devices, FAR more then the software limitations you'll=20
> hit first! :)
> TTYL
>=20
> -----------------------------
> Herbert's PIC Stuff:
> http://repatch.dyndns.org:8383/pic_stuff/
>=20
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>=20

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