Recently, Somebody Somewhere wrote these words
> Hi,
>
> Thanks.
>
> I think I should have been more specific.
>
> We've got an RS485 comms pair, which we want to multiplex between 120
> RS485 pairs.
>
> I.e. 120 channels to 1 (or 240 to 2 in terms of actual wires).
>
> Ive seen a 32 channel analogue switch from Analogue devices, but im
> unsure as to whether an Analogue switch will be ok?
>
To quote the Irishman who was asked for directions to somewhere:
"You know... If I was you, I wouldn't start from here at all!"
You are never going to stand up 1-->120 in an RS485 link without such
heartache as to justify a sane design. What's your baud rate? You would
also need sample & holds everywhere. Network the things and address
them. Start over, my friend.
Imagine when you get the complaint "Channel 87 goes intermittent after
about 5 minutes" How will you sort that?
BTW, the trick with analogue switches is never bring the input below the
negative rail.
--
With best Regards,
Declan Moriarty.
--
Author: Declan Moriarty
INET: [EMAIL PROTECTED]
Fat City Hosting, San Diego, California -- http://www.fatcity.com
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