>> I've got a situation where I need to sense maybe 24 contact closures to
>> "ground" and drive about 24 open drain outputs. The sense and drive
>> circuitry needs to be on an isolated supply to avoid a ground loop with
>> the equipment that is driving it (referenced to its ground). It seems
>> like
>> the simplest way to get data back and forth is to use a UART in a PIC on
>> the floating side and two opto-couplers, one in each direction to talk
>> to
>> a UART on the nonfloating side.
>>
>> Any ideas for something simpler?
>
> I don't get the full picture. Is there one "ground" to which the
> switches close, or one per switch? Idem for the OC outputs?
>
> --
>
> Wouter van Ooijen


Sorry if I was not clear. There is one "ground" to which all switches
close, but it is not the ground I'm standing on (it may be a hundred or
more meters away) and on a different AC circuit. Ideally chassis would all
be at the same voltage. Unless they are in the same equipment rack, they
generally are not.

Harold




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