> > But I want to avoid needing a power source at the 4-20mA side.
>
> So what's supplying the current to the sensor, then?

Some source that I would like to avoid connecting to (two wire interface
instead of three wire).

Unless I find an easy and cheap way to couple without using power I will
probably go for using power at the 4-20mA that, and in that case it
makes sense to do the A/D at the 4-20mA side and use a simple
optocoupler to go to the RS-232 side (probably stealing power from the
handshakes at the 232 side).

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products

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