Spider and custom sensors

My electronic skills are close to zero, so this might be dumb question. Anyway, how can I connect / measure, sensor with fez spider that has defined measured range from 4 to 20mA. It has own power supply. On fez we need information about voltage. I don’t have information about resistance, so that I could use ohms law.

Similar question is for sensors that have defined measurement range in resistance.

Thanks for tips

Use an Expander Module from GHI and wire it to a socket that supports Analog In (A socket).

Yes, i try to measure current. What is the role of shunt resistor?

Thanks for description, this is what I needed. So basically if I wan’t to:

  1. Measure voltage - no problem, measure voltage
  2. Measure Current - use shunt resistor, and measure voltage drop
  3. Measure Resistance - ?

Thanks. It’s very helpful information for beginners.