Controls

4-20mA to 2-10V resistor, 4-20mA BMS input, 500 ohm resistor 4-20mA, convert current signal to voltage HVAC

If a field sensor outputs 4–20mA but the BMS controller only has a voltage input, can you convert it using a resistor?

Yes, provided the transmitter and input arrangement are suitable.

Using Ohm's law:

V = I × R

With a 500Ω resistor:

4mA × 500Ω = 2V

20mA × 500Ω = 10V

So 4–20mA becomes 2–10V.

A 250Ω resistor gives 1–5V.

The resistor is normally used as a shunt/load across the voltage input—not simply added randomly in series.

Also check the current transmitter's permitted loop load and power supply before doing it.

This is one of those simple controls tricks that's worth remembering.