Measuring 4-20mA current loop without common ground.

[haxan7]

I am powering my microcontroller and a device that outputs 4-20mA current from the same power supply, so I need a circuit or an IC that can measure 4-20mA loop without a common ground, because they will already have a common ground.

 

[crutschow]

Add a small resistor in series with the loop and measure the voltage across the resistor with a Difference Amp or an Instrumentation (differential) Amp.

 

[ahsan_i_h]

I am powering my microcontroller and a device that outputs 4-20mA current from the same power supply, so I need a circuit or an IC that can measure 4-20mA loop without a common ground, because they will already have a common ground.

I do not see any problem with common ground. The current signal is only dependent on measured quantity and does not get affected by ground loops.