Dc/dc isolated converter proper grounding

Other Hardware General Electronics
1

Hi,

I have 24VDC power supply. I use it to power external sensor and Arduino Mega 2560 through dc/dc isolated converter TracoPower TEL-8-4811 to 5V. The output from sensor is 0-20mA signal which I convert using resistor to 0-5V. However, I do not know how properly connect the ground signal. I think I cannot use the common GND for all because the dc/dc isolated converter wont be isolated any more. Any suggestions? Thanks.

2

You must use the 0V output of the DC-DC converter as the local, isolated ground for the Arduino and associated circuitry.

You can think of the converter as a 5V battery. The negative "battery" terminal is ground.

3

That only matters if you require that isolation - if you don't need the isolation you can common grounds between input and output sides of the converter (though in that case a cheaper non-isolated converter would have been sufficient). Isolation is a feature provided by the converter, not a requirement of it. Isolated converters need internal transformer(s), raising the cost.

4

Thanks for confirmation.