Recognizing external ground on analog input

[vamin25]

Hello there,

I was wondering how I can get an arduino analog to recognize a ground from another power source without making a common ground. Is there an IC or some other method I could use to control this?

[DrDiettrich]

Every reliable wire bound communication requires 2 wires.

Digital signals can be isolated by optocouplers, analog signals don't work well this way.

[SteveMann]

In general, all grounds should be common. There are very few exceptions to this. Why do you have separate grounds?

[DVDdoug]

Is there an IC or some other method I could use to control this?

And optical isolator can have isolated grounds on each side.

For AC signals a transformer can provide isolation and for "slow switching" a relay can provide isolation.

[hammy]

You can get isolating voltage transmitters - they are not a simple IC tho. Your project may give us a clue as to why you need to do this

Example

[Paul_B]

@vamin25

I was wondering how I can get an arduino analog to recognize a ground from another power source without making a common ground.

Sorry, that does not make much sense. Have another try at explaining your actual requirement.