Which ground pins to use for an analog input from other device.

Dear all,

I want to use arduino to get the output of three devices which output the temperature 0-50C as voltage 0-5V.

I connect three cables with BNC connector to each of the output port of the three machine, and then connect the other end--3 positive line and 3 negative line to the pins on arduino uno board.

The positive pins is to connect among A0-A5.

Which pin should I use for the 3 negative line? The ground pins near power, GND on other side, or the AREF?

Thanks.

The gnd pins.

hammy:
The gnd pins.

Thanks.

I also use this arduino uno to do 8 digital TTL output to another device, and also use 1 PWM pin to do analog output(0~5V) to another device. Is it OK that I connect all these ground lines and into the GND pin?

Is it OK that I connect all these ground lines and into the GND pin?

Yes.

rmd06:
I also use this arduino uno to do 8 digital TTL output to another device, and also use 1 PWM pin to do analog output(0~5V) to another device. Is it OK that I connect all these ground lines and into the GND pin?

In most situations that's not just OK, it's a requirement to make everything work (connecting GND completes circuits and provides a shared reference point).