I'm trying to connect a flowmeter to my arduino board in order to get a pressure reading.
I know I need to connect the analog output to A0-5 on the board, but should iI connect the ground to arduino GND?
The flow meter is powered externally.
I'm possibly being overly cautious, but I've fried so many components that I'd rather be certain.
The meter is TSI 4000 series.
Output according to the datasheet is 0-10V DC, so you'll need a voltage divider. 9:1 is a good ratio, bring down the voltage to about 1V, read against the internal 1.1V reference. This appears to be an absolute output so you need an absolute reference, the sensor takes 7.5V as input and up to 10V output which means there must be some voltage boost circuit in there.
You might find Common ground and why you need one useful.