I have a sensor device that puts out 0 to about 4V. The device uses its own powersupply. How do I connect it to the analog inputs? Can I just connect the + cable to the signal pin and the - cable to the ground pin?
Consult the data sheet on your sensor to be sure. You are correct if the output signal is the + cable and the sensor ground is the – cable. If you can measure the output to ground(+ cable to -cable) with a volt meter and can see it change from 0-4 volts, you should be able to see this change on an Analog Input.