[jee7s]

Originally Posted by Matt Krass

The black motor terminal of the Jaguar is not a valid common node, it can be connected to both the positive or negative or neither depending on what the Jaguar is doing and how it is configured.

The black power input to the Jaguar (directly across) should be acceptable to use though, at least as far as multimeter probes go.

I don't have one in front of me right now, but I seem to recall that the inputs to a Jaguar use red and black screws and the outputs are colored green and white. The "black" terminal I was referring to was the input side of the Jaguar.

And, Al's right, there's no "ground" in the most literal sense on the robot. My use of "ground" could have probably been better worded as the EE colloquial "virtual ground" (i.e. the node of the circuit from which voltage is measured) or as "common". The chassis being electrically isolated (therefore there is no ground) is an important and sometimes overlooked detail in the FRC.