Autosport Labs

In looking at the wiring diagram for the RCP I am noticing there is no dedicated signal ground. Further, any references to sensor ground seems to indicate that things should be tied to the "same ground point" as the RCP.

* What is the difference between the 12v power - and the "GND" on the CAN RJ45? CAN signals are not GND referenced.

* What is the purpose of the 12v power on the CAN in? CAN is not BAT referenced.

* How are people isolating chassis ground noise / ground float for sensitive signal measurements? Or is the RCP producing a 5v reference that is in relation to the floating chassis ground?

As an example, consider a 10kOhm 10-turn potentiometer used to measure steering angle. With a 5v reference signal at dead center on the pot, normally you would be at 5kOhm and 2.5v of output against true signal zero. However, if chassis ground floats even a little, it would look like the steering wheel is being moved a great deal.

There's only one ground reference. What we recommend is that you simply route dedicated ground and vref signals to the same ground point that RCP use (google "star grounding technqiue") Don't rely on the chassis for sensor ground. Your results should work well.

The CAN connector has duplicated 12v and ground connections so the entire unit can be conveniently powered by the CAN OBDII cable. The ground and 12v are internally connected to the respective GND and 12v on the terminal block.