pic: Team 356 C-Box

[Andrew]

Originally Posted by steven114

Watch out - the 9 pin serial cables (at least the one in last year's kit) are connected from one end to the other, and the sheaths on the robot controller (again at least last year's one) are grounded. You might therefore ground your entire robot body and spend hours trying to track down where it is connected to the battery, with a FIRST official peering over your shoulder... (we sure did )

Thanks for the tip. I definitely plan to verify.

However, the metal sheath on our box-side DB9 is not connected electrically to any of the pins. Therefore, when it contacts the metal of the controller box and thence to the metal robot frame, it is electrically isolated.

The metal sheath on the RC side of the cable is also electrically isolated from the box.

Even if the RC DB9's are grounded to the power ground on the RC box, neither this ground (which is a straight shot through a 20 Amp fuse to the negative of the battery) nor the RC sheathes are connected to the frame.

Which is another argument in favor of a custom controller box. You can control your grounding scheme.