[lonnie lascelle]

We have noticed back EMF noise generated from the motors to cause false tripping "limit switch closures" on our robots. Many of the false triggers can last for a second or two. Filtering in code, suppressing via capacitor, using 5 volts as input, using ferrite doughnuts, and assuring good wiring practice(keeping wires as short as possible for motor and signals, twisting pairs, not running signal wires near or in parallel with motor power wires). generally eliminates these issues. Be sure to ward off this in all areas to limit the issue. Have you tried to put a meter on the limit switch? Start by using a AA battery in-line and set meeter to hold peak or min/max hold (assure the robot wires are not connect) and then drive the robot causing vibration to see if it actually mechanically opens or bounces? Try to confirm that the limit is mechanically vibrating open and closed. We have often thought that we must have a bad limit or excessive vibration only to find noise.