Quote:
Originally Posted by Al Skierkiewicz
Eric,
Although electrically that would seem to work, you would need to follow other electrical system rules for combining wires, insulating same and connecting to the DSC. The wiring convention provided is designed for you to be able to use commonly available PWM cables for interconnect. In general digital inputs will come from different locations on the robot, it would seem that a common point for digital inputs is contrary to good practice. Additionally, using the intended interconnect method will give slightly better noise immunity by providing a separate path for noise on each cable directly to the DSC rather than comprimising all digital inputs with a common ground outside of the DSC. Finally, and more importantly, a common point outside of the DSC gives a single point failure for all digital inputs if the wire breaks or becomes disconnected.
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We will be creating a a few sensor bus lines that combine sensor wires from key areas of our robot, and therefore will only be using the PWM MOLEX connector for connection from the bus breakout to the DSC. Using a common ground (at least one common ground per bus) would greatly reduce the complexity of our bus system. At most, we would be connecting 4 components (encoders) to one ground and 3 components (encoder + limit switches) to another ground. Would the added vulnerability to noise in this system be non-negligible for digital signals?