Common Ground on Limit Switches

[Gary Bonner]

We have 4 limit switches on our arm and it would be great if we could run only one ground wire out there. Is there any problem connecting all for to the same ground pin on the RC? Could we add a couple of optical encoders to the ground also?

Thanks.

[Alan Anderson]

All the grounds of the digital in/out pins on the RC are common. As long as you don't have too much current flowing, or run the wires too closely in parallel with motor leads, you'll probably be fine running a single ground to all your switches.

[phillutz]

We are currently connecting 11 digital using 1 ground pin.
Works fine.

You can actually glue (c/a) the connector together and save pwm cables in the process.

Here is an ascii pictorial of our arrangement. only 4 cables were used instead of 11.

o|ooo|ooo|ooo|o <- sig
o             o
o             o <- ground
-                -

Hope this helps.

Phil

[eugenebrooks]

We routinely use a common ground wire for switches, but we prefer to use several "pins" for the connection. That way, if the "one and only" ground pin connection goes bad, you don't lose all of your digital input functionality.

[Al Skierkiewicz]

Originally Posted by eugenebrooks

We routinely use a common ground wire for switches, but we prefer to use several "pins" for the connection. That way, if the "one and only" ground pin connection goes bad, you don't lose all of your digital input functionality.

Ageed,
With sensors being so important to your software feedback and control, this is not a place to skimp. No single point failures keep you playing.