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General Mach Discussion / Re: Hooking up limits!
« on: January 31, 2008, 09:14:04 AM »Quote
The limits im using are Normally open and normally closed with a ground.
How are your limits wired normally open AND normally closed?
It is best to have limit switches wired normally closed. This way when the switch is 'not pressed' you will have a complete electrical circuit. If you feed your switches with common (ground) then in this normal, 'not pressed' state, would provide a 'low' input to the computer. When the switch 'is pressed' the circuit will be open, there will be no electrical connection, and the input pin on your computer will go 'high' signifying the switch has been pressed. Wired this way your limit switch inputs on the computer will need to be set to active high.
The reason for wiring your switches normally closed is that it provides a basic level of supervision of the circuit. If a wire is cut or pulled loose the circuit will be open, just like it the limit was pressed, and your machine will stop before any harm is done.