Wiring home and limit switches

[irving2008]

The reason is that the inputs to the board have to be switched between 0v and +5v. generally the inputs are pulled up to +5v by a resistor on the board and the switches then short the input to ground. An alternative approach is to use both poles of the switch to switch the input line between a 0v wire and a +5v wire. This is how the home switches in the first diagram are wired, as individual inputs. But the same approach is used for the limit switches in the lower part of the diagram and this is just wrong... in fact the way that is wired when one limit switch is activated it puts a short from 0v to +5v, which will probably have the effect of stopping everything but for the wrong reasons.... I would ignore that and go for the single chain of switches. However I would seperate the PANIC switch from the limit switches. A panic switch should always control a relay which supplies power to the motors. That relay MAY have a contact that does the panic input to the breakout board and thence to MACH3 as per these diagrams... one should NEVER rely on MACH3 to stop the motors in an emergency, the panic switch should always act directly...