what is the common practice for limit switches on a cnc machine using arduino+cnc shield
NO ot NC as my software cant detect them when they are connected
I have them wired up as Normally open (NO) and software is the openbuilds control
and input would be welcomed
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Most are N.O.
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If the wire breaks, however, there is no error detection
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N.C. on the other hand can detect an open wire, however, not a shorted wire.
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A N.O. with a parallel 1k resistor (for supervision) (or N.C. with series 1k) is a good option; an analog input would be used . . .
Common practice is no limit switches. Use a switch to indicate the ZERO position of each axis. The CNC code should know what the limit is for each axis in number of steps from zero.
- Limit switches can be dual function, the Start switch and the Crash switch.
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Limit switches have contacts which will corrode in time. Unless rated for dry switching they need some current so they will clean themselves. I use a minimum of 1 mA through the contact prefer more if possible. Switch configuration was determined by the actual application.
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