Thread: Limits, homes, override switch
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22-02-2016 #5
Hi,
First - What switches are you using for homes and limits ?
The 3 wire Inductive type of switch usually floats (no connection) or grounds the switch contact depending on whether NC (normally closed) or NO (normally open), The fact that you use 24v or 10v to power the inductive sensor doesn't matter.
NC are normally wired in series with the first switch being connected to actual GND and the next switch getting its GND from the preceding switch NC contact, with the last switch in the series having the NC contact going to the BoB. This means that if any one switch is triggered then the input to the BoB goes to 'float' and circuitry inside the BoB lifts it to logic 1 (active high).
NO are wired in parallel, so that if any one switch is triggered, the input to the BoB is forced to GND (logic 0, active low).
As Jazz says relays are unnecessary and cause errors in Homing precision.
NC switches are preferred as they fail to 'safe' if you have a circuit break.
Cheers,
Rob
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