CNC Limit Switches - Lever, IR and Hall Effect

In this video I go over three different types of limit switches that can be used on a CNC to provide protection from the CNC hitting hard limits.

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[IHHAY]

I find dozens of wiring diagrams for connection to an ardino but none for connecting to a mach 3 BOB, is that they cannot act like a Normally Closed switch, or they just don’t work on my type system. I really need a wiring diagram for my system.
Thanks.

[bulldogg]

Did you use his rj-11 breakout board or did you wire it directly to your own BOB?
i have purchased a set but his BOB is on backorder since feb. The wires are really small

[gracewoodworks]

Thanks for this, I have lever switches the same as yours on my CNC- I am looking for a better way of doing it though as I need to use them as homing switches to get an accurate zero point that the machine can return to. I hadn't heard of Hall switches before. I use Mach3, can I do a straight swap from limit to Hall switches? I guess it depends on the voltage rating of the Hall switches?

[ronald]

I noticed in the video you stated that when the South Pole of the Magnet came near the Creltek Sensor the Voltage would Drop. In the accompanying PDF file that Kevin Patterson provides with his setup, he States that it should be the North Pole of the Magnet. Also are your Creltek Sensors setup as Normally Open or Normally Closed in Mach3? Anything you can offer in information would be greatly appreciated.

[isettech]

Personally I prefer the inductive proximity switches. They don't collect metal shavings and they don't need magnets. They are available in NC and NO configurations as well as open collector (pull to ground) or PNP (pull up to supply). NO open collector devices can be wired in parallel so a home can function as a near limit and it's compliment can be the far limit on an axis. They are generally sealed and immune to coolant mist, metal shavings, etc. As a bonus, most are quite inexpensive. Most work from 12 to 24 volts. The open collector ones just ground the output so it is comparable with 3.3 or 5V logic inputs. They have a positive acting hysteresis curve like a snap switch.

[JaymeVanAuken]

Update His video : This video isn't available anymore

[jazekerxx]

a hall effect sensor is also an analog device. yours has an comparator (opamp) attached wich compares the analog value to a set value of a potmeter(variable resistor) or resistor. if it's below the threshold the output is off and above it's on.
so with this comparator (opamp) you can make any analog device a digital one and set the threshold(on/off point) with a potmeter. very easy! the LM358 is often used for this.
for your other issue, the normally open device like the IR sensor. you can invert the output with just one NPN transistor. also very easy. example BC337

here some examples:
Comparator:
R1 and R2 combined is the potmeter, Vin is the analog input and Vout is the digital output.
both examples for normally open/closed called inverting and non inverting.

LM358 has 2 opamps just use one.

transistor inverter: