G540 and NPN Prox. Switch

[kolias]

Sorry John, another thing came to my mind. How do I test the sensors?

I connect the brown and blue to my 9VDC battery and where do I connect the black to give the signal to the sensor?

Nicolas

[john-100]

Hi Nicolas

if you can see the LED built into the proximity switch
just connect the battery to the Blue & Brown wires and insulate the Black wire to avoid contact with the positive supply

for a remote indicator how about this for a simple tester -



you can use either a LED plus 2200 ohm resistor
or
a ready made "12V LED" with its built in resistor

John

[kolias]

So simple if you know what to do, it worked and thanks John

I don’t have any LED, just connected the sensor to my 9V battery and as my screwdriver approached the sensor the red LED on the sensor lit

Thanks for your time

Nicolas

[kolias]

Hi John

If you have the time and you are familiar with the Chinese VFD would you like to have a look at the last post of this thread? I posted my question last Friday and have no answer

http://www.cnczone.com/forums/genera...er-pump-2.html

Thank you

[john-100]

Hi Nicolas

I don't know why I did not look earlier but iI have a LED Tachometer + Hall Proximity Switch Sensor NPN to add to a lathe

the proximity sensor is this one



a quick test proved the LED indicator is connected to the brown and black wires
(I am sure an other proximity swith I looked at had the LED connected to a second internal output)

my sensor looks like it is a normally closed version of the proximity switches you have

if thats the case ,
with your switches wired in parallel when one switch operates the LED will light on all switches will light
this does not stop them working correctly with the G540

but if thats a problem adding a diode to each black sensor wire will solve the problem



see corrected diagram in post 27

I don't have a VFD but I will have at the other thread

John

[kolias]

Thanks for pointing out this to me John however you are saying to add the diode to black sensor wire but on your schematic the diode is on the brown wire. Which one?

[john-100]

Hi Nicolas

you are correct I made an error late last night

the corrected diagram



this is the same circuit from my post in the DIY Hall switches thread here on cnczone

http://www.cnczone.com/forums/open-s...-forum-46.html



John

[kolias]

That’s excellent John, thanks

Your schematics are always amazing and I love them because I can read them

[kolias]

Another item I forgot John is the wiring. As I mentioned each sensor has approx. 30” of cable attached and as the time comes to install the sensors and do the wiring I’m asking your opinion.

I will use a 4 conductors 20 or 22AWG shielded cable (I know I only need 3 conductors but my store only has 2 or 4 conductors) to extend the existing cable from each sensor.

Should I cut the sensor cable and leave about 4” to solder my new cable or utilize all the existing cable of each sensor and solder my new cable at the end of it?

And if I install the diode, should I enclose it in the heat shrink tube (I don’t know if it will fit inside the heat shrink)

Thanks
Nicolas

[john-100]

Hi Nicolas

I'm glad you find the diagrams readable as I try to keep in mind not all members here are electrical or electronic engineers

the second diagram in post 27 is a mixture of Roman Lini's Diy proximity switch and the diodes I added to connect several switches with a Gecko G540 input

I assume 22 / 24 AWG is about the same as the wire on the proximity switches

at first I would be tempted to test the proximity switches with the cable cut to 6 to 8 inches long
so you have enough wire to remake the joint 2 or 3 times

while you can add the diode at either end of the screened extension to the proximity switches black output wire

I'd add the diode at the control box end of the cable -
solder the marked end of the diode (cathode) to the wire and cover with heatshrink sleeving

I expect you can only insert 3 , possibly 4 diode anode wires into a G540 input terminal - some makes of the 1N4001 diode has thicker wires than others

you may need to use a terminal block to use more proximity switches to one input


John

[kolias]

I didn’t noticed but it’s a good idea, you connect one end of the diode to G540 and the other end (cathode) to my shielded cable, very neat.

Cutting the sensors wire 6-8” long sound good and yes, I intend to use terminal blocks which will make wiring much easier

I have decided on the following unless you see something wrong

X+/X-/X Home/Z+/Z- to Pin 1
Y+/Y-/Y Home to Pin 2
A Home to Pin 3
Probe to Pin 4

Planning to install the sensors (physically) in the next couple of days and since I never used proximity sensors before I anticipate to have problems installing the two I want on the Z axis. Proximity sensors require much more space then micro limit switches and on the Z axis the available space is limited. Hopefully I will manage

[109jb]

Not sure if you know this, but prox switches work almost equally well with the target moving sideways past the sensor (Method #1), compared to the target approaching the sensor head on (Method #2). I have done testing with them both ways and both methods can achieve homing repeatability of about + or - 0.0002" This may help when planning the actual switch installation.



Also, although it doesn't apply specifically to the application presented in this thread (G540 & NPN Prox switches), someone else looking for prox wiring info may need to know the following:

When using a prox switch such as these you need to be aware of the tolerance of the pins you are connecting to. For example, here methods have been shown for connecting a 12V prox switch to a G540 that has pins that are apparently 12V tolerant. Some BOBs or controllers are not so tolerant. For example, I use an Arduino Uno running GRBL for my controller and the limit pins on the Arduino Uno are only 5V tolerant. Likewise some people use Ardino DUEs which are only 3.3V tolerant. Wiring a 12V prox switch directly to them would kill the Arduino. Some BOBs are the same way. The easiest method I have found to combat this is to use a miniature 12VDC relay using the prox switches to activate the relay coil, and then using the NO or NC contacts to connect/activate the pin either to ground, or to the Arduino/board/BOB VCC pin. Essentially connecting the relay the same way a mechanical switch would be connected.

[john-100]

Hi Nicolas

I don't see any reason why you can not use the inputs as planned

X+/X-/X Home/Z+/Z- to Pin 1
Y+/Y-/Y Home to Pin 2
A Home to Pin 3
Probe to Pin 4

Hi 109jb

good point about the Arduino inputs
like PC parallel printer ports the Arduino I/O pins need to be protected by a buffered 12V tolerant breakout board / shield

powered by a 12V supply , proximity switches with NPN open collector outputs are OK
provided they don't have any pull up resistors or LED indicators between the +12V supply and the output

the information has now become hidden in Roman Lini's thread I linked to

John

[kolias]

Thanks for taking the time to let me know 109jb

Since this is the first time I will use prox switches I learn as I go along and your method #1 definitely will help a lot. Last night I was looking how / where to mount them I knew it will not be easy but method #1 will help a lot.

Much appreciated

[109jb]

good point about the Arduino inputs
like PC parallel printer ports the Arduino I/O pins need to be protected by a buffered 12V tolerant breakout board / shield

powered by a 12V supply , proximity switches with NPN open collector outputs are OK
provided they don't have any pull up resistors or LED indicators between the +12V supply and the output

I don't disagree with this, but I think you will be hard pressed to find a prox that doesn't have an LED or a pull-up or both.

[john-100]

Hi 109jb

I guess its all down to your suppliers in your part of the world

a quick search of ebay finds switches with built in LED indicators
but industrial suppliers like RS components you can also find switches without LEDs or pull up resistors

[109jb]

Yep. I was just considering the most likely prox switches to be used by DIYers.

[kolias]

Hi John

I was looking at a YouTube video and this guy had a prox. sensor which included an adjusting screw next to the sensors LED light. Mine does not have an adjusting screw and after installing my first sensor the light comes ON when my Gantry is less than 1/8” away which is too close for comfort.

Is there a way to make my sensors adjustable?

[john-100]

Hi Nicolas

can you post a link to the video to see what he is doing

please post a photo of you machine and showing how you have mounted the magnet and proximity switch

it should be possible to mount any limit switch to stop the machine with a reasonable amount space still left before you are in danger of crashing

John

[kolias]

Hi John

Here is the link to the video


And a picture of my first installed switch although I still not sure if that’s the final way to install the rest, just experimenting right now