[kolias]

I have used lever type micro limit / home switches before but for my new cnc I would like to try proximity switches which I never used and don’t know anything about them.

Are the ones shown on the attached image suitable for the G540 and can I use them for limit / home position as I did before with the lever type micro switches?

[john-100]

Hi Nicolas

yes ,
provided they have Normally Open NPN outputs

to connect several switches to one G540 input
wire the 3 switch wires in parallel

if the G540 is run from a 36V supply you can connect the +36V to the switch + terminal

if the G540 is powered from 48V
you need 6 to 36V supply for the limit switches - a 12V supply would be ideal

connect all switch outputs to the G540 input and

the switch negative terminals to the G540 ground / negative supply terminal


John

PS

now I have found the data for the switch -


wiring diagram with switch wire colours
Attachment 334962

[kolias]

Thank you John for the help. For the G540 I will use a 48VDC / 7.3A PSU and I will need another PSU for lights etc. which I have not decided yet but probably will be either 12 or 24VDC.

[kolias]

The mechanical is almost done and working now to complete a wiring schematic to connect all together. I have 4 questions now

The NPN sensors came with a 3 conductor (BLK, BLU, BRN) cable about 2 feet long. Looks like the conductors are 22AWG. Should I cut this cable close to the sensor and attach a shielded cable on each or these sensors are its ok to use non shielded cable?

The G540 has only 4 inputs for limits etc. but I need one more. My limits are
X+,X-,X Home to Pin 1
Y+,Y-,Y Home to Pin 2
A Home to Pin 3
Probe to Pin 4
But I also have the Z+ and Z-. Is there a way to combine some limits? Perhaps connect the Z limits to the Probe Pin?

Parallel connections (lets use the X axis as an example where I have 3 NPN sensors): By connecting the 3 conductors from each NPN in parallel we mean to connect the 3 Brown wires together and go to + of the PSU, connect the 3 Black together and got to G540 and connect the 3 Blue together and go to G540 Common. Is this correct?

Regarding the Common of the G540. I plan to take it to the earth ground and anything that needs to go to ground I will take it to that point. This will be the “star point ground” and the green wire from the 110VAC also will be connected there. Is this correct?

[john-100]

Hi Nicolas

you can connect all of the switches in parallel to use just one of the G540 inputs if you need to save inputs for other functions

but this means you can't see on the diagnostics screen which axis switch has been operated

how about
all + limit switches to input 1
all - limits switches to input 2
all home switches to input 3
and the probe to input 4


assuming you have a 12V supply for the proximity switches

connect all brown wires to +12V

connect all blue wires and the -12V to the G540 common (and star point)

connect the blue switch outputs to your chosen input

If your are lucky and can obtain some short lengths flexable metal conduit I'd leave the switch wires full length
this will provide mechanical protection and screen the 3 wires

powered from the internal +12V, the G540 opto isolated inputs should have good noise immunity

would it be possible to mount the switches in a Die-cast box ( 92x38x31mm ??? )
this could screen the wires and enclose the joint with the screened cables ??

John

[kolias]

Hello John

When you say “all+limit switches to input 1” and “all-limit switches to input 2” I don’t see how this will work because in Mach3 how do I tell Mach3 which pins the limits are?

I will get a 12VDC PSU but I’m waiting to see if I need another PSU for the VFD. I see in some threads that guys are using 24VDC to supply the analog power to the VFD to control the spindle ON/OFF. I want Mach3 to control the Spindle ON/OFF plus my cooling water pump. I plan to make a new thread just for this subject and then I will purchase the PSU’s needed

Flexible metal conduits are very expensive here John. Are you saying that because of G540 I don’t need shielded cables? The wires from the NPN are too short so I have to splice them.

Are these Die-cast boxes available for the NPN? Have not seen any so far

Nicolas

[john-100]

Hi Nicolas

Mach 3 (or4)
only needs to detect a limit switch has been tripped and stop

since it homes one axis at a time , all home switches can be on one input

John

[kolias]

I have Mach3 John

ok, I will keep that in mind

[john-100]

Hi Nicolas

this is the type of diecast box I'm thinking of

Attachment 340586

you can get ABS versions as well

do you have RS Components / Element 14 in Canada ?
or would you have to buy from the likes of Mouser electronics in USA or even Ebay or Amazon ???

John

PS

Metallic Enclosures | Newark element14 Canada

[kolias]

That looks pretty good John, I don’t know what RS Components / Element 14 is but I will search Ebay and Mouser

And do I just drill a hole to mount the NPN inside?
And what is the purpose? Just to kill the noise?

Thank you John

[john-100]

Hi Nicolas

the Radio Spares I first bought components from has changed name to become RS Components
a quick search reveals they are Newark Element 14 in Canada
Newark element14 Canada | Electronic Components Distributor
Metallic Enclosures | Newark element14 Canada

the die-cast box provides mechanical protection to the proximity switch and its wires
also screens the wires and any terminal block used to connect the cable to the switch wires

if you don't need the wires screened you can use a plastic box
a transparent box will let you see any LED indicator on the switch

it will depend on your machines design as to how many switches , if any need the protection

John

[kolias]

Hello John

I found Newark Element 14 and I bought from them before and I found a die cast box about $7.98 each. I need 7 boxes so my cost will be approx. $100.00 taxes / shipping included

Since this is the first time I will use NPN sensors, I will not install them in any box but down the line I can add the boxes and my preference will be a die cast box. My NPN’s do have a red LED but is located at the back of the sensor and I will assume it will not be easily visible

By screening I think you mean noise protection?

So when you say the G540 has opto isolated inputs does this mean I do not need shielded cables? As I said I do have to splice (extend) the NPN cable because they are not long enough to reach my control panel.

Before I used mini limit switches with the lever so when I was setting my limits (before any wiring connections) I will approach the part of my machine slowly and when it made a contact with the lever I will hear a click and I know the limits position was correct. Now with these NPN how do I know if the location of the sensor is good? Would a 9 volts battery work to activate the red LED?

[john-100]

Hi Nicolas

yes, by screening I did mean noise protection

for your initial tests a 9V battery should work OK
the data sheet I found did not indicate what the current taken by the proximity switch is
( with or without the indicator being on )

the cheapest way of connecting the switches to the cable will be to use heat-shrink sleeving
and solder the wires together - unlike PVC tape heat shrink sleeving does not drop off several months later

unless you have a VFD for your spindle or a plasma cutter emitting high levels of electrical noise
you should be able to take a simple approach to the wiring

what wiring did you use with the microswitches ?
if they were unscreened and worked OK , then I'd expect the proximity switches to work
how long are the cables ?

John

[kolias]

Never noticed before but there is a tiny label on each switch and among the Chinese writing it also has: LJ12A3-4-Z/BX, Supply 6-36VDC, Load 300mA. So my 9V Battery should do the trick

Yes I will use heat-shrink sleeving to extend the cables and since I do have a VFD and before I always used shielded cable I will use again shielded cable. The maximum run of NPN to my control panel is about 15 feet

Nicolas

[john-100]

Hi Nicolas

this may help -

Attachment 340628

John

[kolias]

That’s very good John, thanks

And since I can’t read electronic drawing properly I will assume it indicates how to have an LED light where I want it.

Much appreciated

[john-100]

Hi Nicolas

originally the diagram was intended to show the connection between the proximity switches and a G540 input
but at the last moment I added a LED indicator to see when a switch is operated
to simplify the wiring a ready made LED and resistor for 12V applications are available like this -
Attachment 340652


John

[kolias]

It will be handy to have this light

On my earlier posts I had mention if it’s a good idea to take the common (terminal 12 on G540) and connect it to the star point ground (I will have there also the green wire from the 110VAC and also connect all wires need to go to common / ground)

Is this a good idea John?

[john-100]

Hi Nicolas

any thing like this ?



John

[kolias]

That's excellent John, thank you

Nicolas