[jimskeet]

if you must connect multiple normally closed NPN sensors to one BOB input this is one possible solution



John

Hmm that seems a little complicated but I guess I understand the wiring and the components.

I was thinking something like this, but since none suggested it, I guess it cannot work like this?


- - - Updated - - -

you should see 12.xx on the meter with red meter probe connected to brown and black meter probe connected to blue wires of the sensor . when the axis is off the home position and led lit you should measure less than 1 volt across GND and PIN 12 terminal on the BOB this should measure the same for all sensors and there associated input pin

Great. I will test it next time.

[john-100]

another NPN sensor adaptor

Attachment 386756


you can not connect NPN sensors in series

but you can connect normally closed PNP sensors



John

[jimskeet]

Cool.
I could also just use simple NC switches as limits and be done with it.

[Nleo22]

If this is already standard knowledge then my apologies... Standard proximity switch wiring is brown V+, blue V- & black signal It depends on your sensor voltage ratings but for example if you have a NPN NO sensor that operates on 10 to 30 volts and are using 12v to the brown V+ and have connected the blue to V-/ground... the black signal wire will output 12v (or whatever 10v-30v voltage is supplied to the V+ brown wire) when no signal is detected. When the sensor detects metal the signal wire voltage drops to zero (or close to zero). Most breakout boards are opto isolated from the parallel port which is their typical purpose and have built in pull up/pull down resistors for the input pin signals but, if your breakout board cannot accept a signal voltage greater than 5v at it's input pins, you need to use resistors and make a simple voltage divider to drop the signal wire voltage to 5 volts. Some breakout boards can accept 12v or 24v at the input pins which make things easier. The reason the sensors don't all use lower voltages is the higher voltages are less susceptible to noise causing signal issues. If your sensors have a resistor built in them, then you need to measure the built in resistors resistance and then add the appropriate size resistors so that combined the total drops the voltage to the appropriate voltage that your BoB can accept at the input pins.

Man you're right on this. I got roko sn04 npn-no 5-36v rating, the sensor alway out 5v pull from ess-c25, and the signal wire to Bob won't engage, because sensor 5v doesn't drop continue open... really frustrating till now I still haven't figure out yet, if you have a chance please help me. Or I might have to buy pnp-NC sensor.

[john-100]

is this how you connected the sensor and ESS-C25 ?



what is supply voltage connected to the SN04N ?

and what is the value of the pullup resistor you used ?


John

[Nleo22]

I using the meanwell 5v/2.0a, to power the ess, and sn04N pull the power straight from ess-c25 bob terminal keep it simple I think it all 5v.
I brought the resistors kit from amazon it have majority of size, because I don't know resistor ohm laws =( no club about electronic stuff, really need some training =D
as you see in the image my sn04n always powered led without touch the metal plate. Im frustrated almost two weeks now, i can't solve the problem.


Attachment 405688
Attachment 405690
Attachment 405692
Attachment 405694
Attachment 405696

[john-100]

after a quick search for the SN04N data sheet I only found one in chinese !!

the one thing I could read is the sensors supply should be between 10 to 30V

Attachment 405714

from your photos I can not see what pull up resistor you have fitted (if any)

if your sensors do work with a 5V supply
I would reduce the pullup to 100ohms

Attachment 405716



John

[Nleo22]

I check all 3wires from sn04-n with multimeter to find internal ohm,
brown (+vdc) & blue (gnd) = 13.27k ohm
black (input) & blue (gnd) = 23.2k ohm
brown (-vdc) & black (input)= 9.95k ohm
================================================== ========================

HOLLY SH thank you man. after I add 100 ohm to Brown and black wires sensor home switch work... it triggered. I went check the current between blue and black with sensor triggered got 110vdc why ?
how do you know 100ohm can i make the trigger volt lower?


Lmao I ordered 3x pnp-nc other day before I checked this reply, I didn't know the one I got right now it actually still work, after you help me. man I really appreciated for the help bro. I guess pnp-nc for limit when it arrive.

[john-100]

not knowing the part numbers of the LED indicator and opto-isolator on the ESS board
when the sensor is connected directly to the ESS
I made the assumpion the voltage at the junction of the LED indicator and 330 ohm resistor will not change from the 2.69V I calculated earlier

the 100 ohm resistor limits the current through the SN04N when it grounds the ESS input

when the SN04N output is off the current flowing into the ESS board will drop about 0.55V across the 100 ohm resistor
so the ESS input will be at about 4.455V.


Attachment 405796


a quick calculation shows that when the SN04N sensor powered from a +5v supply
a 100 ohm pull up resistor will also work when connected to a C25 board's input

( a 1000 ohm resistor will also work but using a 100 ohm resistor has the advantage of reducing the
input impedance helping to reduce the effects of electrical noise picked up by the sensors wiring )

Attachment 405798

PS
NPN open collector outputs can only pass current to ground and not supply current from the sensors positive supply

( sensors with PNP outputs can supply current from the positive supply but are not able to switch to the output to ground )

john

[Nleo22]

1# which software or app that you use to calculate for the right ohm?

2# I also ordered this pnp-NC
http://vi.vipr.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=381489388907&t=1527063981000&tid=10&category=57520&seller=mdflyelectronics&excSoj=1&excTrk=1&lsite=0&ittenable=false&domain=ebay.com&descgauge=1&cspheader=1&oneClk=1&secureDesc=0

Which application good for homing npn-no, limit pnp-nc?
Or homing pnp-NC, limit npn-no?

[john-100]

2)
after reparing various video , balanced audio and multiway camera cables experiance tells me
the odds are higher that a sensor wiring fault will be a wire going open circuit

so I would use a sensor with a normally closed output -
the problem with N/O outputs you don't know a wire has broken and the control is not going to see the switch close

in your case with the sensor connected to an ESS or C25 input
use a sensor with an open collector PNP output

when a N/C PNP sensor is connected to a 5V supply you don't need a resistor connect the ESS input to work
( but a 100 ohm resistor between the PNP output and the ESS input will limit the fault current if the ESS input is shorted to ground )



you may find when connecting a N/C PNP sensor to the C25 input
a 100 ohm pull down resistor may be needed between the ground and C25 input to reduce the input impedance and make the C25 less sensitive to stay pickup

( if you have a 100 ohm resistor in series withe the sensor output to limit the current if the output is shorted to ground
then the pull down resistor if fitted will need to be about 270 ohms to ensure the 74HC14 input is at more than 3.5V when the sensor output is at +5V)


1)

I did not use any app to find the correct value of pull up resistor in my original diagrams

using a mixture of experiance and reverse engineering the ESS and C25 inputs

going by the chinese data I found for the SN04N sensor
the maximum current the sensor can sink to ground is 200mA

with a 100 ohm pull up resistor the SN04N sensor is going to sink 50mA that flows from +5V when the sensor NPN output is switched on
the 100 ohm resistor only dissipates 0.25W

the 74HC14 IC on the C25 board is a CMOS IC has a high impedance - the low impedance pullup resistor (100 ohms)
will help to reduce any stray voltages picked up by the sensor wiring

as an alternative
using a 1800 ohm pullup will form a potential divider with the 4700 ohm resistor shown in the C25 manual

result is the 74HC14 input will be at 3.6V when your sensors NPN open collector transistor is off

I used 0 to 30% of the 5V supply as a valid low level logic = 0 to 1.5V
and 70% to 100% of the 5V supply a a valid high logic level = 3.5 to 5V




looking at the SN04N sensor being connected to the ESS input
the diagram in the manual indicates 7mA will flow into the input through the 330 ohm resistor , passing through the LED indicator and the opto-isolators input LED

using ohms law, 7mA through the 330 ohm resistor gives you 2,31V across the resistor
subtracting 2.31 from 5V gives you across the two leds 2..69V

adding the 100 ohm pull up resistor to 330 ohms gives you 430 ohms

I assumed the volt drop across thetwo LED's will remain at 2,31V
so dividing 2.69V by 430 gives you 6.25mA through the LED's instead of 7mA
I do not think a reduction in current of about 10% will stop the circuit from working

John

[Nleo22]

pnp-NC arrived tested it seem work without 100ohm.
how do I wire in series for limit switch.

[john-100]

Hi Nleo22

this morning I have been looking at the sensors sold by CNC4PC

the wiring examples for theC10 BOB and A60 PNP NC sensor

shows sensors wired in series with the first sensor powered from +5V and
its black output wire connected to the brown + supply of the next

the last sensors black output goes to the BOB input with a pull down resistor

all blue - supply wires are connected to BOB's GND


Attachment 406340

the C25 input is like the C10 with the jumper set to pull down




this is the inverse of what happens with sensors with N/O NPN outputs
NPN outputs can only sink current to ground and not source current from the positive supply like
sensors with PNP outputs



John

[gshowler]

Hi

I am trying to install proximity switches to my CNC and I have the same breakout board as the one in the pictures. JK02-M xx. My proximity switches are NPN normally closed, the wiring on them states the signal wire connects to positive, not ground has the normally open ones are. My question is how do I connect the Prox sensors to the limit switches?

Many thanks Gary

[john-100]

Hi Gary

this note -

"My proximity switches are NPN normally closed, the wiring on them states the signal wire connects to positive,"

does not read correctly for NPN proximity switches

can you give more information

whats the part number of your proximity switches

open collector NPN switches can only ground the output when closed

open collector PNP switches outputs are connected to the positive supply when closed

Attachment 429740

John

[gshowler]

Hi John

Thanks for getting back so quickly. Here are some picture from the label on my proximity switches.
Gary
.

[john-100]

Hi Gary

looking at the first photo
the diagram on the proximity switch is clearly a NPN switch

a quick web search for LJC18A3-B-ZAX confirmed the switch is a Normaly Closed NPN proximity switch


switch data

Method of detection: Capacitive
Output: 3 wires, normally closed,NPN
Shape: diameter 18 mm cylinder
Detection distance: 10mm
Operating voltage: 6-36V DC

Attachment 429772



If you have this BOB I reverse engineered while fault finding

Attachment 429774

you can connect a single LJC18A3-B-ZAX to a BOB input like this



this is OK when you have one home switch on each axis

if your want to have two LJC18A3-B-ZAX limit switches per axis
you will need an extra circuit to interface multiple switches to a BOB input

with this BOB its easier with PNP proximity switches

John

[john-100]

If you have this BOB

Attachment 429780


you can use the wiring diagram from post 4 to power the LJC18A3-B-ZAX limit switches from 12V

Attachment 429782

note - this only work with one switch connected to each input without adding
additional components

how many switches do you need to connect to a BOB input ?

John

PS

diagram from post 15 with wire colours changed to agree with proximity switch wires

Proximity Sensor Wiring v3
Attachment 429784

[ronald44181000]

I've probably gone through more than a few reams of papers on this subject and seen dozens of hours of videos and I'm still left with the Basic Question of. What would be the Correct Resistor to use between the Brown V+ wire and the Black Load Sensing wire of my DC Capacitive Sensors LJC18A3-B-Z/AX 6-36V????????
They are rated for 6-36V DC and I want to use them with my Gecko G540 and either it's 48V Power Supply or a 24VDC Wall Wart.

Is there anyone here who can point me in the Right Direction with some Basic Instructions???????????

[davida1234]

1 kOhm worked for me.