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 - - -
Great. I will test it next time.
Cool.
I could also just use simple NC switches as limits and be done with it.
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.
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.
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
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
John
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.
Last edited by Nleo22; 11-10-2018 at 08:15 PM.
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.
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 )
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
Last edited by john-100; 11-11-2018 at 08:04 AM. Reason: add PS NPN open collector outputs verse PNP opec collector outputs outputs
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?
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
Last edited by john-100; 11-11-2018 at 12:05 PM. Reason: correct some typos and recalculate for 1800 ohm C25 pullup
pnp-NC arrived tested it seem work without 100ohm.
how do I wire in series for limit switch.
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
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
Last edited by john-100; 11-21-2018 at 07:46 AM.
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
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
John
Hi John
Thanks for getting back so quickly. Here are some picture from the label on my proximity switches.
Gary
.
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
If you have this BOB I reverse engineered while fault finding
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
If you have this BOB
you can use the wiring diagram from post 4 to power the LJC18A3-B-ZAX limit switches from 12V
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
Last edited by john-100; 10-23-2019 at 07:08 AM. Reason: add PS
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???????????
1 kOhm worked for me.
BryggaCNC.com