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I am a beginner and I know what I did is gonna sound terrible.
I have a Mk3/4 Planet CNC controller and I connected NC PNP inductive proximity switches to LIM1, LIM2 and LIM3 inputs.
The problem is that I did that without any optocouplers. I connected the brown wire to +12V, blue wire to GND and black wire directly to the input.
It seems like I fried the inputs. Is there any way to fix what I did?
If I have read your post correctly
The NC PNP inductive proximity switches will of
pulled the Mk3/4 Planet CNC controller limit inputs up to +12V
destroying the inputs
The only solutions I can see is either
use the inputs IN1 to IN4 if the PlanetCNC software will let you
or replace the MK3/4 control board
Contact Planet CNC to see if they either repair the boards or offer a discount on a replacement
John
Thank you John for your quick response.
I will contact the support to see whether they can fix the board.
Can I use this PC817 module to wire the inductive switches: https://www.aliexpress.com/item/32836147946.html
yes that PC817 module will work
the circuit only shows 1 of the 4 opto-isolator circuits on the board
Attachment 425142
removing the red jumper will isolate the proximity switch 12V supply GND from the Mk3/4 Planet CNC controller input GND
when the limit switch is closed
the PC817 modules LED will be on and the PC817's photo transistor will be switched on
grounding the Mk3/4 Planet CNC controller limit input
John
Most likely one of the buffer chips burned out. SN74AHCT244 (hb244) You can change the chip itself which goes to the conclusions of "LIM".
Thank you both for your responses!
I send the board out for repair to PlanetCNC.
Your scheme makes perfect sense to me John, thank you!
There is just one thing that is still bothering me. If you look at the original optocoupler module from PlanetCNC It is also connected to +5V pin on the controller. Please someone explain to me why that is necessary. Shouldn't the module also work if +5V is left unconnected?
Would this board work as well? This is the board that I can get locally within a few days. I guess that I might need to change the resistors with lower values so it would work with 12V.
I know it seems like I am making it more complicated than it needs to be, but I am just trying to get a better understanding.
the PlanetCNC opto-isolator board has a dual opto-isolator IC that has more than the 2 LEDs and the 2 photo transistors a 2 channel version of the PC817 module from post 3
Attachment 425420 Attachment 425424
HCPL-2503 on the PlanetCNC opto-isolator board data sheet
Attachment 425422
John
PS
the link to the second board you can get locally goes to the planetcnc module the first link goes to
Ah, sorry! This is the board that I can get locally: https://www.banggood.com/24V-To-5V-4...r_warehouse=CN
Thank you for providing the datasheet. This goes beyond my understanding of electrical circuits but I guess the +5V connection is there for noise reduction?
using the photo of the board and the HCPL data
PlanetCNC opto-isolator module circuit
Attachment 425432
the banggood board probably will if you get the correct version
I'll have a look to see if I can find more details
John
this banggood board
Attachment 425434
will work when connecting 24V NC PNP inductive proximity switches to the
5V Mk3/4 Planet CNC controller inputs
you can see it has 3K9 resistors (marked 392) to limit the current through the LED input indicator and PC817's LED
assuming the volt drop across the LED is 2V
22/3900 = 0.0056A = 5.6mA which looks OK
with the output side powered from a +5V supply the opto isolator output will be safe to connet to the Planet CNC controller limit input
each PC817's NPN phototransistor has a 10K pullup resistor (marked 103) / collector load connected to the +5V supply
the output LED's and power indicator has a 510 ohm resistor (marked 511) to limit the current from the + 5V supply
5V - 2V across the LED = 3V
3/510 = 0.0056 A =5.9 mA
John
I'm sorry if I open a older post...
this is the same, correct?:
https://www.amazon.it/Optoaccoppiato...662255&sr=8-12
thank's
Nino
Hi matey. NO!.Quote:
Originally Posted by Clyde_IT
That board is no where near the same. It turns out it has all the grounds linked together throughout the board. I tried one as a simple switch but if the trigger is on the low side of connection (negative) the entire board lights up even if only 1 isolator is connected.
What you need is a board with both +/- input options with seperate positive entry. Also with option to choose between pull up or pull down when you output it.
I unequivocally recommend these ones below for either mechanical or inductive, 2 or 3 wire switches.
I have inductive switches inputting into this one at 24v and then it outputs 5v low to my controller. I will use no other board type again.
https://www.aliexpress.com/item/4000...57834c4d6Ncn7G
You can choose your input/output voltage requirments and npn/pnp output type depending on your cnc controller inputs.
(I think I have a wiring dia drawn up for this using proximity switches somewhere if you get stuck)
This one may also work fine:
https://www.aliexpress.com/item/1005...c00XFWXFL&mp=1
Choose your input voltage you need. Output shows it can run load from 1.8v upto 24v as is.
I have both of these board types but the first one is well worth waiting delivery for.
Haven't fully tried the bottom one yet.
oh, thank's! You prevented my mistake!
The only problem is I can’t wait that long... I've to find something similar in a European market (Italian is better) for a delivery up 4-5 days.. :(
I'll try to search for it..
Thank's again
Nino
Ok, now I think that it's correct :)
https://www.amazon.it/AILOVA-Convert...0&sr=8-18&th=1
Quote:
Originally Posted by Clyde_IT
That should work fine.
They look to have a good supply of that version all over the site.
Handy circuit diagram on this one:
https://www.amazon.it/optoaccoppiato...85367&sr=8-234
They also have:
https://www.amazon.it/Isolamento-Del...85237&sr=8-152
I find these types of relay module useful too for switching things on/off. You can use either positive (high) or negative (low) triggers on these and just change the jumper to suit.
https://www.amazon.it/Condensatori-S...&sr=8-181&th=1
Perfect. They delivered and I tried quickly, it seems to work very well. Thank's again
Nino