Optical Sensors w/C3D Mini Board help please

Machine: ULS 25-E

Board: C3D Mini

Firmware: Smoothie

Problem/ Question: I am converting an old ULS laser to cO2 and am installing the Mini board I had laying around. I want to use as much of the stock components from the ULS with the Mini board and I would like to know how I would connect the optical homing sensors to the board? Here is the data sheet for the ones that are in my cabinet for x and y homing. https://omronfs.omron.com/en_US/ecb/products/pdf/en-ee_sh3.pdf

Any and all help is greatly appreciated!

Are you saying that these sensors are the things that come in the stock ULS-25E? I ask because we are all too familiar with that machine.

I dealt with this type of sensor in the FSL Gen 5 Conversion. Fslaser 5th gen conversion

If it’s the raw sensor as shown then you’ll want to connect the left side (LED) to 5v and Gnd through an appropriate resistor, and the right side would go to Sig and Gnd. All of these pins are available on the endstops connectors row on the bottom of the board. There is a pinout diagram and other Mini resources linked here: https://cohesion3d.com/getting-started-old/

If you need me to get into more specifics, please let me know and send pictures so I can confirm what we are looking at.

Thanks Ray. Yes, these are the stock sensors. It is just the sensor and a pigtail. Which resistor would I need to use? Sorry, I am not very fluent with those :stuck_out_tongue_winking_eye: There are also some magnetic safety switches but I am not going to mess with those for now. I am trying to get this running so I can get back to work with Covid-19 face shields so I don’t have to use the K40 O_o

Hi Aaron, I did a quick calculation and it looks like an 82 ohm resistor would work well to drop the 5v down to 1.2v needed for the emitter in the sensor. Hopefully you’ve got a few on hand to get things working.

Higher values should be ok: 120 and 470 ohm are common values that have also worked in similar applications.

If you can’t source any, let us know, we have some here.

(The ULS-25E is a workhorse of a machine! We’ve got one at my makerspace we upgraded to 50 watts and it’s been pretty solid over the years.)

I have not tried those endstops yet as I am still trying to figure out WHY my x motor will only move in 1 direction. I have even swapped the cables to motors and also does it to other motor on that axis. I have tried other stepper drivers and still the same thing. I even flashed firmware again in case it was corrupted. I also redid the config file and still, nothing changed :confused: I need to get this up and running so I can supply PPE items to the community :frowning:

So tie the 2 grounds together (K/E) and then the others to which pins? Where does the 82Ω resistor go?

Correct, tie the grounds (K, E) together and those can connect to the GND for an endstop. The C should connect to the Sig for an endstop, and the A should connect to the +5V for an endstop with the resistor inline to drop the voltage.

Using the diagram of the Cohesion3D Mini board above showing the endstop connections, here’s what you want:

C = Sig (Green)
K, E = GND (Blue)
A = +5V (Orange)

Thanks. Would they be considered NO or NC then?

I believe it will be NO, but once you’ve got one connected you can run the M119 end stop tests explained at the link below. You’ll be able to see if triggering the sensor produces a 0 or a 1 and then if needed make any changes in the config file so it works properly.

An NPN phototransistor will be active low; that is, breaking the beam causes the CE junction to go low. There will be a +5V signal at SIG normally and 0V when interrupted.

Also, minor pet peeve - a resistor doesn’t limit voltage, it limits current :slight_smile:

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Oh, right! Would it be more correct to say that the resistor limits the current, which causes the voltage to drop?

The only thing that causes the voltage to drop is the P-N junction in the diode (an LED’s voltage drop is equal to its forward biasing voltage). That is to say, LEDs are mostly current devices, but require at least a certain voltage to turn on fully. Below that voltage, the P-N junction is in the linear range and current will be proportional to voltage. Above that voltage, the current begins to shunt across the diode and will negatively impact the diode’s lifespan (it’s typically dissipated as heat instead of light). This is why the current limiting resistor is required.

So is it ok to use the 82Ω resistor as mentioned above? Will I also have to do this method if I wanted to use them with a Ruida 6445G DSP controller?

Yeah, 82 ohms is fine. That puts ~21.5mA across the junction which should be enough for reliable operation.

As far as the Ruida goes, yes, you’ll have to limit current to the optoemitters somehow with that solution as well. I’ve gotten optoelectrical sensors working with an RD6445G before - I remember there was something tricky I had to do and don’t recall what I ended up doing. In any case, discussing how to make competing products work is venturing pretty far into off-topic for this forum :slight_smile:

Well considering my C3D Mini is not working properly and no one got back to me, I have no choice but to get a different controller since I have to keep making items for this Covid-19 PPE stuff. So yea, if you can remember what you did to get YOUR non C3D product working with the optoelectrical sensors, HMU, send me an email, message, PM/DM hell, you can even face time me if you want even though I cant stand apple as much as this Mini…

P.S. I use Android

What do you mean no one got back to you? We’re trying to help you out and get it working right now … Is there something besides the endstops that isn’t functioning?

I wrote an email to Ray (I suppose) because my Mini, no matter what I did, the x axis would only turn in 1 dir. I changed wires, drivers, motor, reuploaded the FW and config from a fresh file and STILL only moves in 1 dir no matter which way I tell it to go :confused:

He means he sent an angry/ frustrated sounding email with complete lack of detail (and a video titled “C3D Mini acting like a POS!”) after close of business on Friday and hasn’t received a response yet. The response would have been, all of our support is done through the forum, our staff will be happy to help you there.

In order to help you with this or any matter, you will need to provide more information, like pictures of your board and wiring, and actual details, instead of “I tried a bunch of stuff and it still doesn’t work”.

And remember that you are receiving help from my staff on hardware that we have not made for over a year and a half, and to the best of my knowledge, you did not even purchase from us directly in the first place.

I’m also busy running a 3D Printer farm to do PPE. We’re all frantic and going at 100 miles an hour here. Try to take it easy.

Well Ray, I am glad you are doing something to help the community as I am also and the downtime doesn’t help. And YES, the Mini IS acting like a POS. And YES I did NOT buy it from you but it was purchased from you regardless. I suppose the support only goes to the original purchaser or are you agitated that I purchased it from someone that is supporting the better clone of your board (Bet that changes my support options)?

With that said, I had help from Arthur (Smoothieware creator) over the weekend and he himself told me that he is stumped after we went over everything. I am not sure what wiring you would want to see since I only had it connected to power, USB/Lightburn and the motors. Nothing else was connected as I am going from the “ground up” getting things to work as I move forward. So what would you like to see? I am only willing to connect the board back up if there will be a resolution from this besides confirming that I have a paperweight because I will take my time/money elsewhere that is more deserving of it at this point.

As I said, we are happy to help people that are being respectful, compliant, and put effort into asking for help.

Being hostile is not the right way to ask for help.