[Dbl_Tap]

I know jut enough to be dangerous when it comes to electronics and need a guide for dummies on this.

I am using OPB830W11Z slotted photo optical sensors for homing my CNC. https://www.digikey.com/en/products/...30W11Z/1637175 Been using them for almost 10 year. Now that I'm switching my controller to a Mach3Bob (MB3 with ESS) I need to relearn a few things. I can't tell if they are NPN or PNP which is kind of important for how I connect them to the MB3. I'm sure trial and error would work but I'd rather do it right the first time. I still get confused on which is which and which means normally open and closed. Again I need a for dummies guide

Also on my current setup I have to use small break out boards for these sensors to then connect to the main controller board. Do I need separate BOBs for the MB3? I don't think I do but again want to make sure.

Thank you in advance.

[Jim Dawson]

It would appear that they are NPN

https://www.ttelectronics.com/TTElec...830_OPB840.pdf Look at the last page

[Dbl_Tap]

Thank you Jim. I have that data sheet and I figured something on there tells me but I'm not smart enough to know what it was. Which part tells me that for future reference?

[Jim Dawson]

This picture. This is the symbol for a NPN photo transistor output

[Dbl_Tap]

Perfect, thank you. Looks like we are in the same neck of the woods as well. I'm tired of this cold!

[Jim Dawson]

Perfect, thank you. Looks like we are in the same neck of the woods as well. I'm tired of this cold!

Me too It's too cold in the shop to work.

[Dbl_Tap]

That's why I'm inside designing things in Fusion and asking questions on here lol

[Al_The_Man]

Like many Opto's They can be used either way, IOW you can place the pull-up or pull-down on either the collector or emitter, this gives both options.
The output is on the side of whichever has the resistor.

[Al_The_Man]

Here is an example.

[Dbl_Tap]

Here is an example.

Thanks. Which configuration is the least susceptible to issues/noise/false trips?

[Al_The_Man]

Electrically they are just about the same, it just gives you the option of pull-up or pull-down.

[Dbl_Tap]

Electrically they are just about the same, it just gives you the option of pull-up or pull-down.

Great thank you.

[Al_The_Man]

Also check your input for opto isolated input, you may be able to eliminate the resistor by using your input device in place of the pull-up/down.

[Dbl_Tap]

I am almost positive I don't need anything to connect the limit switches and slotted photo sensors to my MB3 if I'm reading pages 16-20 correctly. Again I know just enough to be dangerous so I could be completely wrong. https://cncroom.com/wp-content/uploa...nual-E20R2.pdf

[Al_The_Man]

Right yes, as in my last post, you can use the input Opto as the load for the external limit, IOW no pull-up or pull-dwn needed.
Page #17.

[maxspongebob]

Just a quick note to demonstrate why one might be better than the other.

It is always a good idea to configure your circuit such that if the cable breaks or becomes disconnected the limit switch will show as active. In this case, either circuit will do this. Also it is important to make sure that the circuit you design is tolerant of a short. In this case you may not want to use the pull-down circuit because it is vulnerable to, in a shorted condition, connect the unlimited +V to ground. Shorting your power supply rail to ground will affect the entire BOB and could cause physical damage. The resistor in the pull-up circuit will limit damage in a shorted condition.

These factors show why it is often preferred to use NC, Normally Closed, switches and NPN sensors for limit sensing.

Just my $.02

[Dbl_Tap]

I've been running new wiring to everything and am just now getting ready to connect to the board. Of course, I thought I had it all figured out and now I'm not so sure.

https://cncroom.com/wp-content/uploa...nual-E20R2.pdf

My limit switches three wire sensors. My last setup had all limit switches connected together which I planned to do for simplicity and less wiring. The board just needs to know the machine hit a limit, it doesn’t care if it hit the Y+ or the Y- independently.

SO for the limits:
Brown wire is power which will come from the 24v output on the board. I can understand that.
The black wire goes back to an input, lets say X203 on my board.
The blue wire I’m assuming would then connect to the 0V in the same port section?

Assuming that’s correct the homing switches get me a little more confused on the connections. They are four wires.

Black is the cathode. Now does that mean it’s a ground or is it the 0v? Can all of these be combined? I’m thinking so if they are 0V because I’d run out of those really fast on the board.
Red is the anode which is power so that’s the 24v output. Easy again. All these can be combined.
White is the collector and on my old board combining them was the way they were wired but I don’t know what this connects to on my board.
Green is the emitter and don’t know what it connects to either.

I know I’m being dense but this stuff isn’t my forte at all. I do much better with mechanics so I love being told put this wire in this spot on the board.

Thank you again for putting up with the dumb questions.

[Al_The_Man]

You are confusing/mixing valve (Tube) terminology with solid state.
What are the part No.'s of the switches or a link?
OK I see your first post, will look them up.

[Dbl_Tap]

The limit switches are SN04-N

[Al_The_Man]

OK you will need a resistor in series with the diode which will go from the the +ve through a resistor to the top (anode) of input., the other cathode side goes to GND.it has to limit the current to 50ma max.
So the value depends on the source voltage provided.
The output can be connected direct to your input and configured as previous diagrams as sink or source.
https://www.nutsvolts.com/magazine/a...upler-circuits