C3 Board Optical Switch Issues

[Starleper1]

I'm using the CNC4PC C3 board for my axis home/limit switches, and I'm getting strange results. I have the XYZ all connected to the sensor input, and when a sensor is triggered it creates an output to the BOB input. This is the 'normal' operation.

Now this is where it gets weird. Two of the three sensors work as expected with no problems. But when I connect the third sensor it some how disables the two other sensors leaving only the third sensor working. I've been pulling my hair out trying to figure this out, with no luck.

If I disconnect the third sensor, then the two other sensors go back to normal operation. I ordered a replacement sensor but had the same result.

Any of you electronics guys have any ideas?

[Al_The_Man]

Did you substitute one of the ones that are working in the non working spot, to eliminate the sensor itself?
How are they connected?
What type of sensor?
Al.

[Starleper1]

Did you substitute one of the ones that are working in the non working spot, to eliminate the sensor itself?
How are they connected?
What type of sensor?
Al.

Yes it doesn't matter which axis, it's always the same sensor.

I have them connected as the C3 manual shows.

The sensor is an NTE3100

[Al_The_Man]

If it is not the sensor, then it could be the wiring, how about connecting the sensor at the C3?
Al.

[Starleper1]

Already tried that. Same result. It has to be something with the sensors.

I took a couple voltage measurements , and I'm hoping this will give you an idea of what could be going wrong here. First I took measurements with the "working" sensors connected in the un-triggered state. From terminal "C" to terminal "E/K" I get 1.95VDC. From Terminals "A" to terminal "E/K" I get 1.15VDC. With the working sensor in the triggered state, from terminal "C" to terminal "E/K" I get 3.5VDC. "A" to "E/K" remains the same at 1.15VDC.

Now with the "non working" sensor connected, in the un-triggered state, from terminal "C" to terminal "E/K" I get 0.20VDC. Terminal "A" to terminal "E/K" remains the same as the "working" sensor in both triggered and un-triggered state at 1.15VDC

[Al_The_Man]

The pdf details are a bit scarce!
The transistor side is + and E and the diode side is + and D.
There are a couple of ways to connect and it depends on whether the P.S. is common for both sides or separate?
There is a resistor required for each side value depending on the voltage, and the E & D can be the common(s) and the resistors on the + terminals, which is just one of the ways to connect.
Emitter common and collector output or vice versa.
D would be the cathode or K.
The way you have it hooked up and powered would help?
Al.

[Starleper1]

This is how it shows in the PDF manual of the C3. I have all the sensors wired the same.

[Al_The_Man]

Look like you might have a damaged sensor?
Al.

[Starleper1]

I thought so too, so I ordered another one. I ended up with the same exact results.

It's driving me nuts.

I appreciate your time with this by the way.

[Al_The_Man]

BTW, I never order NTE unless I can't help it, they are a substitute semi company, and their prices are typically 200% to 500% more than the original make.
There are many versions of these that I would have sought out first before going NTE.
You can also get Light-ON or Dark-On versions.
Al.

[Starleper1]

Well the sensors came with the board, so I didn't have a choice. I wish I knew what was going on here.

[john_100]

to me it looks like the diagram in the manual is wrong !


I'd expect the photo transistors Emitter (E) and the LED's cathode(K) to be connect to the terminal E/K

the photo transistors Collector (C) to terminal C

and the LED's Anode (A) to connect to terminal A

with close up pictures of both sides of the board
I'd be able to help with detailed tests if needed

John