Are there active-low optical endstops out there??

curtisb1986

So everything I've read in Duet literature indicates that an optical switch should operate in an active-high manner. That is, the same way a NC switch would behave.

I have in my possession two different optical switches, one with traditional 3 pin VCC, Signal, GND pinout., the other with a 4th pin labeled "L" (I won't be connecting that pin for this setup, as I'm not entirely sure what it does yet).

On both of these switches, after connecting GND and 5V leads, the signal pin and GND pin are not connected. When the optical switch is tripped, the circuit between GND and Signal pins is completed and resistance measures 0 ohms.

Is that not what a "Normally Open" or "active low" configuration would look like?? As in, active-low is the LOWer number of ohms, and active-high the HIGHer number?

What am I missing?

Thanks in advance for any help!

dc42

@curtisb1986 yes that's how an active low optical endstop switch would behave. Most optical endstop switches consist of a slotted opto switch and two resistors. If your switches have additional components then they might well have active low outputs.

curtisb1986

@dc42 ok, but these are just standalone switches.

If I'm understanding right, I can run 5v on the board to vcc on the switch, Gnd to Gnd, and signal to ioX.in

This should just give the switch power and allow the GND and ioX.in pin to behave like a regular normally open switch, yes?

And on rrf3.x I shouldn't be using M574 with an s0 modifier anymore, correct? Just an exclamation point in front of the pin name?

dc42

@curtisb1986 said in Are there active-low optical endstops out there??:

@dc42 ok, but these are just standalone switches.

If I'm understanding right, I can run 5v on the board to vcc on the switch, Gnd to Gnd, and signal to ioX.in

This should just give the switch power and allow the GND and ioX.in pin to behave like a regular normally open switch, yes?

And on rrf3.x I shouldn't be using M574 with an s0 modifier anymore, correct? Just an exclamation point in front of the pin name?

Yes, that all sounds correct to me.

curtisb1986

@dc42 here are some photos of the switches. I'll take video of the active-low behavior soon. I'm very confused about this active-low/high thing.

If I understand your original reply correctly, an optical switch that operates in an active-low manner would have to be mounted on a PCB or have some other connection outside of the switch itself, yes? That's definitely not the case here, as you can see by the photos:

curtisb1986

@dc42

dc42

@curtisb1986 yes those contain electronics and are active low (NPN) output if the L terminal is left unconnected. Datasheet athttps://assets.omron.com/m/4709f5d376a05245/original/EE-SX47_67_Datasheet_en_201404_E64I-E-01-pdf.pdf.

dc42

@dc42 said in Are there active-low optical endstops out there??:

@curtisb1986 yes those contain electronics and are active low (NPN) output when the light is interrupted if the L terminal is left unconnected. Datasheet athttps://assets.omron.com/m/4709f5d376a05245/original/EE-SX47_67_Datasheet_en_201404_E64I-E-01-pdf.pdf.