I've just taken delivery of a Metrol contact switch via Misumi EU for use with my proposed sliding mount (claimed repeatability 0.001mm at switch point of 0.3mm). I didn't particularly want an LED but that's how it came. There is no board or other components and as near as I can make out (the instructions are in Japanese), the LED is just in series with the switch contacts (normally open I'm afraid). So I'm guessing that I'd just connect the brown wire to 3.3v and the blue to Stp and set M574 to active low. Is that correct?
Also, there are some Japanese characters that seem to indicate that a series resistor is needed but I think that's only for 24v systems and I'm safe to ignore that with 3.3v logic. Is that also a safe assumption?
Quick update to this. I've got some English info from Misumi. The contact rating is 5 to 24v 10mA max (with LED) resistive load. Then a bit further on I have " For load within the switch rating or installation onto a PLC, current limiting resistors are not necessary as long as the current is about 7mA"
So am I OK to connect this directly to the Duet as detailed above?
Can you bypass the LED? If so then you can just connect the contacts to the E0 endstop pins in the usual way. Otherwise, I suggest you connect it between the In and Gnd pins of the Z probe connector, with a pullup resistor of about 220 ohms to 1K between In and +3.3V, use Z probe type 1, use the I1 parameter in the M558 command, and set a suitable trigger level using G31.
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Thanks David. The LED is kind of moulded in to the lead so the only way to bypass it would be to cut it out which no doubt would invalidate any warrantee. I'm a bit reluctant to do that as it cost me 34 quid. I'll try your plan B. Ian
Sorry to be a pain again. I was rather hoping that I could retain your IR probe in case my sliding mount doesn't work out. What I had in mind was to leave that connected to the Z probe input but connect this switch to the E0 input and select mode 4. That is to say, it'd be cool if I could have them both wired and switch between them in my config. I'm assuming from you reply that this is not possible but can you just confirm that that is the case please.