Looking for ideas to combine 2 probe inputs to one on Tormach

[Mike R]

So I've now confirmed I am not an electronics genius and I need some help.
Situation- the Tormach has a single input for probes (toolsetters and touch probe), can be set active or passive in the PathPilot setting page.
I have a tool setter that is "passive" (just a switch) and its configuration is NC - confirmed continuity when not trigger, open when triggered).
I just acquired a new touch probe that needs to share this input:
a) its an "active" sensor and outputs whatever the supply voltage is (works on 5v and 12V - even up to 24VDC) when not triggered and goes to 0v when triggered. Tested an works as an active probe in PathPilot.
b) its from China so no returning it for a different configuration

Was trying to figure out how to invert / switch one of the signals, but the thought just struck me now as I type this out:

Can I wire the new touch probe in series with the tool setter and effectively make the toolsetter active? The difference is that the output is just open when the toolsetter triggers as opposed to being pulled to ground...

Otherwise I need to get back to figuring out how to easily, cheaply combine these 2 signals - I could unplug one and plug in the other but that requires changing the settings in PathPilot and I know me - I'll screw it up sooner rather than later.

 

[whydontu]

Active sensor has three wires? If so, simple mod to add a relay to output the appropriate signal to be the same as your existing NC tool setter, then wire the relay output and tool setter in series. What’s the part number of the active sensor? What is your supply voltage? Get me that and I can sketch up the wiring and give you a relay part number.

 

[Mike R]

The active sensor is one of these inexpensive ones: https://www.aliexpress.com/item/1005007768594340.html?spm=a2g0o.order_list.order_list_main.29.56141802OTCbnD

wiring diagram of it (three-wire system NPN-NO) and the input on the Tormach (31039 DIN) attached, along with the NC toolsetter.
I also have arduino type relay modules but thought a mechanical relay would be too slow for a probe...

I was just getting to the idea of a relay, or more specifically one of the PC817 opto - isolator thingies (I have these PC817 isolator ).
Connect between 5V and input on the switched side and have the probe and toolsetter in series on the input side?
Heres my sketch:

 

[whydontu]

Fairly simple solution. The probe output is <Hi> until it’s triggered. Feed the probe output to the base of a medium power NPN transistor, TIP31 or similar. As long as the out put is Hi, the transistor is conducting. Run the tool setter in series with the transistor collector, emitter to ground. If either the probe or the tool setter is triggered pin 5 goes high and does what it’s supposed to do

Switches in nanoseconds, the probe will be the device limiting the response speed.

I have drawn the probe as a simple switch, I didn’t show the probe third wire to ground.

 

[Mike R]

Thank you, proof of concept is wired up using a 2N3904 as that is what I could lay hands on in my pile of junk, and it works like a charm. Now I just need to make it clean looking and robust and I'll be done.

 

[Mike R]

One thing about this configuration is that it is now dependent on the probe to be in the circuit. Not a big deal usually but something to remember as the probe has a USB C type connector on it and I can see myself not connecting it before going to probe a tool length. I have been training myself to check that the tool setter works every time before I send the machine driving the head towards the table. One more reason to do so every time.
I just need to make a little holder for the probe that sits off to the side of the control cabinet so it can be plugged in but out of the way when not needed.

 

[whydontu]

Try throwing a 50k ~ 100k resistor between collector and base. This should trigger the transistor whenever the probe is disconnected, but probably not be enough bias to offset the probe output when the probe output is triggered and goes to ground.