Using a combination of mechanical limits and proximity

[TCandee]

I currently have a 3 axis mill with mechanical home switches on a “home all” input and software travel limits. I am adding a fourth axis and it has a built in proximity home sensor. Is it possible to leave the first 3 axis the way they are and add the 4th proximity home to another input? I don’t think the proximity can be wired in series with the mechanical on the other 3 axis.

It only has a 12v input (possibly 24v, signal and a common.

[Black Forest]

I use proximity switches on machines that can be wired normally closed or normally open.

[Dave_C]

currently have a 3 axis mill with mechanical home switches on a “home all” input and software travel limits.

I don't think you can do that because "Home All" means ALL! Not just three of the four.

"Home All" is a strategy that uses a closed loop of all the limit switches. While homing it breaks the loop by homing {tripping} the axis limit that is moving, sets that axis to home and then moves on to the next axis. Each time it moves on to the next axis to home it is still looking at the same "home all" input to open as the next axis arrives and trips its switch.

If you can use the prox switch to run a NC relay, then you could add that relay to your loop and then the home all strategy will work.

Dave C.

[Gary Campbell]

I am adding a fourth axis and it has a built in proximity home sensor. Is it possible to leave the first 3 axis the way they are and add the 4th proximity home to another input?

Sure, I do it all the time. I have used 2 versions: 1) where I have the power to the sensor on a relay that is powered only during homing and the appropriate code is added to the cncm.hom file 2) Where the 4th axis homing code is added to a macro button and is only homed when needed

[Dave_C]

I am adding a fourth axis and it has a built in proximity home sensor. Is it possible to leave the first 3 axis the way they are and add the 4th proximity home to another input?

Sure, I do it all the time. I have used 2 versions: 1) where I have the power to the sensor on a relay that is powered only during homing and the appropriate code is added to the cncm.hom file 2) Where the 4th axis homing code is added to a macro button and is only homed when needed

What I was focusing on was the OP's question of putting the Prox switch on another input and wondering if it would work without customization. If he was at the level of being able to implement Gary's two ways I don't think he would have needed to ask if it could be done.

There are many levels of tech skills on this DIY site and it is hard to know how to answer a question without either being too technical or not being technical enough.

Dave C.

[Muzzer]

If the existing 3 switches are normally closed and are set up to pull the Home All input down to ground when things are good, then surely it is a simple matter to connect the "bottom" of the switch chain to the open collector of the proximity sensor. If the sensor goes high impedance or any of the switches go open circuit, the input will go high. Isn't that what you'd want here? You'd need a normally closed proximity switch - the Omron ones I use are available in both NO and NC.

Perhaps I'm missing something?

[TCandee]

Thank you all for your insight. You are correct in assuming I may not be at the level to implement some of the more advanced methods. I struggle with plc programming etc. But it helps to hear them and investigate the possibilities. The relay option and adding it to the current home all circuit seems the best route for me.

I hadn’t thought about the times when I am not using the 4th axis. I assume, and will investigate, that I can just use 2 different setups in the Wizard and choose the one I will be using before running any code.