3 wire proximity switch help

[cropwell]

Yes, each BoB input has to have its own resistor. The resistor pulls up the input to 5v (logic 'high') as its' normal state. When triggered the proximity switch pulls the input to 0v (logic low), so Mach3 has to see the input as 'active low'. Without the resistor you have a 'floating' input and the voltage on it could be anywhere, so it would not be predictable or reliable, and probably not work at all.

It is possible to configure switches as groups, but unless I was struggling for input pins, I wouldn't go there unless I had to.

Cheers,

Rob-T

[JAZZCNC]

Now I'm trying to connect them in a junction box and the Y+ will trip but the Y- won't when there conected together.

If those switches are traveling with the gantry then you only need one switch. Just put targets at each end to trip the switch.
Then Set Y++ and Y-- input to the same pin number.!

[mikem]

JAZZCNC

I read what your saying as use two switches but conect them to the same input pin on the BOB like cropwell sugestead. Is that what your saying?

[cropwell]

Hi

JAZZ and I are saying different things.

JAZZ says that the two ends of travel actually only need one switch, but with a trigger point at each end. in the Mach3 config screen the ++ and -- inputs for that axis will have the same pin settings. Mach3 knows which direction it is travelling so it will recognise as ++ or -- accordingly.

What I am saying is that if you are using two switches it is a simpler practice to use two inputs on the BoB. Each input pin needs a pull-up resistor.

Here is a useful document - if you can't see it PM me with your email address and I will send it to you.

Cheers,

Rob

[JAZZCNC]

JAZZCNC

I read what your saying as use two switches but conect them to the same input pin on the BOB like cropwell sugestead. Is that what your saying?

No I'm saying just use One switch. These switches sense a metal object for the trigger so just place trigger at each end using only one switch and one input.
Then set the limit Inputs for both ends to the same pin number. Mach doesn't care or even Know which switch tripped it just watches the designated input.

You can even Share the same Switch and one end trigger for Home function if you like by just setting Mach Home input for that axis to same pin number. Then turn off the Home SW option in General config so turns off Limits while it's homing and you don't get a limit trip. After homing Mach turns limits back on so your safe again.

Doing this means you only need 3 inputs for all axis including homing.

Edit: Doh didn't see Rob beat me to reply.

[mikem]

Jazz

That's exactly what I'm trying to do us 3 imputs for all axis. If I just use one swithh for the Y axis the switch is facing one way and picks up the metal object. What is going to trigger it going the other way if the switch isn't going to come in contact with the metal stop? How do I get to trigger it going the other way?
Mike

[Neale]

Make the switch point down, not sideways, and set the trigger pieces of metal just below it at each end of travel. It sounds as if this wouldn't give such accurate results but Jazz did some experiments a little while ago that showed this to work well.

[mikem]

Ok thanks make a lot of sence that way. I'll try it and see how it works.

Thanks Again

[JAZZCNC]

Make the switch point down, not sideways, and set the trigger pieces of metal just below it at each end of travel. It sounds as if this wouldn't give such accurate results but Jazz did some experiments a little while ago that showed this to work well.

Yes sorry I didn't look closely at the way you had the switches pointed. Neal is correct it does work very well I use the round type switch like this all the time.
Also saves the switches getting smashed by riding over the target rather than into end stops.

Keep the sensing distance small has possible for best accurecy.

[mikem]

So why I got you I have another question. When I hook up on switch to the 5V on the BOB and to the imput lets say on the y it works.Then when I hook up the X and add another transistor to the 5v neither will work. just when it's a single resistor on the 5v do they work as soom as I add another nothing works.

Any thoughts?