Thread: 3 wire proximity switch help
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.
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?
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.
The Following User Says Thank You to cropwell For This Useful Post:
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.
Last edited by JAZZCNC; 05-10-2015 at 09:35 PM.
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?
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.
The Following User Says Thank You to Neale For This Useful Post:
Ok thanks make a lot of sence that way. I'll try it and see how it works.
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.
Last edited by JAZZCNC; 05-10-2015 at 10:46 PM.
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.
FOR SALE: Proximity sensorsBy Web Goblin in forum Items For SaleReplies: 5Last Post: 13-09-2014, 07:02 AM
By Matt81 in forum General ElectronicsReplies: 9Last Post: 19-04-2014, 10:38 AM
By davrich in forum General ElectronicsReplies: 12Last Post: 17-01-2014, 07:00 PM
By Bruce in forum General ElectronicsReplies: 7Last Post: 13-01-2014, 06:21 PM
By kingcreaky in forum Resources & HelpReplies: 20Last Post: 23-10-2013, 12:30 PM