Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: inivator on June 15, 2008, 04:29:54 PM
-
I'm building a gantry type small router. Is there any wiring diagrams for simple xyz limits and homing switches.
Inivator ???
-
Dont really need a wiring diagram, all you need are normally closed switches and run them all in series, ie have a wire from an Input pin of the parallel port(or breakout board) run this to one wire of first switch, other wire of first switch goes to one wire on second switch, other wire on second goes to third switch and so on until all your switches are connected then the last wire goes to a ground on your port (or breakout)
Doing it that way will mean you only use one pin of the parallel port for all limits and Home switches. If you prefer to have each axis seperate then you can wire all the switches on each axis in series and use one Input pin for each axis.
Hood
-
Dont really need a wiring diagram, all you need are normally closed switches and run them all in series, ie have a wire from an Input pin of the parallel port(or breakout board) run this to one wire of first switch, other wire of first switch goes to one wire on second switch, other wire on second goes to third switch and so on until all your switches are connected then the last wire goes to a ground on your port (or breakout)
Doing it that way will mean you only use one pin of the parallel port for all limits and Home switches. If you prefer to have each axis seperate then you can wire all the switches on each axis in series and use one Input pin for each axis.
Hood
What about pullup resistors?
Monte
-
You do not need any if you have a "dead" breakout board, because the LPT1 port has built in pull-up resistors.
You may need one at the "pin" end of your breakout board - depending on how it is configured - you will have to read up on it.
The idea is the pin is normally +5v. The path through the series of switches to earth holds it at 0v until one of them (and as Hood said - you can have as many as you like) opens, and cuts the 0v path. The pin should then go to +5v to give a signal to the computer.
Some breakout boards have isolators on them, and the pin out voltages are reversed i.e. where they are normally held to 5 volts (from the computer) they are at 0volts on the breakout board. If this is the case you can either use a pull up resistor to pull it up if a switch is activated - or instead of the last switch being connected to 0v, connect it to 5 volts - so that the idea of the series path is the same, but just operating in reverse - normally held at 5 volts, when the series is broken it drops to 0
Mach 3 can cater for both systems.
-
Understand the wiring now, but how is the configuration in the Mach3 software setup?
Inivator
-
If you have all limits connected in series and using one input then you just asign that input for every axis, ie if you have X+,X-,Y+,Y-,Z+Z- all connected in series and going in to pin 12 then you set them all to pin 12. Same for the Homing switches, you can actually use a limit switch as a home switch, Mach will only see it as a home switch when you have told Mach to Home, all other times it will be treated as a limit switch.
Hood
-
Thanks...Sounds simple, very similiar to my mind...........
Inivator
-
Thanks...Sounds simple, very similiar to my mind...........
Inivator
You are in good company then :)
Hood
-
Hood;
When you're ready to take a vacation, come to TEXAS, and I will show you how red-necks live.................I've been here 70 years, and have just about figured it out, whatever it is............
Inivator
-
:D
-
I thought I would tag my question onto the bottom of this old post as it seemed pretty appropriate.
On page 4-8 of the Mach3 users guide there is a diagram for wiring the limit switches. What I don't understand though is what the 5volt supply does. I have tried taking a +5 volt from a USB and feeding it via a 470ohm resistor but it doesn't work. I then read the mail below and that suggests that the PC has its own +5v supply from the parallel pin port (PPP) and that the PPP has its own built in resistor, though that seems to contradict what is written by Art & John Prentice on page 4-9; "Note that for relaible operation you need to "pull up" the input to the parallel port. As mechanical switches can carry a significant current a value of 470R is shown which gives a current of about 10 milliamps."
I have run a simple loop from a PPP input via my machines proximity switches back to PPP 0volt and that seems to work fine so I guess that what is written on this earlier thread is true, but I can't ignore what is written in the manual.
Clarification would be appreciated
Thanks ...Sweep