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Help Configuring Limit and Homing Switches
« on: October 23, 2007, 01:40:08 AM »
My 1st Posting!

I am confused about settingup my limit and Homing switches.  As you can see in the below drawing each axis has two normally closed switches, one just a limit and the other is both a limit and home switch both switches are wired in series.  The breakout board manufacture showed this thpe of switch configuration and I understand that this is possible, I just can't find the way to set it up.  The X axis is connected to pin 10 on the breakout board.  Mach3 must have a way of knowing the direction it is travling and if it hits a limit or a limit and home switch. The breakout board has Gnd, 10, 11, 12, 13, and 15 for the limits, home and EStop switches.
 How do you configure this?  Also If a limit is hit I want to drive off of it automatically, to get out of theh error condition.
I also pasted a the input screen where I think this is done, but don't know how.  Please refer to tabs and screens in their exact names, so I can see how to do the setup.  Remember this is my first post.
Mr. Chips
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Re: Help Configuring Limit and Homing Switches
« Reply #1 on: October 23, 2007, 03:54:35 AM »
I am confused about settingup my limit and Homing switches. As you can see in the below drawing each axis has two normally closed switches, one just a limit and the other is both a limit and home switch both switches are wired in series. The breakout board manufacture showed this thpe of switch configuration and I understand that this is possible, I just can't find the way to set it up. The X axis is connected to pin 10 on the breakout board. Mach3 must have a way of knowing the direction it is travling and if it hits a limit or a limit and home switch. The breakout board has Gnd, 10, 11, 12, 13, and 15 for the limits, home and EStop switches.
 How do you configure this? Also If a limit is hit I want to drive off of it automatically, to get out of theh error condition.
I also pasted a the input screen where I think this is done, but don't know how. Please refer to tabs and screens in their exact names, so I can see how to do the setup. Remember this is my first post.

Hi - Your config for your switch setup looks fine as long as you are actually on port 1 and you do have it wired as you say 10,11,12 and common sig gnd. What is not working?

Home function: Mach does indeed know which way it's travelling and therefore when it hits a switch it decelerates, stops and then backs off until the switch is made again. That's home.

Limit function: Mach doesn't care which way it's travelling - any limit switch going open will immediately result in a dead stop. You then have to JOG off the switch. It's not really logical to want this to happen automatically - a limit is an error - it shouldn't happen - it's Machs way of telling you it's gone out of bounds and needs manual (thoughtful) intervention. Suppose for example it hit limit because it has lost steps - it doesn't know where it is - how can it then automatically sort itself out?

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Re: Help Configuring Limit and Homing Switches
« Reply #2 on: October 23, 2007, 04:09:31 AM »
Hi, Mr.Chips

Your sw's are setup correct, you may need to set the "Active low's" from X to "Check" If seeing limit error all the time.

You may need to do the Same with the E-Stop also further down the window above, If it's flashing or not responding to the e-switch.

Also make sure the Emulated-es are X and not Checked.

There's a setting to change the Home Dir. It under Config, Home & Limits Page.

Yes Mach row's whether your homing or hitting  limit's and when it's working correct should move just off the switch.

In fact you can just use one pin and run all 6 sw's in seres if your not doing something special.

Let us now What else is going on.

Hope this Helps, Chip

Beaten to the post once again !!
« Last Edit: October 23, 2007, 04:16:35 AM by afn09556 »
Re: Help Configuring Limit and Homing Switches
« Reply #3 on: October 23, 2007, 09:55:13 AM »
I have some more information to add to aid in understanding my problem and what can be dont to correct it.

When jogging the Y Axis in the "-" direction, I hit the "-" direction limit switch with my hand (This will also be my Home SW.
As soon as I hit it the travle stops, and all three Leds (- + and home) are lit in the "Diagnostic screen".  I noted the "Y" direction as an example, all Axis act like this.

I must have touched some thing some where in Mach3 because I can now jog off the held SW and then I can press and clear the Reset light.

In the video I saw only the opened limit SWLED  light up.  This is what I would like to happen.

Also they talk about it automatically driving off the "Hit" SW automatically.  Would also like to have this happen if Mach3 will do it.

I did a quote, to get to add this additional information, but I don't see where to add an attachment.  Is it possible to add attachments in this situation?

Thanks

« Last Edit: October 23, 2007, 09:57:00 AM by Mr.Chips »
Mr. Chips
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Re: Help Configuring Limit and Homing Switches
« Reply #4 on: October 23, 2007, 11:57:22 AM »
When jogging the Y Axis in the "-" direction, I hit the "-" direction limit switch with my hand (This will also be my Home SW.
As soon as I hit it the travle stops, and all three Leds (- + and home) are lit in the "Diagnostic screen". I noted the "Y" direction as an example, all Axis act like this.
This is exactly as it should be. Remember you're sharing input pins.

I must have touched some thing some where in Mach3 because I can now jog off the held SW and then I can press and clear the Reset light.
probably auto limit override was what you touched.

In the video I saw only the opened limit SWLED  light up.  This is what I would like to happen.
Then you'll need either external logic or individual switches for limits and home i.e. 9 in all for a three axis machine where each switch is allocated it's own input. You'll therefore need to add a second parallel port.

Also they talk about it automatically driving off the "Hit" SW automatically.  Would also like to have this happen if Mach3 will do it.
Sorry can't help you here - are you sure you arn't confusing limits with home. I still think it's a bad idea to have anything happen automatically after a limit but that's just my opinion.

I did a quote, to get to add this additional information, but I don't see where to add an attachment.  Is it possible to add attachments in this situation?
see additional options to the bottom left of a standard reply.

Cheers

Ian
Re: Help Configuring Limit and Homing Switches
« Reply #5 on: October 23, 2007, 12:24:36 PM »
QUOTE
"Then you'll need either external logic or individual switches for limits and home i.e. 9 in all for a three axis machine where each switch is allocated it's own input. You'll therefore need to add a second parallel port."

What do you mean by "External Logic" could you explain how this would be used?

I am currently using a dedicated desktop PC for my CNC, and have added a PCI Parallel card to it as recommended by my Isolated breakout board Manufacture, to further protect the PC. 

If I add another PCI Parallel Card will I need another isolated breakout board, as the current BO board only has 5 connection points for home, limits and EStop?

Let me understand, in the Mach3 videos you say that their machine is set up with 9 separate switches?  I don't think this is the case because in their example of the "Input pins" it shows the + and - limit SW's connecting to pin 10, and the home connecting to pin 11, I might have 10 and 11 reversed, I'm working from memory here.  But when they manually press one SW only one LED lights, this makes me think that somewhere in Mach 3 you can define what switch is being hit by the direction of movement before hitting the SW. 

Sorry to keep beating this possibly dead horse but I want to understand and set my machine up properly and safely.

Mr Chips

Mr. Chips
Retired 3M'r