Homing SW Function/Operation

[Mr.Chips]

This is how I think 3 axis homing works. Is it correct?

Let's say that the X Y Home switches are located in the left rear position and 1/4" away from the Limit switches. And the Z axis homing switch is located 1/4 below the upper Z axis Limit switch.

When the Home button is pushed the Z axis is moved first up to it's Home position, then the other two steppers are activated and the router is moved to the left rear direction until their Home switches are activated.
Is this sequence correct? Z moves first?


In the situation where you have hit the left rear limit switch, you couldn't press the Home button because the machine would want to drive it to the left rear, its normal home drive direction. This raises two questions.

1. Does Mach 3 know it location, and would drive Home safely, even when activating the left rear Limit switchs?

2. Or would you have to Jog it past the Home switches then hit the Home button?

Thanks for the patience in reading this long draw out question.

Hager

[ger21]

Not sure if I understand you, but the limits should be after the home, at the end of your travel. But once you pass the home switch, you'll have to manually jog back to the other side of the switch before homing again. Mach knows which direction to home, but doesn't know where the switch is. Does that make sense. Many people use the home switch as the limit switch. That would alleviate the problem I just mentioned.

[Mr.Chips]

Originally Posted by ger21 Not sure if I understand you, but the limits should be after the home, at the end of your travel. But once you pass the home switch, you'll have to manually jog back to the other side of the switch before homing again. Mach knows which direction to home, but doesn't know where the switch is. Does that make sense. Many people use the home switch as the limit switch. That would alleviate the problem I just mentioned.

So, I need 6 separately wired switches, two on each axis. One of the two on each axis would be defined as a Limit and also a Home switch. Is this correct?

If this is the case I don’t have enough connections on my board, it only supports three switches. In this case I need to add a second parallel port and buy another breakout board. Is this the only solution?

Thanks
Hager

[ger21]

Originally Posted by Mr.Chips So, I need 6 separately wired switches, two on each axis. One of the two on each axis would be defined as a Limit and also a Home switch. Is this correct?

Yes.

Originally Posted by Mr.Chips If this is the case I don’t have enough connections on my board, it only supports three switches. In this case I need to add a second parallel port and buy another breakout board. Is this the only solution? Thanks Hager

I answered in your other thread, but I need more info on your breakout board.

[Mr.Chips]

The section dealing with limit and home switches is JP3. center right side of the drawing. This is a different board that I currently have but is Optic isolated and current one isn't, but both have the same number of limit/home
sw connections.

To me it looks like there is just two limit sw connections and one home. This would only support three switches Correct?
Thanks
Hager

[ger21]

I think you can use pins 10 and 11 as well for limits and home. At least 1 of them.

[Mr.Chips]

Originally Posted by ger21 I think you can use pins 10 and 11 as well for limits and home. At least 1 of them.

Don't give up yet Gerry. I havent. He He

Will this work???? I need 4 connections for this, there are three on the breakout board and if I could use 10 or 11 as you stated, I would have enough lines for this configuration. Does it matter which one I use???

In the below drawing I show all six limit switches for the three axis. Red for Home and Limit and Blue for limit.

In order to implement this there will need to be four limit connections, they are explained below.

Three switches (shown in RED) have been selected to act as both Limit and Home switches and each has their own separate line so that Mach 3 can tell them apart.

Three switches (shown in BLUE) are connected to all three axis in a common serial line and will act as Limit switches.

Please review the drawing and either confirm that this layout will work or that it won’t.

Thanks
Hager

[ger21]

Yes, that should work. Look in the Mach3 ports and pins input page, it should show you what pins you can use as inputs.

[Mr.Chips]

Originally Posted by ger21 Yes, that should work. Look in the Mach3 ports and pins input page, it should show you what pins you can use as inputs.

Thanks Gerry,

Thanks to you, I now have a Limit and Home switch design that I can have confidence in connecting up.

Hager