Homing problem in mach2

[atifeh]

Hello

I am trying to set my machine with the trial version of mach2. I have arranged 5 limit switches, NC, daisy chained on pin 11 and 3 home switches, NC, on pins 12, 13 and 15. All correctly defined in the ports and pins config. I have also set the soft limits which work fine. The limit switches work fine too. My problem is:

When I click the RefX button on the offset screen the X axis moves slowly until it hits the switch, this also happens when I press the home button or alt-H. In Diag. screen the X lamp goes off. But when I click on the refY and refZ buttons, they only travel a minute distance and in the opposite direction of the switches. Each time I click the RefY and RefZ button, it travels the same distance and in the wrong direction. I reversed the axes direction movements but the problem exists.

The switches work fine since when I manually switch them off, their respective lamp goes off on the Diag. screen, which means the wiring should be right. There is a flaw though, I have noticed that Y and Z home lamps flicker sometimes in the Diag. screen which I suspect this might be the reason for the fault. Please help me with this. Where did I go wrong?

Thanks
Nader

[ger21]

HAvent used Mach2 in a long time, but try increasing the switch debounce to 2000, or maybe up to 5000 even to see if the flicker goes away. I think there is a homing screen with a checkbox for home negative?

[atifeh]

Thanks for the help,
I changed the debounce and now the RefY and RefZ buttons are responding. Yet another problem:

The axes are seeking the home switches in the opposite direction. I reversed the motor directions, they went in the right direction towards the home switches but then all my co-ordinates went negative, i.e. on G0 X1 they hit the limits instead of moving forward. How should I fix this?

You mentioned about changing the signs of the switches. The only place I could find it, was in the ports and pins screen, but it has said this should be used when home and limits are shared. Is it what you referred to? Does it change the seeking method of Mach?

Nader

[Torchhead]

There is a setting in Homing/Limits for the direction the table moves to find home and also the homing speed and the distance value it starts at.

As Ger21 said, switch bounce on homing can cause all kinds of problems. The software only wants one home signal per ref and switch bounce confuses it and makes it start moving in the opposite direction.

If you have isolation coming from the switches to the port it will cut down on a lot of the noise but the switch bounce is a mechanical thing in the switch that only can be cured by increasing the setting mentioned.

[atifeh]

Gerry, Torchhead, thanks a lot for your help. My problem has been solved.

Thanks again,
Nader

[MANUELLE]

Hi everyone:
when I homing the XYZ axis on mach3 sometimes after touch the switch stops right there and not returner to be ready and sometime works properly sometimes on Z home sometimes on X home sometimes Y home axis.
switches are hook up this way Port pin then switch then Case ground can some one can help me, Thanks

[Torchhead]

1. Read other posts above. Problem is switch bounce. Set Input Debounce value higher in MACH3.

2. Without ground isolation between your table and PC noise can be conducted. The Home and limit switchs need to have an isolated ground (separate power supply) and opto inputs to eliminate the problem.

[MANUELLE]

Thanks,I set the debounce interval to 1000 and left the index Debounce 0
so far is working fine,again,thank you.