Need help with Homing for XYYZ (Resolved)

Hello expert,

I just completed my build and everything seems to work correctly using MESA 7i96s except for one last issue and I need your help, PLEASE!

I was able to home X,Z without any issues.  My Y axis has Y1 and Y2 (tandem) and they both have physical limit switches.  When homing my Y1, it stops and reverts a few millimeters before it hits the limit switch, but when Y2 senses the limit switch and it continues to travel forward and SLAMS into the switch.  Attached is my .ini and .hal file plus some screenshoots.  Please point me to the right direction. 

Thank you.






 

Can you confirm the home switches on y2 actually are detected in linuxcnc using halmeter?

Yes, but not via halmeter. it works when tap the switch manually twice. Also, I can see the led lit up on 7i96s board. I have not used the Hal meter but will try. Thank you so much.

If you have confirmed in halshow or halmeter that all the home switches are working and flow through to the joint home inputs, it's usually that one of the homing velocities is set to the wrong direction. 
I would edit your ini  file so all the homing velocities are really slow and try homing again. That will let you observe what is going wrong..
Then change the sign of the offending side.

What can happen if I am right is one side backs off the home switch but the other side goes the wrong way and cotinues on blindly so it never finds the signal edge.

Thank you, Cmorley and Rodw. I confirmed the halmeter signal (used for the first time, really cool) and your post gave me some ideas. it works now. I changed the limit switch setting on the Y2 from "Y2 Tandem home" to "Y2 Maximum Limit" then manually adjust the limit sensor positive for squareness. I hope this is correct way as LinuxCNC design unless you think otherwise.

Sorry, I take it back the limit just stop but not home. I will continue looking.

Thanks, which parameter is for homing velocity?

this is the velocity to find the home switch
HOME_SEARCH_VEL = -1.000000

this is the velocity used for actual homing after the home switch is found
HOME_LATCH_VEL = -0.500000

There is also
HOME_FINAL_VELOCITY = 0
This moves the machine from the hime switch to whatever is set in HOME_OFFSET
0 means it will travel at max machine speed, so setting this to a lower speed is good, for me usually 10.

Thank you for all the suggestions, I tried different value but no effect. not sure what I did but now Y continue moving forward while Y2 back off then stop after reset all the values.

To recap I have the following settings:

TB1/TB2 function:

0 X Axis StepGen
1 Y Axis StepGen
2 Y2 Tandem StepGen
3 Z Axis StepGen

TB3 :
0 unused
1 X Home
2 Y Home
3 Y2 Tandem Home
4 Z Home


Homing Behavior Sequence:

1. Z move + (up) hit the limit ,backoff then stop (good)
2. X move - (left) hit the limit backoff then stop. (good)
3. Both Y and Y2 moving - (forward to front)
- Both Y and Y2 hit the limit almost at the same time.
- Y2 backoff then stop
- Y continue moving forward, I have to hit the toggle machine power off button.

Here is my setting for both Y and Y2

HOME_OFFSET = 10.000000
HOME_SEARCH_VEL = -1.000000
HOME_LATCH_VEL = -0.500000
HOME_FINAL_VEL = 0.000000

I confirmed both

hm2_7i96s.0.gpio.002.in (Y)
hm2_7i96s.0.gpio.003.in  (Y2)

TRUE when touching their limit switches.

Thanks again for the helps, I can't wait for it to run .