Homing with ClearPath Servo's hard stop

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Homing with ClearPath Servo's hard stop

Postby chjade84 » Wed Sep 26, 2018 6:38 pm

I wanted to give the ClearPath hard stop homing method a try since it's supposed to be quite accurate and my homing switches aren't. I was wondering if you knew how I may accomplish this since the motors don't give any real "feedback" as far as I can tell once they've homed - or a real way to tell them to home. From what I understand, my best option would be to have them home automatically on the first enable after the software starts. That's easy to set up. The harder part is to have the software set the axis home locations since it won't use its homing routine and won't get feedback from a sensor saying it's been reached. Any idea? Page 103 in the manual here: https://www.teknic.com/files/downloads/ ... manual.pdf

Thanks!
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Re: Homing with ClearPath Servo's hard stop

Postby spumco » Sun Sep 30, 2018 3:32 am

I read the manual after you posted this and couldn't figure an easy way for the HLFB signal to communicate to your controller. Was hoping somone else had an idea so I didn't bother posting "I don't know either."

I think it's time for you to call Clearpath as they may have an idea - at least getting you in the ballpark so you can integrate what they tell you with UCCNC. The only thing - admittedly vague - I could come up with is this:

- HOME ALL button tied to user-written macro which enables each drive sequentially.
- servo 1 enabled, which starts the auto homing sequence, reaches home, sends HLFB ASG-Position signal.
- macro registers ASG-position signal and writes "homed" to axis in UCCNC, then
- enables servo 2 and lather, rinse, repeat.

The HLFB ASG-Position pins are not set in UCCNC as 'limit' or 'homing' pins, just general inputs. I don't think you can use the pin later for other functions (like Servo On) as that would require direct programming via PC to switch the HLFB mode.

So the queston to ask Clearpath (Teknics) is - what, if any, HLFB signal is used by the motor when auto homing is complete?

Let us know what you find out...

-Ralph
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Re: Homing with ClearPath Servo's hard stop

Postby spumco » Sun Sep 30, 2018 11:30 pm

Vmax549 wrote:It should be easy enough to set UCCNC Machine coords from code once you have reached Axis home with the drive.

Same if you used ABS encoders. The encoder talks with UCCNC and tells it where it is at and UCCNC resets teh machine coords to the abs values.

Just a thought, (;-) TP

(;-) TP


Terry,

The Clearpath servos don't have encoder outputs. That's one of the features they left out to cut down cost. All it has is a "High Level Feedback" (HLFB) switch you can program to respond to various conditions. That was kind of the general/vague idea I suggested - use the HLFB switch to trigger an I/O pin, and have a macro in UCCNC recognize the pin as a 'homed' signal.

And this is one of the reasons I quit thinking about Clearpath servos for my mill. Other stuff, maybe. But not for my mill.

-Ralph
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Re: Homing with ClearPath Servo's hard stop

Postby Regulator » Tue Oct 02, 2018 12:11 am

Eagerly watching where this thread goes....lol, as I'm a clearpath user but didn't think there was a possible way to make hard stops work.
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Re: Homing with ClearPath Servo's hard stop

Postby ThreeDJ16 » Thu Oct 25, 2018 10:25 pm

I know this thread is a month old, but isn't the ClearPaths signal out a fault signal, therefore needing a power down after it occurs? A couple of friends are using the bump stop method, then just manually zero their program and reset power on the Clearpaths. Personally think that is a crappy way to have to run them. You would think that the makers of Clearpath would incorporate an easier homing method by adding one more signal out besides a fault.

It's also one of the reasons I've been looking at DMM servos for my axis setup, as they have a zero pulse output along with a fault output. So you zero to a normal switch, then back off to the zero pulse. So it takes 1 homing input for all 3 axis, then 1 additional homing input for each axis to do this and also requires a special homing macro. I did this on my Emco lathe with closed loop steppers and a hall effect sensor on each ball screw pulley. Works out very accurate.

-=J
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Re: Homing with ClearPath Servo's hard stop

Postby 1JUMPER10 » Sun Nov 25, 2018 3:55 pm

chjade84 wrote:I wanted to give the ClearPath hard stop homing method a try since it's supposed to be quite accurate and my homing switches aren't. I was wondering if you knew how I may accomplish this since the motors don't give any real "feedback" as far as I can tell once they've homed - or a real way to tell them to home. From what I understand, my best option would be to have them home automatically on the first enable after the software starts. That's easy to set up. The harder part is to have the software set the axis home locations since it won't use its homing routine and won't get feedback from a sensor saying it's been reached. Any idea? Page 103 in the manual here: https://www.teknic.com/files/downloads/ ... manual.pdf

Thanks!


Set up your hard stops so that they stop the gantry (or axis) at a square position. I set my CP's to hardstop home on power up but as you state, they can also be set to home on first enable. The servos will home to the hard stop then back off the distance you specify in their firmware. For example, your hard stops are at the Y0 end of your axis travel. For most machines (well, mine anyway) this is the front. The servos travel until they contact the hard stop then back off 1" (or what ever number of counts specified in firmware). Your gantry is now square and stopped in its home position. To set this position as the home position just click the "Y" axis home button in UCCNC (assuming you don't have any home switches enabled!). That's it. Your axis is squared and homed.
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