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Hi everyone.
Ưhile working with linuxcnc ethercat, I have some questions, hope to receive advice or comments from everyone.

1. Normally, we often use limit switches to determine "home position". 

2. My idea is to use the servo motor position in "absolute mode" as "home position". That means, for example, in the xyz robot, I mark a fixed point on each axis, then move the axes to that point (this point will be the "home position"). Next, I read the absolute encoder values ​​from the ethercat servo command on the 3 axes, and get the value of "home position". So how can I implement the above idea?
Thank you very much.

Please feel free to correct me if I have gotten anything wrong here. This post is for future me, and whomever else may benefit from it. I will likely edit this if there are corrections.

I put together a circuit on a breadboard, for testing. I still have to set this all up in LinuxCNC, but at least I have a physical thing to work with. The white wire is GND, orange is switch position 1, blue 2, green 3, & red 4. I will use this for selecting axes: Off, X, Y, Z, and a similar thing on another switch to select x1, x0.1, x0.01, x0.001, although microns are probably a pipe dream on this machine.

Orange (1) has no conductivity to bit 0 or bit 1; 0:0
Blue (2) has conductivity to bit 0 and bit 1; 1:1
Green (3) has no conductivity to bit 0, but does to bit 1; 0:1
Red (4) has conductivity to bit 0, but not bit 1; 1:0

Now I have to figure out Mux8 for a mode switch. That's eight inputs for three rotary switches, so that leaves eight inputs left on P2, of which two are going to an MPG. Plus all of the P1 inputs.

The thing that updates every millisecond is CommandedPosition, linuxcnc calculates a new position value every millisecond which goes to the MCU on the card. How many steps does the step generator need to make to go to that new position?
There is the scaling parameter 320 steps/mm. Say it needs to go 0.1 mm in one millisecond which is awfully fast but just an example. 0.1 *320 = 32 steps to make during that millisecond.
Another way could be to calculate number of steps to move in hal, in linuxcnc. It is not done that way. The new position, commanded positition, in machine units, is fed to the stepper driver, be it Ethercat, parallel port or Mesa card.
If you change the microstep setting on the driver itself you need to change stepspermm accordingly.

 

Hi,

Firstly just want to state, Probe-Basic looks fantastic. Credit to you guys. Way over my head, but looking forwards to getting is working.

I am slowly going through the process of building up a CNC from a mill and started my journey on Gmoccapy. I have MESA 7i96S, 7i85S and a 7i73. It took me quite a while to get it configured to run and now making progress, however, I feel Probe-Basic is on the charge and wanted to shift across to this.

I will be using xyz at this point. Have installed Debian from the Linux install iso.

My question as a newby, is what is the best approach to move across and make sure that the config that I have been able to develop is retained at east in a way that can be realistically used to help configure Probe Basic. I am happy to blow away the environment and recommence, just don't want to loos e something that can help resolve a future problem from a current working solution. What is the best approach to this.

NOTE: I did try to just process through he install, but errors occurred in the get apt code so I stopped there. I think it may be to do with root security.

I still don't understand, what do I use the lcec.0.D1.stepspermm pins for?

Do you have
home_sequence = -2
for both Y joints set in the ini file?
Or -1 or -3....

I'm not sure how MesaCT determines card resources.

Is this PWM setup for interfacing with PWM motor drives
and using encoder feedback?

If so, a 7I97T configuration would be close
(with perhaps some PWM frequency/mode changes)
 

I'm running the LinuxCNC OS provided on the LinuxCNC Downloads page:  Downloads

• LinuxCNC 2.9.2  Raspberry Pi 5 OS based on Debian Bookworm  Raspberry Pi 5 Uspace compatible with Mesa Ethernet boards. Note that SPI is not currently supported with the Pi5.

I used rpi-imager to burn the OS onto the micro SD card for my Raspberry Pi 5.  So far the OS is working fine.  I just can't get probe basic to install.

yes but why? when i try ref all... it works fine...
i think probe basic ref y do only ref my y1 axis and not my y2...
i have 2 homing sensors for y

Thanks for the feedback. Any tips on creating a pin file for the 7i95t firmware you sent to use in mesaCT?

I wanted to make my own user tab for them. But I’m unclear how to do that, and I’m unsure whether you can use a user tab well while the machine is running in auto. I haven’t tried yet.
I was going to add them to the user buttons. But I’ve used up most of them at this point.
Down the road, I also want to learn some other things. I’m adding pneumatics to my CNC to run some hold-downs, as well as an air blast.
I had the idea to add a pressure gauge to the system so I could set the machine to pause if there was a loss in air pressure, assuming that would cause me to lose a hold-down.

I have a PrintNC CNC router with ER20 manual collet in the spindle. Work area 1200x600x100. I have a tool setter built into the table so the plate is something like 1mm under the table. The position is X1050 Y70. Why is it like that? Because it doesn't get in the way of big slabs that i can left hanging out of the work area.
I can lower the spindle, but it is still more than 100mm above the tool setter, so I cannot 'touch' it like the settings in PB says (that is if I understood it correctly)

I use the free version of Fusion360 and do jobs like making casting molds out of blocks of polyurethane and some small woodworking projects. So small jobs, handful of tools to change. But I need precision and automation. And that's why I need to manually change the tool (because of poor man's manualspindle), but do the measuring of the offset automatically.

My procedure:

1. I have multiple per-operation files of the job or one big file (free Fusion360 doesn't allow that and I'm experimenting with github.com/TimPaterson/Fusion360-Batch-Post)

2. I fasten the stock to the table, put a pointy rod into spindle and set the WCS origin. Or put the first tool of the first operation and do the setting of origin that way - it's precise enough and I don't have to switch tools unnecessarily.

3. Then I start the program. When it runs into tool change it should go as:

3A. move the Z all the way up
3B. move to defined position where is easy for me to change the tool
3C. wait until I change the tool and click on a button
3D. move above the tool setter
3E. move relatively fast to some Z
3F. move slowly until touch of or error
3G. move up a little bit
3H. move extra slow until touch
3I. <do some magic tool offset sh*t so the tip of the tool in G54 Z is the same as previous tool>
3I. move Z all the way up
3J. continue with the job

So far the subroutine tool_touch_off.ngc does most of it or I modified it to behave like that. What was missing is the moving to known location and what I think is an error - that it doesn't set the new tool number. It stays the same. I added the M6 command so it shows the dialog waiting for change. I lavishly stole that from here: wiki.printnc.info/en/controllers/linuxcnc/tool-setter-no-probe

But it still doesn't work the way I need to. Both of these routines. Fusion360 is messing with G43 in a way I don't understand why - it does "G43 Z15. H0" after each tool change, which messes with the macro above and the fix is "remove that from postprocessor" which is a big no-no for me.

I like very much the idea of tool_touch_off.ngc. Especially the way it get's its absolute position by using a relative position but at known absolute Z height. Very clever! But from a quick test the new tool after change ended up again in wrong Z height.

I am determined to make it work because it is imperative to my work. But it sure as hell ain't walk in the cake. Or piece of park for that matter.