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I really don't know the answers here, but maybe some things you can try while you wait for someone smart to chime in...

Disconnect the encoder feedback and just use the stepgen position  - i.e. run it open loop.  Still choppy?

EDIT - nevermind, you already did that

Check the step-to-distance values.  Do you have really coarse steps per degree/rotation or something?  I'd start by:

• Figuring out the maximum input frequency of your drive
• Do some math
• Set the drive's internal steps-per-rotation to as high as possible without exceeding the max input freq at your maximum spindle speed
• Adjust INI & HAL files so the spindle and axis steps-per-whatever match your new drive parameter values
  
  I don't know if either of these will help, but they're free to test.

I indeed have all the axis stepgens in control_type=1, really all I changed from yours in spindle config are the step and encoder scaling pretty much.

That was sort of a weird for me that other axis work fine, but C axis has this choppy behaviour. Obviously it's the only one with actual feeedback but I tried looping back stepgen pos-fb instead of encoder feedbackk in the hal, which should in my head mirror the setup of x and z axis, however the choppiness still remained. Unless I'm missing something silly again

Hi All,

have an early 7c81 with I bought couple years ago to use with the PI4, but that system was to slow for my setup.

Now I like to replace my rater large PC with a PI5 setup, but I found out that I have to flash it with a PI4 to make it work.
Can I flash the 7C81 with a PI3 instated?
I tried but it doesn't seem to connect, the wiring is correct and SPI is enabled.

do I have to use a certain version of Mesaflash, I have 3.5.11 from the LinuxCNC image.

 

Keep in mind that we're reaching the limits of my competency...

I think the typical/standard configuration is to put the LCNC stepgen in velocity mode (stepgen.N.control-type = 1), and let LCNC's PID manage getting to the target position.

I seem to recall reading a forum post a while back describing where some developers discovered (years ago) that a velocity-mode stepgen w/PID wound up being more accurate - or otherwise 'better' - than a position-mode stepgen.

So instead of using stepgen.N.position-cmd as the PID output, stepgen.N.velocity-cmd is used.  Or something like that.

How are your other axes controlled?  Velocity-mode or position-mode stepgens?

Thank you for the clarification. What can I find the EtherCAT setup instruction? I only see an example for stepper drive. The reason I want to use API, because my system is not only doing CNC motion, but it may include other sequence. I am not familiar with LinuxCNC enough.

hilinda1 wrote:

I prefer to use API for my application. Please advise. Thank you guys.  


 

That is all good and dandy, but why?
LinuxCNC has several trajectory planners that you can switch between, so why add another layer between them?
Check the docs and GitHub, you can probably add another API there somewhere, so try the Run In Place version as you can change stuff and test quickly.

Todd wrote:

I believe you can use a switch, but the switch and the PCs ethernet port need to be dedicated only to this use. If you want to also have an ethernet network/internet connection you will need a second nic on the pc for that.

 

I have not tried that recently, but it has worked for me in the past. I had two Mesa cards connected to a switch, each with its own address.

When I tried connecting other devices to that switch, (modbus tcp, etc), that did not work. Those needed an additional NIC.

Some switches do not behave. I tried using a router instead of a switch one time, that did not work either.

LinuxCNC is a fully-fledged CNC controller.EtherCAT Cia402 is supported.I don’t think you can extract any parts for your purpose.It wouldn’t make any sense anyway.

I do not know, swap is a Linux thing, so should work.

I am currently controlling 3 EtherCAT servo drivers via SOEM. I want to run some G-code with my system. I am searching a G-code interpreter and trajectory planner in C++. Then I found LinuxCNC. I read some document and video. I have some questions below.

1. Are there G-code interpreter and trajectory planner API I can call for my application from LinuxCNC?
2. Is there a way to connect my EtherCAT servo to Linuxcnc?

I prefer to use API for my application. Please advise. Thank you guys.  

 

I updated to 2.9.8 and everything seems to work well now. Thank you !

The drive is an Astraada SRV-63. There's only analog in and serial for speed mode sadly.

However shouldn't the stepgen treat it like a velocity signal anyway? As in it generates signal until it reaches setpoint, the drive will turn the motor as long as it receives steps, right? I've been breaking my head about this all day and can;t seem to figure out why is even the setpoint from LCNC choppy? The joint.2.motor-pos-cmd is the origin of the signal it seems to me and shouldn't it be a smooth slope, letting the pid loop take care of reaching the values? Can;t seem to find info on what actually happens in LCNC between something like "G0C0" and joint.x.motor-pos-cmd. A bit stumped now :|

Just a quick glance... all your spindle-index-enable signal lines appear to be commented out in the HAL file.

Maybe a double-check and possibly uncomment those lines?

Yes, possibly the drive itself is responsible for the choppy movement.

What input methods are available for velocity mode?  If the drive accepts PWM, you can change stepgens to PWMgens on Mesa cards.

You also may be able to tune the drive to run more smoothly in position mode.  Perhaps the drive permits different tuning values to be changed on-the-fly by the user via inputs (or modbus)?  This might allow you to keep the drive in position mode, but have a tight tune for Caxis and a more gentle tune for spindle/velocity mode.

What is the drive mfgr/model?

Hi all,

We got our lathe to run and have been moving on to some of the finer details.We are on Linuxcnc version 2.9.2. We are using the AXIS display and have a Mesa 7i95 board. The problem we have been having is when trying to get our machine to do rigid tapping we will get to the g-code that does the rigid tapping and it will hang. From what I've understood, we need to have the at speed signal be true for rigid tapping? We have also manually confirmed that the spindle index enable will go low when it reaches one specific point on the spindle. I was hoping that we could get some help with anything that might be causing this issue. I have attached our hal, ini, and the gcode we are trying to run on our lathe.

-jblanscett