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P value for stepper systems should never be changed, and it depends only on servo period timing, so for a servo period of 1000000 (1 million) it always should be 1000.
Servo period should also never be changed, except in some situations, like when using torque mode servo systems that benefit from faster iteration, or when using a PC with very bad latency. And whenever servo period is changed, so should the PID values.
The math there is 1/servo period in nano seconds, so for
1000000 servo period = 1000 P value
500000 servo period = 2000 P value
2000000 servo period = 500 P value
That is all for steppers in position mode, for servos and steppers with encoder feedback to LinuxCNC those values must be tuned.

Pncconf initially sets the P value for stepgens to 1/servo_period in seconds
(so 1000 for a 1 ms servo thread)

The physical meaning of this is that any position error (due to differences
between LinuxCNCs and the FPGA card clock, jitter, and the time
between reading the stepgen position and updating the velocity register)
is corrected by the next thread invocation.

A P value higher than 1/servo_period will overcorrect, and a a value higher
than 2/servo_period will result in oscillations.



 

Great news! It works now!, that P value was definitely the issue. I set my P value to 1000 as advised and the machine operate perfectly now!,

Is the P value something i calculate based on my jitter servo value or is that just a fixed value of 1000? 

For example, if my servo thread jitter reads 15586, would that mean my P term should be 15.586? (15586 divided by 1000?) 


I appreciate all you guys help so much , you are amazing and i apologize for being a noob. I'm doing my best to learn and im getting better everyday, thank you all so much!

Now i have to get a few things polished up and tune it all in. I am so excited!!

I'd love to know why the PNFconfig generates that as the P value? All the DIY's i followed never mentioned that P value was something i had to modify/tune.

Hmmm that's a weird one.

At a guess it could be a local hardware issue that manifested itself when you made the changes. As this is a guess I could be wrong.

Many many moons ago I had a PSU fail when I did an upgrade from Win2k to WinXP. I think the gremlins that lived in the PSU thought it would be funny to push the fail button just after I did the upgrade. They seem to like Linux more.

One thing you might try is setting the PID MAX_OUTPUT to say 9.5 (95% of full scale)
As the 7I40 cannot have 100% duty cycle (the high side MOSFET bootstrap
requires a continuous PWM signal)

There's this thing called google, you can look up acronyms and find out what they mean. Or you can read the data sheet applicable to your FPGA.

The ones you mentioned are the easy ones, there's a whole raft of others if you want to start messing around with FPGAs. Which is what you are doing, everytime I start on a project I'll have a look at he datasheets of the components involved.

You really need to have a curious mind once you start going down that rabbit hole.

I did test it. But i cheated hooked up 10v to the spindel to make it run correctly.

Think Im going try and get an U

my1987toyota wrote:

Shotcut for me. it's open source and works .

It's got AI now, oh goodie !
www.phoronix.com/news/Shotcut-24.10-Released

7I96S firmware with stepgen indexes 0,1,2 on isolated inputs 8,9,10

I figured 3 index inputs would be more generally useful and if you
just want 2 (0,1) indexes and need all 9 remaining isolated inputs
you can use  gpio.010 instead of inm.010




Note that there is standard firmware (7i96s_sdid.bin) that has all 5
stepgen index inputs on the P1 expansion connector (but these are just
unprotected 5V TTL inputs)

 

Here's another similar post:    forum.linuxcnc.org/qtvcp/40992-qtdragon-...tion?start=10#212164

I don't understand how or why var #5223 is being set to -321.00 in my VAR file. Makes no sense since my entire travel along Z is much less.

Still searching for a fix on this issue.

Setting tandem axes is done when homing. It is all covered in the documents under the heading "Homing Configuration"
You need to read it a few times before it sinks in.
each tandem joint needs a negative HOME_SEQUENCE

I would love to use NativeCam in LCNC as it seems like the best way to generate easy/moderately complex gcode for directly on the control.
Modeling the part and using CAM interrupts my workflow too much.

Keep posting here when you get it to work correctly

From inductive sensors, measuring from ballscrew pulley. Should be slow enough I think.

Here's the files.   I'll work on verifying the encoders shortly.  

The config is for metric units but velocities and accelerations seem to be set for imperial units as they are way to low for metric, max speed is 60mm/m as is.
Also, old config, so what version of LinuxCNC is being used, see the top border when LinuxCNC is running.