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First time retrofit to linuxCNC, using pncconf to tune the PID loop.

Any advice would be great on initial pid settings.

glentek velocity/tach servo amplifiers SMA7215 
Single ended 1000ppr encoders

Critical response achieved on each servo amp, it is not overdamped yet when i adjust I/D/BIAS/DEADBAND it overdraws

Any advice for first time setup would be very much appreciated

 

In short:
RPI can do at most 20000 steps per second, if lucky and with a bit of fiddling (this is from what i read here, i stopped using RPI since version 3B)
Mesa can do 10000000 (10 million) steps per second on any or all pins, if pushed, does 1-4 million for years on end, can use any pin as input or output, does steps, encoder counts, PWM, on any pin (the FPGA part), can be programed as needed, extremely reliable (i have over 80 or 100 or i have no real clue in daily use on industrial machines weighing several tones without a single issue ever for many years), and by far the best support on planet earth in the form of PCW.
Yes i am biased, from experience, no i am not payed by them, and yes any price you see for Mesa boards i have to pay at least twice that, and i pay it gladly for the piece of mind i get with them, i can sleep calmly without worrying something might fail.
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As for RPI, i personally use old "enterprise" PC's and some laptops, so if you can find such things it is another alternative, i can get Lenovo T470 for 120-150 euro, with 14" touchscreen, battery, plenty of RAM and NVME, with built in network jack, for me this is much cheaper than any RPI combo and more powerful and usable.

What version of linuxcnc?

Hab mich Undeutlich ausgedrückt.. G54 hab ich auf die Bohrung gesetzt.,auch auf der Ecke mit G54 das selbe Ergebnis. Für beide hab ich jeweils einen G Code Generiert. Problem hab ich Temporär gelöst durch Antasten der Bohrung und setzen des Nullpunkts G55 auf die Bohrung. Anscheinen ist es immer ein Problem wenn ich den Nullpunkt auf G54 setze.

Huh... I've not experience a properly powered and cooled rPi going bad. Maybe I've been real lucky?

Does the Mesa support tighter step timing accuracy than the "base thread" step generator?

I was not aware that the Mesa gave improved performance? Is there a reference-able document that gives a *quantitative* analysis of this performance gain?

Thank you,

BB

Ahh, well, so it goes. I've ordered a 7I76U because I think that the D models were actually going to be more difficult to wire anyways, as I'd like some sourcing outputs.  I'll see about getting an RMA for the 7I77D I have, and can function test the existing 7I76D when I get the new 7I92TM.  5 axis + spindle and 48 I/O pins should be plenty to get this mill up and running, and that leaves me some boards to experiment with in the future

Thanks for the quick replies, nice to keep momentum up on the project!

Put it this way, if the RPi5 goes bad for whatever reason, you'll have to get a new Raspberry whatever, but if you go with the 7i96 any machine with an Ethernet Port will slip in, copy your config over and you're good to go. Hardware step generation, Mesa, et al, will be smoother than software step generation.

Apparently it fell asleep!

Good evening,

It appears the Wiki is having trouble. Is there an alternative place to get the information?
I am getting a "Site not found" error.
I cannot figure out how to include a screenshot.

Thank you,
-T

Hello all.  It's been a couple of years since I got my machine, a 3 axis knee mill with steppers and linear encoders, working and I'm now finally getting around to something I've been wanting to do for a long time but I've probably forgotten most of what I learned while setting up this system and would rather not break it so I thought I'd ask first before I start tweaking the cfg/ini files. 

The goal is to increase the accuracy.  When I command it to go to a position it gets close (within .001) but I'd like to halve that if not better.  Do I remember correctly that this is the DEADBAND value in the .ini file?  It's presently set to .001 (at each joint), I have 5um encoders which my notes say corresponds to .0002" so I'm thinking I could go to a DEADBAND value of .0005 and maybe all the way to .0002.   My stepper controllers are presently set at 200 steps/rev, I can increase that by A LOT with DIP switch settings.  I have .200"/rev leadscrews and 1:2 pulleys (big one on the leadscrew) so one motor rev is .100" of movement.  At 200 steps/rev that corresponds to 2000 pulses per inch which is what I have for the STEPGEN_SCALE value.  That means I have .0005" per step.  So that has me worried that changing the DEADBAND value to .0005 might cause it to start oscillating since I'd be requiring that it gets withing one pulse.  Does it make sense to change the stepper controller DIP switches to 1000 steps/rev  and the STEPGEN_SCALE to 10000 to avoid this?  That would change it to .0001"/pulse which is smaller than the encoder.  Does the position feedback handle the situation where it sends multiple pulses before it sees a change in the encoder?  If I change the DEADBAND and STEPGEN_SCALE values in the .ini file do I have to change anything in the other files to correspond with this? 

Am I correct that this likely changes the max speed I can run at.  What breaks it I try to jog it too fast.  I'm presently using these values:

STEPGEN_STEPLEN = 2000
STEPGEN_STEPSPACE = 2000
STEPGEN_DIRSETUP = 2000
STEPGEN_DIRHOLD = 2000
STEPGEN_DIRDELAY = 4000
STEPGEN_MAXVEL = 0.25
STEPGEN_MAXACCEL = 0.25

BTW, all three axis are the same.

thanks in advance for any input
 

Just seeing this now. No I did not find another way. It works for me with the extra integration loop. My purpose was to machine some parts. I contacted lichuan and they said everything was fine on their test stand. It is sort of good to see someone else has the same issue. I have no other idea how to resolve it.

If you have field power and neither CR15 nor CR16 light, its possible the 7I77D was damaged as well.
 

Thanks for that clarification, unknown!

I’m running Meanwell PSUs so very glad to hear the vote of confidence in those. Also good to know your powering sequence, and that the DB25 powering solution is the preferred one. 

I got the chance to power the 7I77D today, and discovered that it lights CR1,3,6, and 7, but CR15/16 never light. Confirmed with both my meanwell supply and my bench supply. I’ve ordered a 7I92TM and will RMA the 7I92T I have, but this would appear to mean that the 7I77D is not functional. I don’t think I have a machine with a parallel port on it, so I’ll likely wait until my new 7I92TM arrives, verify it works, and then connect it to the 7I77D and attempt to reflash the firmware on it. Does that seem like the right approach? Or does CR15/16 not lighting mean that board is also probably damaged and needs RMA as well? 

Thanks! 

 

I started a place to document gladevcp builtin panels:

linuxcnc.org/docs/devel/html/gui/gladevcp-panels.html

Feel free to add some more detail for people to understand how to add your probe screen.
And thanks for adding your small probe panel!

Thanks Andy.

Is the rPi GPIO interface considered fully baked, or is the Mesa 7i96S the smart bet? I would totally love to avoid the $150+ for the Mesa, but only if that does not then cost me an additional $300 in labor time.

BB