Which mode is best for new setups?

rodw wrote:

Hmm, thats about 352 metres a minute on my machine. Now I just have to find a motor that will turn that fast! I don't think Clearpath have one.

And when you do get those motors, your LinuxCNC Step configuration will be ready!

Hi Guys,

Tonight I finally had a chance to hook my new Servo motor up to my machine and move it with LinuxCNC. It moved correctly but the motion was very sluggish. I did the Clearpath servo tuning and it moves AMAZINGLY well when I use the clearpath software to jog and move the servo. It starts out by taking up any backlash before a move then executes the move smoothly and cleanly. I can run at 1100 RPM on the servo without any problem. That translates to about 22 ipm on my machine which is fine for me. I have 16 inches of Z travel. Now the issue is this. I don't yet have HLFB turned on so I just have those wires unconnected. I'm not really sure how I would want to connect them so I will need some advice there.

As such the motor moves just fine, but the F-Error starts marching away as soon as I begin to make a move. Then after I stop the move the F-Error slowly marches back to zero and the motor stops moving.

I'm confused why and how LinuxCNC is inferring an F-Error at all? Furthermore the servo moves much more slowly than it can. Is this because of my pulse settings? The servo also moves more abruptly than it should, not nice and smooth like when I use the clearpath servo jog commands. It's like LinuxCNC commands are not using the servo tuning settings that I just completed and stored in the Clearpath servo motor.

Lastly, the servo moves very slowly yet it can move much faster as I tested in the Clearpath software. Not sure why it would be moving at only 1/3 the speed it can move.

Perhaps I need the HLFB hooked up so LinuxCNC doesn't assume it's out of position and start gaining F-Error as soon as I begin a move?

-Suggestions welcome!

Yes Z is slow but also rough (abrupt) in movements. My X and Y are performing wonderfully. Z is the oddball because it's step/dir and not encoder feedback.

I'll give the suggestion you made a try. Any idea how I can let the system use the tuning settings that Clearpath setup in my servo motor? It went through a very thorough tuning setup and then when I activated LinuxCNC it sort of seemed to ignore those settings. I can reach out to Teknic to see if they have suggestions on this but I figured I'd ask here if anyone has experience with this.

Also I'll still need some ideas on what to do with my HLFB wires. I have them disconnected at the moment because I'm not sure what to feed them into within LinuxCNC.

Wow pncconf has some nasty bugs. I already fix the DERIV lines from pncconf. Now this one too. Is there a list of known pncconf bugs that we should be on the lookout for? -I do like pncconf ...overall it appears to be really nice, but for these little niggling issues.

I believe your PID settings are wrong for the Z as well and might also contribute to the following errors.
Normally for a Mesa hardware stepgen P should be = 1000
and FF1 should = 1 (every thing else set to 0)

Excellent. I tried 300 and it was giving resonance at the end of a move but that was FF1 at 0 ...I'll try 1000 and 1 as you suggest. I couldn't find what recommended settings were on stepgen.

I assume there is no tuning to do with stepgen, especially since my Clearpath servo tuning software already did a very nice tuning from the manufacturer software. -But if I'm wrong and need to tune in LinuxCNC also, please let me know. Stepgen is new to me as I'm used to having resolvers or encoders and a LinuxCNC closed PID loop.

You are correct; there's no tuning in LinuxCNC.

Just make sure your maximum velocity and acceleration don't overload the drive. You can monitor the torque and voltage for saturation using the Clearpath software.

OK will do. Can anyone help me understand where and how I plug my HLFB wires into LinuxCNC? This High Level Feedback can do a bunch of different things but for starters I'm just looking for a simple solution that tells LinuxCNC there's a problem and causes a fault (like Follow Error) so that LinuxCNC can STOP.