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Checked a few things- still need to check filddling with error limits on the servo (requires me to dredge up and set up a Windows PC by the mill- servo software doesn't play nice with WINE):

• "Differential" noise isn't quite as bad as it initially looks- yes, still awful, but mostly the noise between the A+/A- pins at the servo end is in phase. The high-frequency noise that is out of phase is well below the minimum step time (750 ns). So... awful, but I think "OK". At least seems less likely to be the problem. See picture with math in it, measured at the end of the cable right where it would connect to the motor.
• Tying the A- pin to GND (single-ended signals instead of pseudo-differential) mostly just gives different noise, similarly bad. See picture without math in it, measured at the end of the cable right where it would connect to the motor.
• The noise gets far worse when I disable the e-stop on the machine. The e-stop removes power from the spindle drive and servos, so could be either one- though disconnecting the servo power plugs individually had no impact on noise. Spindle is a DMM DYN4 with all the recommended filtering on the power inputs, but still could be a problem.
• Drive strength seems OK- the 0-5V transitions are really sharp.
• Connectors do tend to be the bane of happiness (or at least reliable signals), but they seem to check out OK. Crimps all seem good (can pull on them with no movement), soldered joints all look fine, connectors are clean, secure, and haven't been exposed to any contaminants. All signals are reading ~0.3 ohms from the end of the cable to the screw terminal on the 7i76E, which is maybe 0.1~0.2 ohms higher than I get just touching the DMM leads together. I retorqued the screw terminals, which made no difference.
• I disconnected the servo from the leadscrew and turned it by hand. It appears to be slightly bent- not enough that it's hard to turn with my fingertips poking on the coupling, but definitely goes through phases of being easier/harder to turn. Might replace that on principle since it's easy to do and "not right", but it's not obviously the issue.

Will test removing spindle power to see if that's the signal noise issue, and also see if powering the 7i76E from an isolated 5V supply impacts anything. Should've tested those before posting this, but they just occurred to me now. (also changing the motor error threshold)

Thanks all for the help, even though it's not AFAICT LinuxCNC related! Really helps to have outside eyes on problems when your head is in the weeds.

www.ebay.co.uk/itm/235834215889

In addition to the two polarities that need to be right
(TX to REQ and RX to data) The DPLL needs to be setup to
start the transfer _before_ LinuxCNC reads the data

I'll try and dig up a sample FANUC hal file Monday
 

Some debugging. Per update above, mechanically things seem fine- I can shove the Y axis around and it's definitely not moving as much as the undercuts previously mentioned. I measured those, and the deepest is maybe ~0.01"/10 mil/0.25mm. Not as bad as I thought, still entirely unacceptable.

See attached pictures for some scope traces of one of the Y axis quadrature phases. Note that the measurement setup wasn't great for this, so there might be more noise represented here than is present in normal use- scope leads were dangling from jumper wires wedged into the cable ends, so... yeah.

With nothing moving, the signal idles at 5V +/- ~1.2V. Moving the X axis doesn't seem to influence this at all. Enabling the spindle adds some noise, dropping the signal as low as 2.3V. That's quite possibly enough to create false motion- minimum input to the servo is listed at 4V, but it also says it has digital filtering against noise, so... who knows. I should look at both A and B phases at once, but ran out of time. The fourth picture shows the Y axis moving- it's pseudo-differential, which in this case I don't think is actually buying anything, since the motor inputs are opto-isolated.

All of the above seems suboptimal, but I'm not seeing how it would somehow create extra steps in -Y, then somehow seemingly exactly recover them when going to +Y. Unless I want to level-shift, I'm not aware of a way to get the 7i76E to output > 5V on the motor control pins.

Anything else I should check? I'll plan on getting traces of both A and B phases simultaneously. Is a 3D model of  the issue still helpful, or is the cross-section sketch sufficient?

I have created a basic .hal and declared the Fanuc channel, see attached .hal.

I am getting an error on startup of linux cnc:
 

When I watch the corresponding hal pins and turn the encoder I am not seeing any activity.

Any tips on what to check or adjust next will be greatly appreciated.

Hi All,
  I have been reading this forum for weeks now, and have managed to solve most of my problems without needing to ask a stupid question, But the time has come. Be gentle, this is my first post.   I will attach my files to this to help.
Current Setup:
Dedicated computer running Linux Mint Debian Edition 6 "FAYE"
LinuxCNC 3.4.1
Gmoccapy gui
3040 Chinese CNC controller.
XYZ motion, although it also had the forth Axis, I am not including that in my setup.
7i76E motion controller card
0-10V AVI
24000 RPM
800W water cooled Chinese spindle.

My files have been created with the PNCCONFIG wizard.
I have now reached a point where every time I run the wizard, it breaks something, and I have to roll back changes.
(Even when I change NOTHING, just click through the wizard, it still breaks my setup, and will not start.)

I have been carefully trying to edit my files manually, baby steps, and backups!


PROBLEM:
I am having trouble getting the spindle to correctly work in the Gmoccapy display.
I can turn on the spindle, and turn off the spindle
I have the spindle start at 5000 RPM, and this works.
The bar graph on the bottom shows  "5000                  0                  24000"
It starts at 5000, as that is my (min) setting, and the "0" in the middle would display a percentage if I could only increase it.
I cannot adjust the speed of the spindle in the Gmoccapy GUI as there are no speed controls.

I want to add speed controls. and I have tried to understand what is written here in this post,
but I just cannot get my head around what I am doing wrong.

May I ask a member here to please look over my files? Perhaps it is something easy?

Thanks in advance!
Swanie

 

Firmware flash successful.

All wired up to the RS-422 connector. I will see if I can figure out how to put an instance of Fanuc Encoder on the .hal.

Any tips welcomed.

Yup, worked. Thanks. I will now proceed with the rest.

set W17 up, power cycle  the 7I97 and try again

W16/W17 is 192.168.1.121
so ping of 10.10.10.10 will fail because there's no device with that address
and ping of  192.168.1.121 will fail because there's no route because of the host setup

Haven't gotten very far... can't seem to connect correctly to the 7i97 card. Here's what I know:

-Setup via 'edit connections' gui
-IPv4 settings as 10.10.10.11 netmask 8, checked 'use this connection only for resources on its network' under routes.

When I ping 10.10.10.10 the LEDs flash on the 7i97 in a certain sequence and terminal gives:
No detection of ethernet board from mesaflash.

Pinging 192.168.1.121 does nothing, terminal hangs.

Jumpers W16 & W17 are both in low position.

Board was opened from factory seal this morning.

Let me know what to look for next. Thanks!

I'll try to make a better model tomorrow, but maybe the attached shows the gist of it better in cross section. The desired end result is a rectangular pocket. The result is as shown with the undercuts. The tops of both walls are in the right spots and of the correct thickness. The +Y wall is fine all the way down, the -Y wall is not. The end mill was a YG1 E5G98910 (3/8" diameter, 2-1/8" LBS, and 1/2" LOC, with a 0.345" shank, so it is possible for it to make some degree of undercut without rubbing). I'll see if I can measure how extreme the undercuts are tomorrow.

Cutting an internal pocket, climb cuts. The original material was a solid piece.

Possible multiple axes have errors, but I'm not seeing evidence of it. The one dimension in X I can measure is correct and shows no signs of misalignment between Z passes.


I agree this smells like a hardware issue- if so, it'll probably be a bear to track down. The motors are ClearPath servos, driven in quadrature mode. I believe the signals are 5V from the Mesa board, but would have to double check that. If there's some kind of encoder error, it's internal to the motor.

The cables are as provided from Teknic: motor -> cable -> soldered joint to circular connector -> connector -> soldered joint on other end of connector -> ferrule to 7i76E screw terminal. X and Y cables do run adjacent to one another (and power cables) for a few feet, and they're not shielded- though Teknic also sells 55' unshielded cables, so one might infer they don't believe it's important.

What's really hanging me up is that it seems to return to the correct place in +Y, despite apparently cutting incorrectly a variable amount in -Y.


Either way, I'll double check nothing is mechanically loose tomorrow (that would be the nicest answer) and put a scope on the Y axis signals while jogging X around, see what kind of cross-talk I get. I already got LinuxCNC 2.9.3 installed.

ETA: Mechanics appear fine- I can lean/pull on the Y axis and it'll move maybe 0.001", then springs back when I release it. Leadscrew retention nut appears tight.

Do let me know if things are still unclear.

Great, thank you. I will flash it tomorrow morning and see what I can figure out. 

 

 

Great, yes I have an unused 7i97. Let me know if you need any other info. 

Thanks! 

Actually its easier to test this on a 7I97/7I97T

Do you have a 7I97 or 7I97T?