Servo Wiring and Tuning detailed How To example Mesa 7i77.

Yes please.
That would be very nice of you, you are much beter at explaining stuff.
Thank you very much.
With utmost respect,
Tom

Tommy,

Thanks for posting this. I am closer still to powering up my gantry (mesa cards came in yesterday) and I will be following this thread for sure. My servos are linear motors, not ball screws, and from reading the manual on my drives it appears that there is a lot of the same tuning parameters/procedures available in the servo drive it'self. Am I correct in thinking if the drives are tuned (using the mnf supplied software), then LCNC could be configured to just output a position, or would I still need to tune LCNC around the drive? The encoder wiring routes back to the servo drive & the drive then is configured to pass the encoder signal along to LCNC, so both entities have the encoder available to them.

Len

A drive that is configured to run from a position commend generally takes a digital command, like step-dir, and there usually isn't any tuning to be done in Linuxcnc. What Mesa cards did you get?

Todd,

I have the 7i93 (ethernet in, 2 50-pin out) & the 7I33TA pwm daughter card for the analog control. I also have a 7I47 for some additional IO & a side project to play with. The drives are configurable so I can configure them for velocity or torque mode and let Linuxcnc do the tuning if necessary. I take it that is the most common way of configuring Linuxcnc (with it handling motion control). I keep thinking that the motion control should be outside the PC in embedded hardware, but I realize that with the power of Linux & RTOS this isn't as prevalent as it once was, particularly with a FPGA doing some of the heavy lifting in between.

I originally thought that the drives were doing the motion control in this machines existing setup, but after studying the current setup in more detail, they aren't. They are receiving an analog voltage from a PCI motion card (similar to Mesa, but not supported by Linux CNC), so replacing that card with Mesa hardware and some tuning should get me going.

Len

In that case you should be good, and you shouldn't need to mess with the drive tuning, as it should have already been done. Just tuning the position loop in Linuxcnc.

superlen wrote: The drives are configurable so I can configure them for velocity or torque mode and let Linuxcnc do the tuning if necessary. I take it that is the most common way of configuring Linuxcnc (with it handling motion control). I keep thinking that the motion control should be outside the PC in embedded hardware, but I realize that with the power of Linux & RTOS this isn't as prevalent as it once was, particularly with a FPGA doing some of the heavy lifting in between.

The most common setup is a velocity-controlled servo drive (velocity loop in the drive, an tuned in the drive) and a position loop in LinuxCNC (tuned after the velocity loop is tuned)

The fundamental point of EMC (which became LinuxCNC) was to be a motion controller that ran on commodity PC hardware rather than on specialised hardware. Whereas Mach3 had commercial reasons to support external motion cards like the Smoothstepper, LinuxCNC has no such commercial incentives, so the philosophy is that LinuxCNC is a motion controllerm and if you don't want it to do that, then use something else. But I digress.

after studying the current setup in more detail, they aren't. They are receiving an analog voltage from a PCI motion card (similar to Mesa, but not supported by Linux CNC),

Are you sure? What card is it?