Running servos in position mode instead of analog

I'm running a DYN4 1.8K as a spindle motor geared 1:1.8 using velocity mode and +/-10V control. I rigid tap 3mm to 6mm with no problem. Never tried a DYN on an axis though.

Michael wrote: I hooked up the encoders in position mode and they still have a delay in response that can be seen in either of the attached pictures. If I use position mode will this also effect the ability to close the loop with linuxcnc and run consistently? If it does this only leave me the options to use different servos (+$$$) or to try a linear scale on each axis (+$$)

If you run position mode there should be no loop to close with LinuxCNC? Well, I guess rigid tapping could suffer a bit? Also you might need to increase following error tolerance somewhat.

Edit: I'm thinking in EtherCAT terms now, where the position is sent directly to the servo drives. If you use e.g. Mesa cards as stepgens to generate step/dir signals, then you're still running in a kind of velocity mode I guess? So you might still have problems.

JohnnyCNC wrote: I'm running a DYN4 1.8K as a spindle motor geared 1:1.8 using velocity mode and +/-10V control. I rigid tap 3mm to 6mm with no problem. Never tried a DYN on an axis though.

Would you be able to use the halscope on the motor and check of there is a delay between velocity command or analog out and encoder velocity. Just curious.

Michael wrote: Would you be able to use the halscope on the motor and check of there is a delay between velocity command or analog out and encoder velocity. Just curious.

Yes, it would sure be interesting to find out whether the 5 ms delay is in sending a motion command to the motor, or in getting the feedback from the encoder through the drive to the Mesa board. If the latter, maybe the encider could be hooked directly to the Mesa board and copied to the drive.

The delay sounds like the delay is “normal”. Oak boards adjust the delay during setup. Same with other drives with absolute encoders. Is there a way to do the same in LinuxCNC?
Still I would try to tune the drives after the Auto Tuning. I went way up with the Main Gain to 40, Speed Gain to 35, Torque Filter to 127, MaxAccel to 127 this really helped with the F-Errors at the start.

jmelson wrote:

Michael wrote: Would you be able to use the halscope on the motor and check of there is a delay between velocity command or analog out and encoder velocity. Just curious.

Yes, it would sure be interesting to find out whether the 5 ms delay is in sending a motion command to the motor, or in getting the feedback from the encoder through the drive to the Mesa board. If the latter, maybe the encider could be hooked directly to the Mesa board and copied to the drive.

It thought about it too. Unfortunately they use a Absolute Encoder, aka serial. We may can use a FPGA to sniff the signal before it goes to the drive. Or generate a signal and read the output.