Dynomotion Forum

Greetings,

I am finishing up a 4X8 CNC router using Teknic servo motors, and a cheap Huanyang VFD and spindle. Everything runs great... until I turn the spindle on. At that point the servo motors start to error out with "Incorrect Step Sequence" errors. Sounds a lot to me like I am picking up noise on the control cables.

About My setup:
1. Teknic servos have the drive built into them. The 15 feet of cable between the KFlop and the servo is connected with shielded cable. I soldered a wire to the braid of the cable inside the control cabinet and grounded it to the earth ground in the cabinet. I am running open collector as described in the in the dynomotion guide.

2. Spindle - Also braided shield cable. On the motor side the braid is grounded to the body of the spindle, in the control cabinet I soldered to the braid and wired it to the earth ground in the cabinet.

I thought I was following good grounding principles, yet I still have problems. They are absolutely tied to when the spindle is on. Anyone have any ideas?


Thanks,

Scott

Hi Scott,

Please post the manual for the drive.

How are the Step/Dir signals wired? Any pull up resistors?

What does that error indicate?

I think it might be better to connect the cable shield to the Drive's digital GND at the Drive's end of the cable only rather than Earth GND. If Earth GND is noisy it could be inducing noise into the signals.

Here is the manual, I did add some resistors like the attached image. Two resistors wired directly to the Step / Direction inputs on JP5 connecting to 5V+. Didnt change anything.

https://teknic.com/files/downloads/clea ... manual.pdf

Error Code:
Step Input Timing Error
Yellow - strobe Shutdown Disallows motion Servo off Toggle Enable input
Possible causes: Step input
pulse width too short, electrical
noise, loose connection, shorted
wires.

Thanks!

Scott

Hi Scott,

The Drive accepts Quadrature Input Mode as does KFLOP. You might try that as it eliminates certain timing issues.

But then if it only occurs with the Spindle running it is likely noise from the Spindle.

Did you try what I suggested with the shield?