[gadgetwzrd]

Troubleshooting direction requested-
I have a VMC 1000/22, DX32 control, Simodrive 611 w/Siemens servomotors. When I evoke the "AXSDRV ENABLE" command via the BOSS interface, I immediately get the alarm: "Following Error Limit Exceeded". Concurrently, the Z-axis may shudder and drop the head assembly about 1/16". I observe no movement on the other axis and no fault codes appear on any axis drive module. I have replaced both the tachometer and encoder cables with new to the Z servomotor with no change in performance. The armature cable has not yet been changed but the currently installed has good continuity. The reason the cables were changed is that same problem was encountered in November and I was able to recover after reseating the Z-axis control cables. The servos have ohmed out ok. I have so far manually checked that the X-axis ball screw has expected resistance in movement. Ways appear to be lubricating properly. Is there a procedure for bypassing control and enabling each drive in order to jog that the error following can be monitored? Or should I be looking elsewhere for source of problem? Thanks to all...

[machintek]

I think when you enable the drives the Z axis drops due to gravity and because the brake releases but the Z drive/motor is not holding position.
Try the same thing in the maintenance page and see if the Z dropping causes the alarm or if the drop you see is a result or the delayed brake.
You could use a bottle jack to hold the head up to prove this. If it does not fault then release the jack and see if it drops and faults.

George