encoders with steppers

[turmite]

I know that most all stepper systems are open loop, but I have a question I need answered. If you installed encoders on the back of steppers like in servo systems, and used the glass scale abs positioning encoders can you make a closed loop system out of steppers? Ok maybe more than one question. When using servos with the rotary encoders only, don't you just have a more powerful open loop system? I know the Gecko drivers will fault if the system gets so many steps out but does it just shut off or does it actually try to gain or lose steps to correct?

Mike

[balsaman]

With gecko servo drives it's closed loop back to the drive, but not the controller (computer). It will not make any corrections. The gecko will allow a 128 step error as it tries to follow the stream of pulses from the computer, if it goes beyond the 128 step error, it quits. The nice thing about it is if it can't get there, you will know about it, and the gecko can let the controller know about it too. The part may be toast but you know it right away.

With steppers, you may be loosing steps, but won't know it till after you are done running the 3 hour gcode and measure it.

Eric

[turmite]

Thanks Eric.

Mike