[CAD_CAM_EDM_DRO] Runaway servo questions

While running the mill today and thinking about the runaway servo issue should an encoder fail. I wondered if an electronic device could be designed that mounts between the servo leads and the A/B signal from the encoder. It would monitor the pulse train to the servo and the signals returning from the encoder. Then be tied into the E-stop circuit of the control. If a pulse stream was present and a A/B signal stream was absent it would break a connection and make the E-stop circuit drop out. Having hard limits at the extremeties of the envelope seem to be the only protection available and could result in alot of damage before it ever got there. That would be great if something would monitor and trip in a very short distance in the event of a lost encoder. Or would a dithering servo situation make this impossible? If someone designed one that worked, I'd be the first customer. Someone mentioned that Geckos fault after a 128 step/count discrepancy. I've heard and seen Marriss mention
the runaway servo issue and dont recall him saying it will stop in a short distance. He stresses hard limits at the ends of the travels.

Ron



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