Re: Seeking CP3 Control Box with V2 Chip

Howard Hedlund

Periodic error is a mechanical characteristic of a worm screw gear.  A PE curve is simply a measurement of that error.  It's validity for making corrections is entirely dependent on the synchrony between the worm's actual physical rotational position and the position address in the GTOCPx.  This is often referred to as its phase.  The worm screw is not indexed.  The GTOCPx can only assume that this synchrony is maintained and is correct.  It cannot ascertain that positional or phase value afresh.  This is where the difficulty arises in swapping control boxes.
It does not matter if the axis is moved or kept perfectly still.
It does not matter that the old curve was saved and reloaded into the new box.
There is currently no way to re-establish the proper phase when you swap boxes (...or when you move the gears by hand without the servo, or when you do anything else to break the phase synchrony.)    
This will soon be a problem of the past.  There will be a solution using the AP SerialUtility.jar.  I believe that all we need at this point is for me to get the time to write up instructions and do a little more testing. 

Join to automatically receive all group messages.