mshaver Posted February 17, 2014 Posted February 17, 2014 There is a great example of a stepper setup using ACC24E3 located at http://forums.deltatau.com/showthread.php?tid=768&highlight=pulse+and+direction+example Can anyone provide a similar example of a stepper setup using Acc24E2A? Would be much appreciated. M. Shaver mshaver@pekoprecision.com
curtwilson Posted February 17, 2014 Posted February 17, 2014 The User's Manual chapter on Basic Motor Setup as a section on "Setting Up Power PMAC for Pulse-and-Direction Control" that covers both the older and newer interfaces in detail.
mshaver Posted February 17, 2014 Author Posted February 17, 2014 Let me ask a few more specific questions. I am using Parker stepper drives. The Parker drives take care of microstepping, ie; I can set the Parker drives to take the step pulses from the DT and turn them into various fractional microsteps. There are no encoders on the stepper motors. However, the motors drive linear stages and the linear stages have linear encoders that I will be bringing back to the Delta Tau as the outer loop position feedback. I will not be using current feedback of any type. Based on this, do I need to do anything at all with regard to phasing in the delta tau? I view phasing as coming into play if I want the DT to do commutation, current feedback, or to create the microstepping, which, in this case, will be done by the Parker drives. Based on this, what else can the PPMAC bring to the party with regard to phasing?
curtwilson Posted February 18, 2014 Posted February 18, 2014 If you are using the Parker microstepping drives, the PMAC has nothing to do with the commutation or current loop tasks. It simply provides the Parker drive with a series of pulses, one per microstep. I advise you to set up the motor initially in open-loop microstepping mode, feeding back the pulse train into the encoder counter as simulated feedback. This should be easy. Once you have this going, you can switch over to using real feedback from an external encoder. This can be trickier, especially if the count resolution of the encoder does not match the microstep resolution of the drive, which it usually does not. Often, the result will be considerable "hunting" when you want to be at rest. You will almost surely need at least a full count of deadband (Motor[x].BreakPosErr >= 1 when motor units are counts, Motor[x].Kbreak =0.0). You may have other issues as well if there is compliance and/or backlash in the couplings.
mshaver Posted February 18, 2014 Author Posted February 18, 2014 Thanks, this was very helpful and informative. M. Shaver
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