A Note on Using Copley MACRO Drives with Power PMAC

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In case this has not yet been elsewhere documented:

 

Power PMAC's default setting for EncTable[n].ScaleFactor for MACRO motors (motors whose Motor[x].EncType=4) is 1/exp2(13), or 1/(2^13). This is because it assumes you will be using a Delta Tau MACRO Station, which will perform a 1/T extension of quadrature encoders before sending the feedback information to the Ring Controller, Power PMAC. This adds 5 bits of fractional information. Thus, the upper 24 bits of the Gate2.Macro[j][k] register will contain 5 bits of fraction in its LSB. This is why the default EncTable[n].index1 and index2 both equal 8; shift right 8 to get rid of garbage at the bottom of the 32-bit register Gate2.Macro[j][k] (when viewed in C), up 8 to get the data to bit 31 of the register, and multiply by 1/exp2(13) to get the data in units of motor counts.

 

However, Copley drives do not perform the 1/T extension like Delta Tau's, so the 5 counts of fraction do not exist; we are just getting whole counts from the Copley drive. So, you should use:

 

EncTable[n].ScaleFactor=1/exp2(8)

 

when getting quadrature counts from the Copley Drive in order to have your feedback units scaled properly.

 

In addition, there are a few other Copley-specific PPMAC settings that deviate from the standard settings you would use for a Delta Tau MACRO Station:

 

Motor[x].AmpFaultLevel=1 // High true amp fault
Motor[x].CaptPosRightShift=0
Motor[x].CaptPosLeftShift=8