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Incorrect Velocity, But Correct Position


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I am having an issue where the axes are moving the correct amount, the counts are proper, but the velocity is reported significantly (~1.8x) slower at the PowerPMAC vs reality. It's appears systemic to all of my axes. I confirmed it by watching the speed in the drive software, and also with a tachometer. For now I am debugging a rotary axis, since it's safer that the linears.


My Setup:

Copley Xenus Plus MACRO

ACC-5E (Gate2?)

Rotary Axis with 11,840,000 counts per rev


PPMAC Configuration

Encoder Conversion Table

Single 32 bit read

LSB Bit #: 8

# Bits Used: 24

Result Units Per LSB: 1

index1: 8

index2: 8

Scale factor: 1/256 (0.00390625)


Other Parameters



Motor[x].pEnc = EncTable[x].a

Motor[x].pEnc2 = EncTable[x].a


Xenus Configuration

Network Configuration

Position Output Scaling: OFF


To Recap. The above configuration allows me to position correctly, but the reported velocity is slower by a factor of about 1.8. Any thoughts or suggestions would be greatly appreciated!

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Found the issue. Because the ACC-5E card is running a different PWM period, I needed to change the sys.servoperiod accordingly.


default: Sys.ServoPeriod=0.44274211









0.44274211/0.24993896484375 = 1.77

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