RMS Technologies R325 DRIVER W/PDT - Manual (Page 19)

RMS Technologies Page 19 Version 1.21
R325 Single Axis Driver Manual 08/23/2007
12. Appendix B: PF Value
For applications requiring ultimate smoothness of motion and extreme accuracy, the
R325 driver can be programmed via RS485 to change the Percent Fast Decay rate,
or, the PF value.
The Percent Fast Decay default is 2, or a mixed mode of 48%.
Mixed mode is a damping technique done to the driver IC. The following values
indicate the choices for Percent Fast Decay:
PF Values (0 through 4):
0 = Fast Decay
1 = Mixed Mode 15%
2 = Mixed Mode 48%
3 = 100%
Generally speaking, applications that run at slow speeds are recommended to use a
PF value of 1 or less. Fast speeds should use a PF value of 2 or more. Since the
best PF value is dependent on the motor winding, loads, power supply voltage, and
other factors, it is best to use an oscilloscope and a current probe device to view the
current waveform and try different PF values. The following examples show good
and bad waveforms when choosing different PF values.
• PF value 1
• Slow speeds
• Good waveform