RMS Technologies R325P DRIVER - Manual (Page 19)

11. Appendix B: PF Value
For applications requiring ultimate smoothness of motion and extreme accuracy, the R325P
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 3):
0 = Slow Decay
1 = Mixed Mode 15%
2 = Mixed Mode 48%
3 = 100% Fast Decay
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
R325P User Manual Page 19 of 20 5/29/2013 Version 1.01