ADLINK Technology PCI-8254, User Manual

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Motion Control Theory 105
PCI-8254 / PCI-8258
This controller employs S-factor (S) to control jerk ratio. Its
equation is described below
Value of S is between 0 and 1, when
S = 0, the speed profile becomes a T-curve
S >0 and S<=1: S - curve
When S = 1, the profile comes to a Pure S– curve with its A-T
chart become a triangle.
The equation above indicate that the greater the value of S is the
more smooth the speed profile and the smaller jerk value will
become. This helps in reducing motor vibration. However, the
motion process takes more time to complete. On the contrary, the
smaller the S value is the greater the jerk value become and the
motion time reduces to the shortest.
As with a T-curve, when motion distance is insufficient, the
controller adjust the maximum velocity automatically to maintain
smooth movement. Acceleration ACC and DEC and S-factor
remain consistent to maintain acceleration rate and the jerk rate
will be changed, as shown in figure below