ADLINK PCI-8154 - Manual (Page 57)

Operation Theory 47
If VSacc or VSdec=0, it means acceleration or deceleration use
pure S-curve without linear part. The Acceleration chart of bell
curve is shown below:
The S-curve profile motion functions are designed to always pro-
duce smooth motion. If the time for acceleration parameters com-
bined with the final position don’t allow an axis to reach the
maximum velocity (i.e. the moving distance is too small to reach
MaxVel), then the maximum velocity is automatically lowered (see
the following Figure).
The rule is to lower the value of MaxVel and the Tacc, Tdec,
VSacc, VSdec automatically, and keep StrVel, acceleration, and
jerk unchanged. This is also applicable to Trapezoidal profile
motion.
This kind of speed profile could be applied on velocity mode, posi-
tion mode in one axis or multi-axes linear interpolation and two
axes circular interpolation modes.