Eaton easyE4 Manual page 370

6. Function blocks
6.1 Manufacturer function blocks
366
Figure 180: Typical pulse profile for a stepper motor in normal mode
n1: Number of acceleration pulses
n: Total number of pulses
n2: Number of pulses for operation
n3: Number of deceleration pulses
QF: Current frequency
FS: Start frequency
FO: Operating frequency
PF: Jog frequency
Start frequency at function block input FS
The maximum start frequency that can be configured depends on the load torque. Enter
a start frequency value that will enable the stepper motor to move the load even at low
speeds. You will normally be able to find information on the maximum start frequency
without taking the load torque into account in the technical data for the motor. When the
load torque is taken into account, the start frequency must only be high enough for the
motor not to lose any pulses during acceleration and not to be driven by the load during
deceleration.
If the value of FS is set too low, this may cause oscillations
between the motor and the load. Jumps at the start or end of
the positioning section may occur if FS is set too high.
Operating frequency at function block input FO
The maximum operating frequency also depends on the load torque.
The motor generally achieves its maximum power and torque at very low speeds. The
higher the speed, the weaker the motor will be.
Jog frequency at function block input PF
The maximum frequency that the motor should be able to reach in jog mode.
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