Festo Контроллер двигателя SEC-ST - Manual (Page 13)

Contents and general instructions
XI
Festo SEC−ST−48−6−P01−EN en 0606c
Basic information
Despite the simplicity of the stepping motors, it should be
mentioned that it is not a controller. The control system does
not receive any kind of acknowledgement whether the motor
has, in fact, performed its step.
And so it is extremely important to dimension the motor using
its speed−torque characteristic curve. This ensures that the
applied load can, in fact, be moved by the motor with the
specified acceleration and speed.
If the motor loses a step, that is, if the applied load is greater
than the force the motor can produce, the part to be positioĆ
ned is no longer in the desired position. Errors that must be
monitored in the overall system, such as through limit switĆ
ches, can thus occur.
Start−stop frequency
Another important variable in the use of stepping motors is
the so−called start−stop frequency. It is the frequency or
speed at which the stepping motor can safely, that is, without
loss of step, start and also stop again under the torque to be
provided.
Losses of step can occur when decelerating (stopping) just as
much as when accelerating!