Applied Motion STM23R-2ND - Manual (Page 19)

19
STM23R Hardware Manual 920-0056C
5/5/2015
Step 3: Load Inertia
The STM23R includes anti-resonance and electronic damping features which greatly improve motor perfor-
mance. To perform optimally, the drive must understand the electromechanical characteristics of the motor
and load. Most of this is done automatically when the motor and drive are assembled at the factory. To further
enhance performance, you must set a switch to indicate the approximate inertia ratio of the load and motor.
The ranges are 0 to 4X and 5 to 10X. Please divide your load inertia by the STM23R rotor inertia (82 g-cm 2 ) to
determine the ratio, then set switch 7 accordingly, as shown. For assistance in calculating the load inertia of your
application contact our Applications department.
Step 4: Step Size
The STM23R requires a source of step pulses to command motion. This may be a PLC, an indexer, a motion
controller or another type of device. The only requirement is that the device be able to produce step pulses
whose frequency is in proportion to the desired motor speed, and be able to smoothly ramp the step speed
up and down to produce smooth motor acceleration and deceleration.
Smaller step sizes result in smoother motion and more precise speed, but also require a higher step pulse fre-
quency to achieve maximum speed. The smallest step size is 1/25,000th of a motor turn. To command a motor
speed of 50 revolutions per second (3000 rpm) the step pulses frequency must be 50 x 25,000 = 1.25 MHz.
Many motion devices, especially PLCs cannot provide step pulses at such a high speed. If so, the drive must be
set for a lower number of steps per revolution. Sixteen different settings are provided, as shown in the table on
the following page.
Please choose the one that best matches the capability of your system.
7
5-10X
7
0-4X