Calculating The Profile Table Values - Siemens SIMATIC S7 System Manual

Program instructions
7.7 Pulse output
7.7.5

Calculating the profile table values

The multiple-segment pipelining capability of the PTO generators can be useful in many
applications, particularly in stepper motor control.
For example, you can use PTO with a pulse profile to control a stepper motor through a
simple ramp up (acceleration), run (no acceleration), and ramp down (deceleration)
sequence. More complicated sequences can be created by defining a pulse profile that
consists of up to 255 segments, with each segment corresponding to a ramp up, run, or
ramp down operation.
The figure below illustrates sample profile table values required to generate an output
waveform:
● Segment 1: Accelerates a stepper motor
● Segment 2: Operates the motor at a constant speed
● Segment 3: Decelerates the motor
To achieve the desired number of motor revolutions for this example, the PTO generator
requires the following values:
● Starting and final pulse frequencies of 2 kHz
● A maximum pulse frequency of 10 kHz
● 4000 pulses
During the acceleration portion of the output profile, the output wave form should reach
maximum pulse frequency in approximately 200 pulses. The output wave form should
complete the deceleration portion of the profile in approximately 400 pulses.
①
②
③
294
Segment 1: 200 pulses
Segment 2: 3400 pulses
Segment 3: 400 pulses
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART