Siemens SIMATIC S7-200, Системное руководство, Страница: 294 / 866

Program instructions
7.7 Pulse output
S7-200 SMART
294
System Manual, V2.3, 07/2017, A5E03822230-AF
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
Segment 1: 200 pulses
②
Segment 2: 3400 pulses
③
Segment 3: 400 pulses