Calculating The Profile Table Values - Siemens Simatic S7 Series System Manual

Control
register
(Hex val-
16#C1
16#C4
16#C5
16#E0
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
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
Enable Select
mode
ue)
Yes PTO
Yes PTO
Yes PTO
Yes PTO
Result of executing the PLS instruction
PTO Time base
Segment
operation
Single
Single
Single
Multiple
Program instructions
7.7 Pulse output
Pulse Pulse
count width
Update
Update
Cycle time
/ frequen-
cy
Update
frequency
Update
frequency
255