Siemens Simatic S7 Series

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