Setting
up Compax3
C3I20T11 / C3I32T11
254
192-120103 N13 C3I20T11 / C3I32T11 December 2010
4.4.9.6
Measurement of frequency responses
In this chapter you can read about:
Safety instructions concerning the frequency response measurement ........................... 254
Functionality of the measurement .................................................................................. 254
Open/Closed Loop frequency response measurement .................................................. 256
Excitation Signal ............................................................................................................ 257
Non-linearities and their effects ..................................................................................... 258
Please note that you require a
license key
(see on page 246, see on page 244)
for this application!
Safety instructions concerning the frequency response measurement
During the measurement of the frequency response, the control is changed and
influenced in multiple ways. You should therefore respect the following notes:
During the measurement, the entire system is excited via a broad frequency
spectrum. This might damage especially sensitive components (such as lenses)
The risk increases with the extent of the excitation. In addition, natural
mechanical frequencies may cause an increased excitation of individual
components.
The measurement of the frequency response can only be made in the setup
mode with energized controller.
During the current measurement (between start and stop of the measurement),
no write flash may be executed.
In the event of a break in communication during the measurement, the controller
must be switched off and then on again in order to reestablish the original status.
Changes of the controller parameters during the measurement are not permitted.
Those may be overwritten by standard values when the measurement is
terminated.
Functionality of the measurement
Basic structure of a frequency response measurement
System S
G(S)
Input
Eingangs
Signal u(t)
Output
Ausgangs
Signal y(t)
Signal
Generator
Signal Processing
Signalauswertung
Amplitude spectrum
Aplitudenspektrum
Phase spectrum
Phasenspektrum
V(f)
ϕ
(f)
Superimposed
überlagertes
System
+
open/closed
Loop
C3 Software-
Oscilloscope
Upload
In general, the analysis of the dynamic behavior of a system is made by analyzing
the input and output signals.
