Siemens SIMOVERT MASTERDRIVES Manual page 225

05.2006
7.3.5 Function "PRBS signal with recording" (function diagram 796)
Recording
Reading out
Siemens AG 6SE7087-6QX70 (Version AG)
SIMOVERT MASTERDRIVES
The free block "PRBS signal with recording" generates a pseudo
random binary sequence which can be scaled with a selectable
amplitude (U477 "PRBS-Ampl"). This signal is available on K0630.
Connector K0630 supplies a noise signal with frequency components of
0.6 Hz to 625 Hz at a sampling frequency of 5 kHz (and recording of 2
single connectors). The noise signal is called "pseudo random"
because even though the bit sequence of a cycle has no repetitions,
the noise generator always supplies the same bit sequence on each
start.
The block can record one or two channels simultaneously, physically
using the trace memory in the converter. If the noise generator is
assigned to the time slot (U953.70 = 2), the trace must be removed
(U953.72 = 20), as both are supplied via the same connectors and both
parameters and use the same memory.
Recording is always performed in T2. Unlike the normal trace, with the
PRBS signal a series of recordings (U478 "PRBS cycles") can be
started (U478 "PRBS cycles") and those recordings then averaged
through addition. As a result, random interference is averaged out and
even small noise amplitudes produce good results. In order to prevent
the value range from immediately overflowing, the DC value is derived
by an additional noise cycle that is automatically transmitted before the
measurement itself. However, if a counter overflow occurs, alarm A032
is set. The alarm is only reset when a measurement is restarted.
Monitoring parameters n479 "PRBS cycles CntD" counts the set cycles
back to 0 during measurement. In this way, measuring progress is
measured and the occurrence of alarm A032 can be detected, if
necessary.
As recording is configured and started using the same parameters
(U480, U481, U488) as normal trace, recording can be configured and
started in DriveMonitor with the Trace menu item. (Please first ensure
that the time slot for noise is activated and the time slot for the trace
bock is deactivated! U953.72 = 20 and U953.70 = 2).
In the case of DriveMonitor, item "Trace" in menu "Diagnosis" must be
selected. In the window "Settings.." you can then select the
connector(s) to be recorded. No more than the first two channels can
be activated. The "recording interval" or "trigger settings" bear no
relevance to the PRBS recording. Recording starts as soon as you click
on the "Start" button.
Compendium Motion Control
Functions
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