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PSI 9000 2U Series
3.10.10 Arbitrary function
The arbitrary (freely definable) function offers the user further scope. Up to 100 sequence points are available for
use for current I and voltage U, all of which have the same parameters but which can be differently configured
so that a complex function process can be built up. From the 100 sequence points a block can be freely defined
to run from sequence point x to sequence point y. This block can then be repeated 1...999 times or endlessly. A
sequence point block is only applied on either current or voltage, thus a mix of assignment to current I or voltage
U is not possible.
The arbitrary function can merge a linear progression (DC part) with a sine wave (AC part), whose amplitude and
frequency are shaped between start and end values. If the start frequency (fs) and end frequency (fe) are both
0 Hz, the AC parameters have no impact and only the DC parameters are effective. Each sequence point is al-
located a time in which the AC/DC curve part will be generated from start to finish.
The following parameters can be configured for each sequence point:
Value
Range
Description
Is(AC)
0...50% Nominal value of I
Start amplitude of the sine wave part
Ie(AC)
0...50% Nominal value of I
End amplitude of the sine wave part
fs(1/T)
0 Hz...10000 Hz
Start frequency of the sine wave part
fe(1/T)
0 Hz...10000 Hz
End frequency of the sine wave part
Angle
0°...359°
Start angle of the sine wave part
Is(DC)
Is(AC)...(Nominal value - Is(AC)) of I Start value of the DC part
Ie(DC)
Ie(AC)...(Nominal value - Ie(AC)) of I End value of the DC part
Seq.time 0.1 ms...36000 s
Time
The sequence time (seq. time) and the start and end frequency are related. The minimum value
for
Δ
f/s is 9.3. Thus, for example, a setting of fs = 1 Hz, fe = 11 Hz and Seq.time = 5 s would
not be accepted as
Δ
f/s is only 2. A seq. time of 1 s would be accepted, or, if the time remains
at 5 s, then fe = 51 Hz must be set.
The amplitude change between start and end is related to the sequence time. An arbitrarily
small change over an extended time is not possible. See section „3.10.2.5. Minimum slope /
maximum ramp time“ for more information.
After the settings for the selected sequence point are accepted with SAVE, further points can be configured. If the
button NEXT is touched a second settings screen appears in which global settings for all 100 sequence points
are displayed.
The following parameters can be set for the total run of an arbitrary function:
Value
Range
Description
Start seq.
1...End seq.
First sequence point in the sequence block
End seq.
Start seq. ... 100
Last sequence point in the sequence block
Seq. Cycles
∞ or 1...999
Number of cycles of the sequence block.
Schematic diagram:
Applications and results:
St
ar
t(
D
C
)
t
A
St
art
(A
C)
Seq.time
En
d
(D
C
)
Example 1
Focussing 1 cycle of 1 sequence point from 100:
DC values for start and end are the same, also the AC amplitude.
With a frequency >0 a sine wave progression of the set value is
generated with a defined amplitude, frequency and Y-shift (offset,
DC value at start and end)
The number of sine waves per cycle depend on the sequence time
and the frequency. If the sequence time were 1 s and the frequency
1 Hz, there would be exactly 1 sine wave. If the time were 0.5 s at
the same frequency, there would only be a half sine wave.
