2-174 Speed Reference
For example, if the following parameters are set:
[Analog In x Hi] = 10 V
[Analog In x Lo] = 0 V
[Speed Ref A Hi] = 45 Hz
[Speed Ref x Lo] = 5 Hz
then the speed command for the drive will be linearly scaled between 45 Hz
at maximum analog signal and 5 Hz at minimum analog signal. See
additional examples under Analog Inputs on page 2-12
.
Polarity
The reference can be selected as either unipolar or bipolar. Unipolar is
limited to positive values and supplies only the speed reference. Bipolar
supplies both the speed reference AND the direction command: + signals =
forward direction and – signals = reverse direction.
Trim
If the speed reference is coming from the source specified in [Speed Ref A
Sel] or [Speed Ref B Sel], the a trim signal can be applied to adjust the
speed reference by a programmable amount. The source of the trim signal is
made via [Trim In Sel], parameter 117 and can be any of the sources that are
also used as references. [Trim Out Select], parameter 118 selects which of
the references, A/B will be trimmed.
If the trim source is an analog input, two additional scale parameters are
provide to scale the trim signal.
Figure 2.35 Trim
Trim Enable Select
+
+
+
+
Trimmed
Reference A
Trimmed
Reference B
Reference B
Reference A
Tr im
A
B
Both
None