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How to Control the Frequenc...
5.2.3 Reference Handling
The reference handling in FC Series is an advanced
mechanism that sums up references from different sources.
For more information on reference handling, refer to the
FC Series Design Guide.
Illustration 5.2 Reference Handling
The reference, or speed set point (MRV, sent via
POWERLINK), is always transmitted to the frequency
converter in percentage format as integers represented in
hexadecimal (0-4000 hex).
Depending on the setting of 3-00 Reference Range the
reference and MAV are scaled accordingly:
Illustration 5.3 Scaling of MAV and Reference
NOTE
If 3-00 Reference Range is set to [0] Min - Max, a negative
reference is handled as 0%.
The speed limit settings are depending on 0-02 Motor
Speed Unit and can be set to RPM or Hz. If 0-02 Motor
Speed Unit is set to RPM: The speed limit parameters
4-11 Motor Speed Low Limit [RPM] and 4-13 Motor Speed
High Limit [RPM] limit the actual frequency converter
output. If 0-02 Motor Speed Unit set to Hz: The speed limit
parameters 4-12 Motor Speed Low Limit [Hz] and 4-14 Motor
MCA 123 POWERLINK Operating Instructions
Speed High Limit [Hz] limit the actual frequency converter
output.
4-19 Max Output Frequency limits the maximum output and
can also influence the maximum speed of the motor.
For reference and MAV formats, see Table 5.3.
Table 5.3 Reference and MAV Formats
NOTE
Negative numbers are formed as a complement of two.
NOTE
The data type for MRV and MAV is 16-bit standardised
value, which can express a range from -200% to +200%
(8001 to 7FFF).
1-00 Configuration Mode set to [0] Speed open loop.
3-00 Reference Range set to [0] Min - Max.
3-02 Minimum Reference set to 100 RPM.
3-03 Maximum Reference set to 3000 RPM.
0%
25%
50%
75%
100%
Table 5.4
5.2.4 Process Control Operation
In process control operation 1-00 Configuration Mode is set
to [3] Process.
The reference range in 3-00 Reference Range is always [0]
Min-Max.
- MRV represents the process setpoint.
- MAV expresses the actual process feedback (range
±200%).
®
MG92C102 - VLT
is a registered Danfoss trademark
MRV/MAV
Integer in hex
100%
4000
75%
3000
50%
2000
25%
1000
0%
0
-25%
F000
-50%
E000
-75%
D000
-100%
C000
MRV/MAV
0 hex
1000 hex
2000 hex
3000 hex
4000 hex
Integer in decimal
16.384
12.288
8.192
4.096
0
5
-4.096
-8.192
-12.288
-16.384
Actual speed
100 RPM
825 RPM
1550 RPM
2275 RPM
3000 RPM
15
5
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