6.2.3 Reference Handling
The reference handling in FC 301/FC 302 is an advanced
mechanism that sums up references from different sources.
For more information on reference handling, refer to the
FC 301/FC 302 Design Guide
.
Illustration 6.2
The reference, or speed set point (MRV, sent via EtherCAT),
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 6.3
NOTE
If
3-00 Reference Range
is set to
[0] Min - Max
, a negative
reference is handled as 0%.
The speed limit parameters in
4-11 Motor Speed Low Limit
[RPM]
to
4-14 Motor Speed High Limit [Hz]
limits the actual
frequency converter output.
4-19 Max Output Frequency
sets the final speed limit.
The reference and the MAV have the format which appears
from
.
MRV/MAV
Integer in hex
Integer in decimal
100%
4000
16.384
75%
3000
12.288
50%
2000
8.192
25%
1000
4.096
0%
0
0
-25%
F000
-4.096
-50%
E000
-8.192
-75%
D000
-12.288
-100%
C000
-16.384
Table 6.3 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.
MRV/MAV
Actual Speed
0%
0 hex
100 RPM
25%
1000 hex
825 RPM
50%
2000 hex
1550 RPM
75%
3000 hex
2275 RPM
100%
4000 hex
3000 RPM
Table 6.4
6.2.4 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%).
How to Control the Frequenc...
MCA 124 EtherCAT Operating Instruction
16
MG92A302 - VLT
®
is a registered Danfoss trademark
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