Reference Handling - Danfoss VLT AutomationDrive FC 300 Design Manual

3. Introduction to FC 300
The reference handling system for calculating the Remote reference is shown in the illustration
below.
3
The Remote reference is calculated once every scan interval and initially consists of
two parts:
1.
2.
The two parts are combined in the following calculation: Remote reference = X + X * Y / 100%.
The
digital inputs on the frequency converter. They are described in par. group 5-1*.
The scaling of analog references are described in par. groups 6-1* and 6-2*, and the scaling of
digital pulse references are described in par. group 5-5*.
Reference limits and ranges are set in par. group 3-0*.

3.2.9. Reference Handling

References and feedback can be scaled in physical units (i.e. RPM, Hz, °C) or simply in % relating
to the values of par. 3-02
26
X (the external reference) : A sum (see par. 3-04) of up to four externally selected ref-
erences, comprising any combination (determined by the setting of par. 3-15, 3-16 and
3-17) of a fixed preset reference (par. 3-10), variable analog references, variable digital
pulse references, and various serial bus references in whatever unit the frequency con-
verter is controlled ([Hz], [RPM], [Nm] etc.).
Y- (the relative reference): A sum of one fixed preset reference (par. 3-14) and one
variable analog reference (par. 3-18) in [%].
catch up / slow down
function and the
Minimum Reference
MG.33.B9.02 - VLT
freeze reference
function can both be activated by
Maximum Reference
and par. 3-03
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FC 300 Design Guide
.