Reference Limits - Danfoss VLT Midi Drive FC 280 Design Manual

Product Overview
The remote reference is calculated once in every scan
interval and initially consists of 2 types of reference
inputs:
2 2
1. X (the external reference): A sum (see
parameter 3-04 Reference Function) of up to 4
externally selected references, comprising any
combination (determined by the setting of
parameter 3-15 Reference 1 Source,
parameter 3-16 Reference 2 Source, and
parameter 3-17 Reference 3 Source) of a fixed
preset reference (parameter 3-10 Preset Reference),
variable analog references, variable digital pulse
references, and various fieldbus references in any
unit the frequency converter is monitoring ([Hz],
[RPM], [Nm], and so on).
2. Y (the relative reference): A sum of 1 fixed preset
reference (parameter 3-14 Preset Relative Reference)
and 1 variable analog reference
(parameter 3-18 Relative Scaling Reference
Resource) in [%].
The 2 types of reference inputs are combined in the
following formula:
Remote reference=X+X*Y/100%.
If relative reference is not used, set parameter 3-18 Relative
Scaling Reference Resource to [0] No function and
parameter 3-14 Preset Relative Reference to 0%. The digital
inputs on the frequency converter can activate both the
catch up/slow down function and the freeze reference
function. The functions and parameters are described in
®
the VLT Midi Drive FC 280 Programming Guide.
The scaling of analog references is described in parameter
groups 6-1* Analog Input 53 and 6-2* Analog Input 54, and
the scaling of digital pulse references is described in
parameter group 5-5* Pulse Input.
Reference limits and ranges are set in parameter group 3-0*

Reference Limits.

22
®
VLT Midi Drive FC 280
2.4.1 Reference Limits
Parameter 3-00 Reference Range, parameter 3-02 Minimum
Reference, and parameter 3-03 Maximum Reference define
the allowed range of the sum of all references. The sum of
all references is clamped when necessary. The relation
between the resulting reference (after clamping) and the
sum of all references are shown in Illustration 2.14 and
Illustration 2.15.
P 3-00 Reference Range= [0] Min-Max
P 3-03
P 3-02
-P 3-02
-P 3-03
Illustration 2.14 Sum of All References When Reference Range
is Set to 0
P 3-03
-P 3-03
Illustration 2.15 Sum of All References When Reference Range
is Set to 1
The value of parameter 3-02 Minimum Reference cannot be
set to less than 0, unless parameter 1-00 Configuration
Mode is set to [3] Process. In that case, the following
relations between the resulting reference (after clamping)
and the sum of all references are as shown in
Illustration 2.16.
Danfoss A/S © 03/2016 All rights reserved.
Resulting reference
Forward
Reverse
P 3-00 Reference Range =[1]-Max-Max
Resulting reference
Sum of all
references
Sum of all
references
MG07B102