Rockwell Automation 20P PowerFlex Digital DC Drive - Manual (Page 286)

286 Rockwell Automation Publication 20P-UM001I-EN-P - February 2013
Appendix C Application Notes
Scale Blocks The Scale Blocks function allows you to link or rescale dissimilar parameter types
(for example, integer vs. real) though multiply, divide, maximum and minimum
limits, input and output offsets and absolute value functions. There are six
individually configurable Scale Blocks. A representative block diagram is shown
below.
The following rules apply to Scale Blocks:
• All input [Scalex Input] and output [Scalex Output] values are specified as
a parameter number (not parameter values).
• Both Sink (read/write) and Source (read only) parameters can be used as
input values ([Scalex Input]).
• Only Sink (read/write) parameters can be used as the output value ([Scalex
Output]).
• Configuration parameters (parameters that can only be changed while the
drive is stopped) can be used as the output value ([Scalex Output]).
However, any value written to a configuration parameter will not take
effect in the drive until it is stopped.
• The output value is truncated to a whole number when different
parameter types are used (for example, a real input value of 54.97%
becomes an integer output value of 54 rpm).
• Dividing by zero (0) does not cause an error, but will result in an output
value of zero (0).
• Turning off (setting = “0”) the input parameter or changing the output
parameter number does not reset or change the original output value (i.e.,
the output parameter remains at the last value written).
IMPORTANT The Scale Blocks functions are executed sequentially in the background, which
can cause a delay in processing data between the input and output values. The
amount of delay is dependant on the application.
Σ
+
+
X
+
+
Scale Block 1
P484
Scale1 Input
P492
Scale1 In Abs
P490
Scale1 In Off
P489
Scale1 In Min
P488
Scale1 In Max
P486
Scale1 Mul
P487
Scale1 Div
P491
Scale1 Out Off
P485
Scale1 Output Σ