Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 154)

Scale Blocks
154 Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Scale Blocks
See also Analog Scaling on page 22 and page 32 .
Scale blocks are used to scale a parameter value. [Scalex In Value] is
linked to the parameter that you wish to scale. [Scalex In Hi] determines the high
value for the input to the scale block. [Scalex Out Hi] determines the
corresponding high value for the output of the scale block. [Scalex In Lo]
determines the low value for the input to the scale block. [Scalex Out Lo]
determines the corresponding low value for the output of the scale block. [Scalex
Out Value] is the resulting output of the scale block.
There are (3) ways to use the output of the scale block:
1. A linkable destination parameter can be linked to [Scalex Out Value]. See
Example Configuration #1 .
2. [Analog Outx Sel] can be set to:
– 20, “Scale Block1”
– 21, “Scale Block2”
– 22, “Scale Block3”
– 23, “Scale Block4”
Note that when the Analog Outputs are set to use the scale blocks, the [Scale x
Out Hi] and [Scale x Out Lo] parameters are not active. Instead, [Analog
Outx Hi] and [Analog Outx Lo] determine the scaling for the output of the
scale block. See
Example Configuration #2 .
3. [PI Reference Sel] and [PI Feedback Sel] can also use the output of the scale
block by setting them to:
– 25, “Scale Block1 Out”
– 26, “Scale Block2 Out”
Note that when [PI Reference Sel] and [PI Feedback Sel] are set to use the
scale blocks, the [Scale x Out Hi] and [Scale x Out Lo] parameters are not
active. Instead, [PI Reference Hi] and [PI Reference Lo], or [PI Feedback Hi]
and [PI Feedback Lo], determine the scaling for the output of the scale block.
See
Example Configuration #3 .
Example Configuration #1
Use the scale blocks to add a speed trim as a percentage of the speed reference
instead of as a percent of full speed. Analog In 2 will be used to provide a 0-10V
DC trim signal. For example, when the commanded speed is 800 RPM, the
maximum trim with 10V DC at Analog In 2 will be 80 RPM. If the commanded
speed is 1800 RPM the maximum trim will be 180 RPM.
Vector
Cmd Spd = 400 RPM
Cmd Spd =
800 RPM
Cmd Spd = 1200 RPM
Cmd Spd = 1
800 RPM
0
0
2
4
6
8
10
20 40 60 80 100 120 140 180
Preset Speed 1 (RPM)
Scale1 In Value =
Analog In2 Val (Volts)