Rockwell Automation 20-COMM-R Remote I/O Adapter User Manual
Page 41
Using Discrete and Block Transfer I/O
4-5
20-COMM-R Remote I/O Adapter User Manual
Publication 20COMM-UM004D-EN-P
PowerFlex 70/700/700H, and PowerFlex 700L Drives with 700 Control
The Reference/Feedback value is a scaled engineering value; it is not in Hertz
or RPM. The Reference uses a ‘32767’ scale. The ‘32767’ endpoint of the
scale is equal to the value of drive parameter 55 - [Maximum Freq], which
has a default value of 130 Hz. For these drives, default scaling is 0…15123
which is equal to 0…60.0 Hz. This is based on the formula shown below.
Reference/Feedback scaling is limited by drive parameter 82 - [Maximum
Speed]. If the default value of 60 Hz. for parameter 82 - [Maximum Speed] is
changed, the speed Reference/Feedback scaling also changes. To determine
Reference/Feedback scaling, use the following formula:
(Parameter 82 ÷ Parameter 55) * 32767 = Scaling
Using drive parameter 82 and 55 default values, speed Reference/Feedback
scaling is:
(60 Hz ÷ 130 Hz) * 32767 = 15123
Therefore, 0…15123 = 0…60.0 Hz.
If parameter 82 - [Maximum Speed] is changed to 90 Hz, then:
(90 Hz ÷ 130 Hz) * 32767 = 22685
Therefore, 0…22685 = 0…90.0 Hz.
A graphic representation of this Reference/Feedback scaling is shown below.
For PowerFlex 70 drives with enhanced control, firmware 2.xxx or later, or
PowerFlex 700 drives with vector control, firmware 3.xxx or later, drive
parameter 298 - [DPI Ref Select] was added to simplify scaling for the
speed Reference/Feedback. When drive parameter 298 - [DPI Ref Select] is
set to its default ‘0’ (Max Freq), the speed Reference/Feedback scaling is as
shown above. However, when parameter 298 - [DPI Ref Select] is set to ‘1’
(Max Speed), the speed Reference/Feedback scaling is equal to parameter
82 - [Max Speed]:
Parameter 82 = Scaling
Using the parameter 82 default value, speed Reference/Feedback scaling is:
0…32767 = 0…60.0 Hz.
Size
Valid Values
16-bit
-32768 to 32767
32-bit
-2147483648 to 2147483647
0
0 Hz
Par
. 55 - [Maxim
um F
req]
Par. 82 - [Maxim
um Speed]
130 Hz
90 Hz
60 Hz
32767
22685
15123
Scaling = (Parameter 82 ÷ Parameter 55) * 32767