Rockwell Automation 7000 PowerFlex Medium Voltage AC Drive (B Frame) - ForGe Control - Manual (Page 154)

154 Rockwell Automation Publication 7000-UM202B-EN-P - June 2014
Chapter 3 Component Definition and Maintenance
20B-ENC-1 & 20B-ENC-1-MX3 Encoder Interface
This encoder interface enables connecting the drive to a standard Quadrature
Encoder. The 20B-ENC encoder interface provides three optically isolated
differential encoder inputs for A and B phases as well as a Z track. You cannot
configure these inputs for use with a single ended encoder. The board only
supports differential encoders. The board also provides a galvanically isolated
12V/3 W supply to power the attached encoder. You can configure the 20B-
ENC-1 Encoder interface for 5V operation, however Rockwell Automation
recommends operation at 12V.
Figure 137 - Encoder Interface (20B-ENC-1 and 20B-ENC-1-MX3)
Operation at 5V does not support long cable lengths, given the need to regulate
power within 5% at the encoder. Cable resistance and capacitance makes it
difficult to regulate power at the encoder to 4.75V. Longer cables may decrease
voltage below 4.75V, causing encoder malfunction. As a general rule, using
18 Avg cabling with an Rdc of 19.3 Ω/km limits the cable length to 12 m (42 ft)
from the board to the encoder.
The 20B-ENC-1-MX3 encoder option is functionally identical to the 20B-
ENC-1 encoder with the addition of conformal coating.
J3
J3
J2
+1 2V
1 2 3
12
11
21
+5 VR EF
1 2 3
+5V
+12V
1 2 3 +12V
+5V
12
11
21
12
11
21
J2
NOTE: Must be configured for
12V operation
Output
Config.
Input
Config.