Unbuffered encoder outputs, Incremental encoder outputs – Rockwell Automation 2090 Ultra3000 Servo Drives Integration Manual User Manual
Page 138
Publication 2098-IN005C-EN-P — March 2008
138
Understanding Motor Feedback Signals and Outputs
Unbuffered Encoder
Outputs
The unbuffered outputs available from the drive (CN1-10 through
CN1-15) are tied directly to the incoming (incremental or high
resolution) encoder signals (CN2-1 through CN2-6). The unbuffered
outputs are not filtered or conditioned.
Incremental Encoder
Outputs
Incremental encoder counts are generated in the drive by counting the
(high to low and low to high) transitions of the incoming A and B
encoder signals. In the channel A signal has two transitions, as does
the channel B signal, which results in x4 interpolation (4 transitions/
line equals 4 counts/line). For example, typical 2000 line/rev encoder
output becomes 8000 counts/rev in the drive. Counts are not directly
available at the encoder outputs, only the A quad B representation.
Incremental Encoder Counts
The incremental buffered outputs (listed below) are available from the
drive (CN1-16 through CN1-21) and software selectable.
•
Buffered Outputs are a filtered representation of the original
incoming encoder (CN2) signals. Buffered outputs have the same
number of cycles/rev as found on CN2.
•
Interpolated Outputs are the same as buffered outputs when
using an incremental encoder. The only interpolation performed
on an A quad B signal is the drive’s internal counting of transitions
(4 counts/line). Because counts are not available outside the drive,
selecting this in software is the same as selecting buffered (as
described above).
•
Divided Outputs are the same as buffered outputs, except when
divided is selected in the software, the lines/rev are then reduced
by the value of the divisor chosen in the software (as shown in the
figure below).
Incremental Encoder Divided
One Cycle
Channel A
Channel B
Counts
B
A
CW
CN2-1
CN1-10
CN1-16
Signal A+ from Incremental Encoder
Unbuffered Signal A+ Output from Drive
Divided (by two) Signal A+ Buffered Output from Drive