Rockwell Automation Publication 520-UM001G-EN-E - September 2014 203
Appendix E
Encoder/Pulse Train Usage and Position
StepLogic Application
Encoder and Pulse Train
Usage
The PowerFlex 520-series drives include a pulse train input built into the
terminal block. PowerFlex 525 drives also support an optional encoder card. The
pulse train and encoder can be used for many of the same functions, but the pulse
train supports up to 100 kHz at 24V, and uses the drive built-in terminal block.
The encoder supports up to 250 kHz dual channel at 5, 12 or 24V and requires
the optional encoder board to be installed. When A535
[Motor Fdbk Type] is set
to a value other than zero, the drive is set to use an encoder or pulse train. The
drive will use the encoder or pulse train in several ways depending on the settings
of other parameters. The drive will use the encoder or pulse train as shown below
(listed in order of priority):
1. If enabled by P047
, P049, or P051 [Speed Referencex], the encoder or
pulse train will be used directly as a commanded speed (normally used
with a pulse train) or as a position reference (normally used with a
quadrature encoder).
2. If not enabled by the Speed Reference parameters, the encoder or pulse
train can be used with the PID function if enabled by A459
or A471 [PID
x Ref Sel], or A460
or A472 [PID x Fdback Sel].
3. If not enabled by the Speed Reference or PID function parameters, the
encoder or pulse train can be used with A535
[Motor Fdbk Type] for
direct feedback and trim of the speed command. The normal slip
compensation is not used in this case. Instead the drive will use the encoder
or pulse train to determine actual output frequency and adjust the output
frequency to match the command. Parameters A538
[Ki Speed Loop] and
A539
[Kp Speed Loop] are used in this control loop. The primary benefit
of this mode is increased speed accuracy when compared to open-loop slip
compensation. It does not provide speed bandwidth improvement.
Encoder Interface
The incremental encoder option card can source 5 or 12 volt power and accept 5,
12 or 24 volt single ended or differential inputs. See Appendix B
for ordering
information.
The encoder usage, and position StepLogic application covered in this chapter
is specific to PowerFlex 525 drives only.
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