Parker PDHX-E Series User Manual page 47

senses the movement of material passing through the rollers via a drive wheel, as shown in
Figure 5-4. If slippage occurs driving the required length of material through the rollers the
encoder count will disagree with the motor step count, therefore Position Maintenance can be
used to give the motor more steps until the correct encoder count is achieved.
Stepper
Motor
Figure 5-4. Position Maintenance Used to Correct for Slippage
Stall Detect
Once an encoder is fitted to the motor, Stall Detection can be used. A stall occurs when the
error between the commanded position and the actual position, determined by the encoder,
exceeds the value set in the maximum allowable position error (CPE) command. The value
of CPE will be in motor steps and should not be set less than 40 steps in 4000 step/rev
mode. This is to allow for rotor lead/lag during acceleration and deceleration. If the motor
becomes desynchronised, the minimum resulting error will be 80 steps in 4000 step/rev
mode.
Stop-on-stall
You can enable the Stop-on-stall function with the FSD1 command. The move will terminate,
without any delay, as soon as the stall is detected. The function can be used in Motor Step
or Encoder Step mode.
Output-on-stall
A drive output can be defined to act as an Output-on-stall by assigning it the letter L. When a
stall condition occurs the output will be activated, but it will not latch the stall condition. By
selecting an output as an output-on-stall you are not causing the motor to stop on a stall.
The motor will not stop on a stall unless you enable it with an FSD1 command.
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Encoder
Signals to PLC
Start
Move
Complete
PDHX
Drive