ABB ACS880 N5700 Series, Руководство по прошивке, Страница: 39 / 662

Position feedback can be configured to come from encoder 1, encoder 2, or an
estimate. The configuration is done in parameter groups 90…93.
The actual position can be set to a predefined value using these methods:
• “Set position” command ( 74.24 ). The new value is defined by 75.35 and 75.36 .
• Configuration of actual position after power-up ( 86.69 ).
• Configuration of actual position after homing sequence ( 86.30 ). See section
Homing (page 46) .
Actual position in linear movement can be limited by software and hardware limits.
See section Position limits (page 45) .
￭ Position calculation
The actual position of the drive is measured using a position feedback device.
During normal operation, the actual position is measured by keeping track of the
change in position between the last known position and the current time. The
position calculation is non-saturating: after the upper boundary of the range has
been reached, the value rolls over to the maximum negative value (or zero if modulo
range is being used).
The actual measured position is shown by these parameters:
• Encoder 1 (revolutions): 90.11 … 90.13
• Encoder 1 (raw position, 1 revolution = 224): 90.14 … 90.15
• Encoder 2 (revolutions): 90.21 … 90.23
• Encoder 2 (raw position, 1 revolution = 224): 90.24 … 90.25
The resolution used for position control calculation is defined by parameters. It
is recommended to use the native resolution of the feedback device, but other
values can also be used.
• 86.11 Enc1 increments per revolution
• 86.12 Enc2 increments per revolution
The actual encoder position in increments (based on the resolution settings) is
shown by these parameters:
• 86.4 Encoder 1 position
• 86.5 Encoder 2 position
• 86.6 Estimated position
Actual position for the control is selected by parameter 86.13 , and shown as a raw
value (increments according to the defined resolution) and as a scaled value (units).
• 86.8 Actual position raw
Position control program features 39