Lenze 8400 motec - Manual (Page 238)

7 Technology applications
7.4 TA "Switch-off positioning"
238 Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05
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7.4 TA "Switch-off positioning"
This function extension is available from version 05.00.00!
The basic principle of this technology application is to travel to a switch-off sensor (e.g. a limit
switch) in a speed-controlled manner and to stop as close as possible at this position. Unlike other
positioning controls, the switch-off positioning neither has a position feedback nor calculates the
path in advance. Thus, the accuracy that can be achieved depends on various factors such as the
speed at which the switch-off sensor is advanced.
In addition, a pre-switch off can be implemented which requires a sufficient number of unassigned
digital inputs on the controller which can be used to connect other sensors for the additional stop
positions. These sensors effect a reduction in speed before the last switch-off sensor is reached.
Features
• Pre-configured control modes for terminals and bus control (with predefined process data
connection to the fieldbus)
• Free configuration of input and output signals
• Offset and gain of the main setpoint (if defined via analog input)
• Up to 3 fixed setpoint for speed
• Adjustable setpoint ramp times
• Linear or S-shaped ramp type
• Automatic holding brake control
• Quick stop (QSP) with adjustable ramp time
• Load monitoring
• Implemented and freely available "GeneralPurpose" functions:
Counter, binary delay element, binary logic, analog comparison
• Integration of encoder feedback
• Switch-off sensor management for the implementation of a pre-switch off
Decision criteria
Criteria Switch-off positioning with constant
load
Switch-off positioning with variable
load
Operating mode V/f characteristic without speed sensor.
Alternatively for large breakaway torques: Use of a sensorless vector control
(only applicable for horizontal movements).
Limit switch evaluation One limit switch is required per
direction of movement.
When the limit switch is reached, the
drive is brought to a standstill leaded
by the deceleration ramp or the QSP
ramp.
One limit switch and an initiator for
quick/slow switch-over is required
per direction of movement.
When the initiator is reached, the
speed of the drive is reduced to
creeping speed (fixed setpoint 2) in a
controlled way.
When the limit switch is reached, the
drive is brought to a standstill leaded
by the deceleration ramp or the QSP
ramp.