Homing; Overview Of Homing; One Time Homing Methods - Danfoss iC7 Motion Series Application Manual

Application Guide | iC7 Series Motion

Homing

2.12.4

Overview of Homing

2.12.4.1
The Homing function is used to define the zero point of the machine, thus creating a relation between the physical position of the
machine and position values registered by the drive. Homing is needed in different situations depending on operating mode and type of
feedback.
With sensorless operation, homing is needed after power-up and when the motor is moved while not controlled by the drive; after a
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fault, for example.
With incremental feedback, homing is needed after power-up.
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With absolute feedback, homing can be used during commissioning to define an offset for the absolute positions received from the
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encoder, as an alternative to physically aligning the encoder with the machine position.
The Homing on the fly function refreshes the home position while the drive is running, without affecting the ongoing movement. It
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can be used to avoid position drifting especially for asynchronous motors in sensorless operation.

One Time Homing Methods

2.12.4.2
The drive supports several different homing methods, selectable with parameter 5.17.2.3 Home Mode:
Home Direct
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Home on Sensor
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Home on Block
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These homing functions are executed by the Home Enable signal, which must remain high until the selected homing function is
completed. If the Home Enable signal is removed before home is found, the ongoing homing movement is interrupted. The source for the
Home Enable signal is selected with parameter 5.17.2.1 Home Enable Input.
Note:
A prerequisite for any homing movement is that the drive is in positioning mode, is enabled, and has received a start
command.
It is possible to set time and distance limits for finding the home position with parameters 5.17.2.10 Home Time Limit and 5.17.2.11 Home
Distance Limit. A fault occurs if home is not found within the set time or distance.
Home Direct
Home Direct sets Actual Position and Demanded Position to the value of parameter 5.17.2.5 Home Position and the Home Done signal is set,
meaning there is no movement of the motor.
Home on Sensor
Home on Sensor performs a search for the home sensor connected to the input selected with parameter 5.17.2.2 Home Sensor Input, and
sets Actual Position to the value of parameter 5.17.2.5 Home Position at the edge of the home sensor signal. The home sensor can be a
separate sensor, or 1 of the Hardware End limits can be used as home sensor.
Speed, ramps, and the direction for home sensor search are configured by parameters 5.17.2.6 Home Speed, 5.17.2.8 Home Ramp Selection,
and 5.17.2.4 Home Search Direction.
A second home speed can be defined. It enables the drive to find the home sensor at a high speed set with parameter 5.17.2.6 Home
Speed, while doing the actual home sensor detection at a lower speed, for higher accuracy, set with parameter 5.17.2.7 Home Speed Low.
When parameter 5.17.2.7 Home Speed Low is set to zero (which is the default), the speed set with parameter 5.17.2.6 Home Speed is used
for the entire homing procedure.
The following illustrations show different scenarios with different positions defined as home:
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