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Homing

Homing serves to establish an absolute position reference (referred to the entire axis), and must usually be performed once after power-up. Homing is necessary when absolute positioning operations are carried out without absolute value encoders (e.g. SSI multiturn encoders). For all other positioning operations (relative, infinite) no homing is required. For zero position adjustment of absolute encoders homing method -5 is available. There are various methods, which can be set according to the application.

The selection of a homing method defines:

• the reference signal (positive limit switch, negative limit switch, reference cam)
• the direction of the drive
• the position of the zero pulse.
  
  
  

Homing dialog box

The homing movement is dictated by the speed (velocity) V1 and V2, the acceleration and the maximum positioning range.

Bild: Selection of homing method

Number	Meaning
	Selection of homing methods (-12) to (35)
	Speed V1: Speed during cam search Speed V2: Speed during zero point search
	Acceleration for V1 and V2
	The reference point usually has an actual position value defined on the axis side referred to the axis zero. Ideally, the position value of the drive-side datum point and of the reference point are identical. As the position of the datum point is decisively influenced by the encoder mounting, however, the datum and reference points differ. To establish a positional reference to the real axis zero, the desired axis-related actual position value of the reference point should be set via the zero offset.
	Limitation of positioning range for homing. On exiting the positioning range, the axis is stopped with the error message "Overrun".

Tabelle: Description of dialog box

NOTE: The reference cam signal is optionally linked to one of the digital inputs. Fast inputs ISD05 and ISD06 are available.

Homing to a limit switch:

The digital input must be set to the available selection parameter LCW(5) for a positive limit switch or to LCCW(6) for a negative limit switch.

Homing to a cam:

Set digital input to HOMSW(10) (parameters P 0106 MPRO_INPUT_FS_ISD06 to P 0107 MPRO_INPUT_FS_ISD07).

NOTE: Homing methods (-1) to (-12) are manufacturer-specific. Homing methods (0) to (35) are defined according to CiA402.