# Phase 3: Move to reference cam with referencing

Parameterising Phase 3 | P-AXIS-00084 (homing_without_zero_pulse) | With or without zero pulse
| P-AXIS-00158 (ref_richt) | Referencing direction
| P-AXIS-00218 (vb_reflow) | Slow referencing velocity, e.g. 15000 [μm/s]

## Start of Phase 3

Phase 3 is started automatically if Phase 2 was completed successfully and the machine axis is no longer located on the reference cam.

The reference position can be searched by:

- the zero pulse or
- the reference cam.

## Referencing with zero pulse

Homing in 3 phases, referencing to the reference cam with zero pulse

## Referencing with reference cam

Homing in 3 phases, referencing to the reference cam with zero pulse

## Notice

With this parameterisation, reference is executed on the positive edge of the cam signal in Phase 3, i.e. during motion to the cam.

Referencing is executed when the cam switch is operated in the Phase 3 of the homing sequence. With this method, the referencing accuracy is defined by the axis velocity (vb_reflow) in Phase 3 and the sampling time since the position is only adopted at discrete times and the position value is not latched as with zero pulse evaluation.

This method is used in stepper motor applications without incremental encoder, for example. A generally acceptable accuracy is attainable here if P-AXIS-00218 (vb_reflow) is initialised so that the motor moves at one increment per sampling cycle in the 3rd phase.

This method is also used for “separable” drives (toothed rack, pinion) where the zero pulse signal is not normally used.