Commanding and realization

Homing is commanded in each specific channel either by means of the "Homing" mode or by means of the NC command G74. This command can be executed either in a manual block or in a NC program.

During referencing, the axis assumes the reference position P-AXIS-00152 (pos_refpkt) from the axis parameter list and stops.

NC program

Homing is started either

Homing sequence of axes

The axes to be referenced and the sequence in which they are to perform homing can be specified with the NC command G74.

The values programmed with the axis names define the homing sequence. For axes with the same value, homing is triggered simultaneously (see also [PROG]).

Programming examples

Sequential commanding

In the following example, the axes Z, X, Y, A and B are commanded successively, i.e. Z has referenced before X begins with homing, etc.

N10 G74 Z1 X2 Y3 A4 B5

This mode may be necessary, for example, to first move the tool axis Z out of the collision zone with the workpiece or other axes. The other axes are then referenced.

Parallel commanding

In the following example, homing takes place in parallel (simultaneously) for the axes X, Y, A and B.

N10 G74 X1 Y1 A1 B1

This mode is suitable thanks to the shorter time required with low homing speed and a large travel range of the axis.

Another reason may be kinematic coupling of axes, which does not permit sequential homing.

Example

In the following example, the Z axis is referenced first and is moved to the safety level. Then, in the next NC block, the axes X and Y are commanded in parallel and then the axes A and B are also commanded in parallel. The spindle S is referenced last.

After homing has taken place, the axes can optionally be positioned by means of a travel command to any chosen position within the scope of the software limit switches. Any chosen initialization processes are also possible here.

NC program for homing 

%RPF.NC
N10 G74 Z1
(optional: Move Z on security hight)
N15 G01 G90 Z200 F500
N20 G74 X1 Y1 A2 B2 S3

(optional: Move axes on home positions)
N30 G01 X0 Y20 Z0 A90 F1000
N40 S.POS0 S500 M19
...
N40 M30

Drive-controlled homing

Homing executed independently by the drive itself is referred to as drive-controlled referencing. The NC controller orders the drive to reference its axis and, after homing has taken place, receives a confirmation from the drive about whether reference was successful. Homing is parameter-defined exclusively in the drive.

The CNC supports drive-controlled referencing of

Commanding and realization 1:

Apart from P-AXIS-00014, all homing parameters in the axis parameter list apply to NC-controlled referencing only.

NC-controlled homing

In the case of NC-controlled referencing, the entire sequence of homing is determined by the NC controller. Homing can be defined for each axis with the corresponding parameters in the axis parameter list. Depending on the homing strategy, it may be necessary to provide the reference cam signal on the HLI.

Supported drive types

NC-controlled referencing is supported for the following drive types:

Commanding and realization 2:

NC-controlled referencing is currently supported for drives with a SERCOS interface only without zero pulse search.

Drive simulation

The NC controller supports the "simulation" drive type, i.e. each axis can be simulated, for example if, within the scope of machine commissioning, there is still no physical drive (±10V, stepper motor, etc.) or if the control system is to be tested completely without physical drives. Homing can also be selected with this drive type. Referencing of these axes is simulated and be set by means of corresponding parameters in the axis parameter list.

Gantry coupling

In the case of gantry coupling, homing of the gantry slave axis can be suppressed with the P-AXIS-00074 parameter. After homing, the gantry master axis then assumes the reference position and monitoring of the gantry difference between the master and slave axes is started.

Otherwise, after referencing of the master axis, homing also takes place for the gantry slave axes. In both cases, the other mechanically coupled axis is controlled in synchronism.

See also