Description

Task

Motions are generated by electronic probe systems or sensors. These motions should superimpose the programmed positions of axes when an NC program is interpolated.

This control helps to implement

distance control (e.g. contact with the curved surface of a plate) or
height control (e.g. to compensate for workpiece thickness tolerances).

Specifying the ideal workpiece surface for height control

Specifying the distance to workpiece for height control

Characteristics

A second measuring system is connected to the control system via an encoder. This measuring system can output axis-specific compensation values to an axis in addition to the interpolated command point to correct the actual position of the axis.

Distance control is enabled and disabled in the

NC program or
via the SPS.

Variables relevant to distance control can be parameterised via the axis machine data.

Distance control operates in the interpolation cycle of the control system (GEO task).

Notice

Distance control is only available for SERCOS, PROFIdrive or CANopen drives.

Parameterisation overview

The motion generated by distance control can be influenced by machine data.

Activating a mean value or a low pass filter
Maximum permissible correction value
Maximum additive axis velocity
Maximum permissible actual value jump of the probe system
Maximum upper axis position
Minimum lower axis position
Tolerance value
Dynamic weighting dependent on distance
(as of CNC Build V2.11.2804.02)
Dynamic weighting dependent on lowering movement(as of CNC Build V2.11.2807.13)

Enable/disable is executed either by the NC program or the PLC.

Structure of distance control in conjunction with other compensations

Correction of set position

The actual workpiece surface produces a height offset:

where

This results in a correction of the programmed command position Pos_Cmdof the tool as follows:

Configuration overview

The encoder of the electronic probe system is connected to the controlled axis as actual value encoder 2. Make sure that the first configured encoder is used for axis position control and the second encoder for distance control. Encoder for distance control.

Attention

The axis-specific feed override and the axis-specific feedhold enable act on distance control (see [HLI// Control commands of an axis]).

When override is 0 or when feedhold is set, distance control is no longer active and the current value is frozen.