R1: Reference point approach
15.7 Referencing by means of actual value adjustment
Basic Functions
1230
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Parameter assignment
The following machine data must be parameterized for actual value adjustment to a referenced measuring
system:
• Homing mode: Actual value adjustment to a referenced measuring system
MD34200 $MA_ENC_REFP_MODE[
measuring system
] = 6
• Traverse path for backlash recovery:
MD34080 $MA_REFP_MOVE_DIST[
measuring system
] (reference point distance)
15.7.3
Actual value adjustment for measuring systems with distance-coded reference
marks
Function
In order to improve positioning precision by determining the measuring-system-specific encoder fine information,
we recommend explicitly re-referencing the measuring system previously referenced by actual value adjustment
after switching over the measuring system.
If an encoder with distance-coded reference marks is used for the passive measuring system, referencing can be
avoided if the following conditions are met:
1. Active measuring system: indirect measuring system (motor measuring system) with absolute encoder, for
example
2. Passive measuring system: Direct measuring system with distancecoded reference marks
3. Travel movement of the machine axis with the referenced indirect measuring system before measuring
system switchover in which the number of reference marks required for referencing are crossed. This
automatically references the passive direct measuring system.
Note
Reference point distance greater than zero
To ensure reliable backlash recovery, the assigned value for the reference point distance
must be greater than the maximum backlash of both measuring systems.
Reference point distance equal to zero
The reference point distance can also equal zero. In this case, actual value adjustment is
performed without a traversing movement as soon as reference point approach starts. In
this case, the active backlash should be less than half the increment of the measuring
system whose actual value is taken.
