Siemens SINUMERIK 840Di Function Manual page 1455

Setting notes
• Reference cam
• Electronic reference cam offset
Phase 2: Features
• Feedrate override is not active.
• The feed stop (channel-specific and axis-specific) is active.
• NC-STOP and NC-START are not active.
• If in Phase 2 the machine axis does not reach the reference mark (encoder zero mark)
Reference Point Approach (R1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Aligning the signal edge of the reference cam directly between two zero marks has
proven to be the most practical method.
Information needed for parameterizing the electronic reference cam offset is to be found
in the read-only machine data:
MD34093 $MA_REFP_CAM_MARKER_DIST (distance between reference cam/reference
mark)
The indicated value is equivalent to the distance between departure from the reference
cam and detection of the reference mark. If the values are too small, there is a risk that
the determination of the reference point will be nondeterministic, due to temperature
effects or fluctuations in the operating time of the cam signal.
Warning
If the reference cam adjustment is faulty or inaccurate, an incorrect zero mark can be
evaluated. The control then calculates an incorrect machine zero. As a result, the
machine axis will approach the wrong positions. Software limit switches, protected areas
and working area limitations act on incorrect positions and are therefore incapable of
protecting the machine. The path difference is +/- of the path covered by the machine
axis between 2 zero marks.
Internal motion with feedrate override = 100%.
If a feedrate override of 0% is specified, motion is aborted.
within the assigned distance:
MD34060 $MA_REFP_MAX_ MARKER_DIST (maximum distance to reference mark)
the machine axis is stopped.
2.4 Referencing with incremental measurement systems
Detailed Description
2-15