Referencing With Distance-Coded Reference Marks; General Overview - Siemens SINUMERIK 840D sl Function Manual

Special feature of Phase 3
In the following cases, the machine axis stops first after detection of the zero mark and then
traverses back to the reference point:
● Because of the reference point positioning velocity, the sum of reference point distance
and reference point offset is less than the required braking distance:
MD34080 + MD34090 < "required braking distance due to MD34070"
● The reference point is located, opposite to the current travel direction, "behind" the
reference cam.
MD34020 $MA_ REFP_VELO_SEARCH_CAM
(reference point approach velocity)
MD34040 $MA_REFP_VELO_SEARCH_MARKER
(reference point creep velocity)
Figure 15-11 Reference point distance plus reference point offset less than braking distance
15.6

Referencing with distance-coded reference marks

15.6.1

General overview

Distancecoded reference marks
Measuring systems with distance-coded reference marks consist of two parallel scale tracks:
● Incremental grating
● Reference mark track
The distance between any two consecutive reference marks is defined. This makes it possible
to determine the absolute position of the machine axis when two consecutive reference marks
are crossed. For example, if the distance between the reference marks is approx. 10 mm, a
traverse path of approx. 20 mm is all that is required to reference the machine axis.
Referencing can be performed from any axis position in the positive or negative direction
(exception: end of travel range).
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
15.6 Referencing with distance-coded reference marks
Velocity
MD34100 $MA_REFP_SET_POS [0 ... 3]
Reference cam
R1: Referencing
Distance
1167