Siemens Sinumerik 801 Technical Manual page 49

BERO sampling methods
V
Threshold Level
Rising Edge
Ref. Point
Fig. 2-27 BERO sampling methods
Mechanical installation of the proximity switches
SINUMERIK 801
Start-Up
Single-switch mode (without reference cam, MD34000=0)：
There is one BERO in the axis.
Machine body
Leadscrew
Fig. 2-26 Configuration 2 for reference point approaching: single-switch mode
With this mode, only one speed for referece point approaching can be set.
Precision of reference point approach is relevant to the quality of BERO and
the speed set for approaching reference points.
No matter which configuration is taken, the control system can use two ways
to sample BERO when approaching the reference point:
1) Sample the rising edge of BERO and take the effective level of the rising
edge as the reference mark;
2) Move the axis onwards, record the distance traversed after this
reference mark and sample the falling edge of BERO. After samping the
falling edge, the control system will auto-calculate the middle point
between both edges and use this point as the reference point for the
axis.
Falling Edge
Follow Fig. 2-28 & 2-29 to complete the mechanical installation of BERO under
double-switch mode.
When stepper motors is connected with a leadscrew directly:
Signal output to X20
V
Threshold Level
Threshold Level
t
Start-Up
Object under test
Bero
Falling Edge
Ref. Point
t
2-33