Siemens SINAMICS S150 Operating Instructions Manual page 376

Functions, monitoring, and protective functions
9.4 Extended functions
Note
The velocity override is effective during the search for the cam. When the encoder data
set is changed, status signal r2684.11 (reference point set) should be reset.
The cam switch must be able to delivery both a rising and a falling edge.
During the search for reference when evaluating the sensor zero mark, the 0/1 edge is
evaluated with increasing actual position values and the 1/0 edge with falling actual
position values. Inversion of the edge evaluation is not possible at the sensor zero mark.
If the length measuring system has several zero marks which repeat at cyclic intervals
(e.g. incremental, rotary measuring system), you must ensure that the cam is adjusted so
that the same zero mark is always evaluated.
The following factors may impact on the characteristics of the "reference cam" control
signal:
• Switching accuracy and time delay of reference cam switch
• Position controller cycle of drive
• Interpolation cycle of drive
• Temperature sensitivity of machine's mechanical system
● Search for reference, step 2: Synchronization to reference zero mark (encoder zero mark
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or external zero mark)
Reference mark present (p2607 = 1):
In step 2, the drive accelerates to the velocity specified in p2608 (zero mark approach
velocity) in the direction opposite to that specified by binector input p2604 (search for
reference start direction). The zero mark is expected at distance p2609 (max. distance to
zero mark). The search for the zero mark is active (status bit r2684.0 = "1" (search for
reference active)) as soon as the drive leaves the cam (p2612 = "0") and is within the
tolerance band for evaluation (p2609 - p2610). If the position of the zero mark is known
(encoder evaluation), the actual position of the drive can be synchronized using the zero
mark.
The drive starts the search for reference (see step 3). The distance traveled between the
cam end and zero mark is displayed in parameter r2680 (difference between cam and
zero mark).
Encoder zero mark (p0495 = 0), no reference mark present (p2607 = 0):
Synchronization to the reference zero mark begins as soon as the signal at binector input
p2595 (start homing) is detected. The drive accelerates to the velocity specified in
parameter p2608 (zero mark approach velocity) in the direction specified by the signal of
the binector input p2604 (search for reference start direction).
The drive synchronizes to the first zero mark. The drive continues at the same speed and
travel to the reference point is started (see step 3).
Drive converter cabinet units
Operating Instructions, 07/07, A5E00288214A