Siemens SINAMICS S150 NEMA, Operating Instructions Manual

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Functions, monitoring and protective functions
9.3 Drive functions
Enclosed Drives
604
Operating Instructions, 12/2018, A5E36652151A
The encoder position actual value in r0483 (must be requested via GnSTW.13) is limited to
2
32
places. When position tracking (p0411.0 = 0) is deactivated, the encoder actual position
value r0483 comprises the following position information:
● Encoder pulses per revolution (p0408)
● Fine resolution per revolution (p0419)
● Number of resolvable revolutions of the rotary absolute encoder (p0421), this value is
fixed at "1" for singleturn encoders.
When position tracking (p0411.0 = 1) is activated, the encoder actual position value r0483 is
composed as follows:
● Encoder pulses per revolution (p0408)
● Fine resolution per revolution (p0419)
● Virtual number of resolvable motor revolutions of a rotary absolute encoder (p0412)
If the measuring gear is absent (n=1), the actual number of the stored revolutions of a
rotary absolute encoder p0421 is used. The position area can be extended by increasing
this value.
If the measuring gear is available, this value equals the number of resolvable motor
revolutions, which is stored in r0483.
● Gearbox ratio (p0433/p0432)
9.3.26.2 Measuring gearbox
Description
If a mechanical gear (measuring gear) is located between an endlessly rotating motor or load
and the encoder and position control is to be carried out using this absolute encoder, an
offset occurs (depending on the gear ratio) between the zero position of the encoder and the
motor or load whenever encoder overflow occurs.
Figure 9-16 Measuring gearbox
In order to determine the position at the motor or load, in addition to the position actual value
of the absolute encoder, it is also necessary to have the number of overflows of the absolute
encoder.
If the power supply of the control module must be powered-down, then the number of
overflows must be saved in a non-volatile memory so that after powering-up the position of
the load can be uniquely and clearly determined.