Measuring Gear - Siemens SINAMICS S120 Function Manual

Basic functions
7.21 Position tracking
The encoder actual position value in r0483 (must be requested via GnSTW.13) is limited to
2
32
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)
7.21.2

Measuring gear

If a mechanical gear (measuring gear) is located between an endlessly rotating motor/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/load whenever encoder overflow occurs.
Figure 7-14
In order to determine the position at the motor/load, in addition to the actual position value of
the absolute encoder, it is also necessary to have the number of absolute encoder overflows.
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.
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places. When position tracking (p0411.0 = 0) is switched off, the encoder actual position
Measuring gearbox
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
Drive functions