Position Tracking With A Measuring Gearbox - Siemens SINAMICS S120 Function Manual

Hide thumbs Also See for SINAMICS S120:

Table of Contents

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)

Position tracking with a measuring gearbox

● Using an absolute encoder

Function description

If a mechanical gear (measuring gear) is located between an endlessly rotating motor or load

and the encoder and position control is 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.

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

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.

Gear ratio 1:3 (motor revolutions p0433 to encoder revolutions p0432), absolute encoder can

count eight encoder revolutions (p0421 = 8).

Drive functions

Function Manual, 06/2019, 6SL3097-5AB00-0BP2

Measuring gearbox

Basic functions

8.23 Position tracking