Efficient Networks Siemens Sinamics S120 - Manual (Page 211)

Basic functions
6.14 Position tracking
Drive Functions
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
211
Tolerance window (p0413)
After switching on, the difference between the stored position and the actual position is
ascertained and, depending on the result, the following is triggered:
Difference within the tolerance window -> the position is reproduced based on the current
actual encoder value.
Difference outside the tolerance window -> An appropriate message (F7449) is output.
The tolerance window is preset to quarter of the encoder range and can be changed.
NOTICE
The position can only be reproduced if, in the powered-down state, the encoder was moved
through less than half of the range that it can represent. For the standard EQN1325
encoder, this is 2048 revolutions or half a revolution for singleturn encoders.
Note
The ratio stamped on the gearbox type plate is often just a rounded-off value (e.g.1:7.34). If,
for a rotary axis, it is not permissible to have any long-term drift, then the actual ratio of the
gearbox teeth must be requested from the gearbox manufacturer.
Note regarding using synchronous motors with a measuring gearbox
Field-oriented control of synchronous motors requires a clear reference between the pole
position and encoder position. This reference must also be carefully maintained when using
measuring gearboxes: This is the reason that the ratio between the pole pair number and the
encoder revolutions must be an integer multiple ≥ 1 (e.g. pole pair number 17, measuring
gearbox 4.25, ratio = 4).
Commissioning
The position tracking of the measuring gearbox can be activated in the drive wizard
(STARTER) during the configuration of the drive. During the configuration there is an item for
encoder parameterization. In the encoder dialog, click on the "Details" button and activate
the checkbox for position tracking in the displayed dialog.
The parameters p412 (Measuring gearbox, rotary absolute encoder, revolutions, virtual) and
p413 (Mesasuring gearbox, position tracking tolerance window) can only be set via the
expert list.
6.14.2.3 Prerequisites
● Absolute encoder
● Firmware release ≥ 2.4
● CU310 or CU320 with Order No. 6SL3040- ....- 0AA1 and Version C or higher