Siemens SIPART PS2 Operating Instructions Manual page 260

External position detection with NCS or external position detection system
B.2 Non-Contacting Sensor
①
②
Figure B-1
The figure shows that a circular movement of the magnet generates a sinusoidal change of
the resistance. The mechanical stops of the fitting ensure that only one part (quadrant) of the
sinusoidal curve is used at any one time. The principle-related non-linearity of the curve is
corrected by means of software based on a curve that is stored in the positioner.
A linear movement of the magnet in the sensor range also generates a resistance change that
is used to identify the position. The following figure highlights the principle:
①
②
Figure B-2
Non-linearity is corrected automatically in the SIPART PS2 positioner by software.
The great advantage of this principle is the absence of wear. Moreover, vibration, dampness
and temperature only have a minor impact on the measurement result.
260
Magnet
Sensor
Relative resistance change depending on the angle of the magnet
Magnet
Sensor
Resistance change depending on the position of the magnet
③
Resistance change
④
Angle
③
Resistance change
④
Angle
SIPART PS2 with and without HART
Operating Instructions, 05/2017, A5E00074631-AC