Burkert Type 8635 - Manual (Page 33)

8635 - 31
S
YSTEM
D
ESCRIPTION
(PROFIBUS PA)
The SIDE Control (PROFIBUS PA) controls the position of the pneumatic actuator, whereby the position
sensor measures the actual position (POS) of the actuator. The controller compares this actual value of
the position with the setpoint (CMD), which may be set via the PROFIBUS PA. If a control difference
(Xd1) exists, a pulse-width modulated voltage signal is sent to the positioning system as the correcting
variable. If the difference is positive, the pressurizing piezoelectric valve is driven via output B1; if it is
negative, the exhausting piezoelectric valve is driven via output E1. In this way, the position of the
actuator is altered until the control difference is 0. Z1 represents a disturbance.
Operation as a positioner (PROFIBUS PA)
Position sensor
Position
setpoint Positioner Positioning system
(piezoelectric valves) Continuous
valve
Valve opening
Position control loop