Owner's manual

Block Diagram
xPosition
of actuator
y
1
Output
pressure
y
2
to actuator
Input (w) each
acc.to version:
•
Analog operation
4...20mA
(+FSK)
• Digital operation
FSK
13...36 VDC
•
Bus input
s Air supply 1.4 ... 6 bar (20... 90 psig)
Figure 7: Block diagram
7 Voltage Converter 11 Digital Controller 15 Position Sensor 19 Pressure Sensor
8 Interface Component 12 IP Module 16 Optional Gauges 20 Pressure Sensor
9 A/D Transformer 13 Pre-Amplifier 17 Local Keys 21 Outputs
10 Switch 14 Pneumatic Power Amplifier 18 LCDs 22 Optional Mechanical Limit Switch
Operation
With the universal positioner with input signal 4…20 mA or superimposed HART signal, the supply takes place via the power
signal adjacent to the input.
By means of voltage converter 7, derivation of the internal supply of the electronic takes place. The power value is measured,
in A/D transformer 9 converted, and directed via switch 10 to digital controller 11.
With PROFIBUS-PA or FOUNDATION Fieldbus, the SRD is powered by means of the bus lead. The positioner is operated
from a control system by sending a setpoint (setpoint value) to the positioner. The digital signal is directed via the interface
component 8 to the digital controller 11. By means of the voltage converter 7 the internal supply of the electronic is
established, fed via the bus lead.
With FoxCom digital operation, a DC voltage is provided at input w. On this voltage a FSK-signal is modulated. The modulation
contains information (such as setpoint value), sent digitally to the control unit 11 across the FSK-unit 8.
The output of controller 11 drives the electro-pneumatic converter (IP-module) 12, controlling a pre-amplifier 13, the
single acting (or double acting) pneumatic power amplifier 14. The output of the amplifier 14 is the output pressure y to
the actuator.
The pneumatic amplifiers are supplied with supply air s 1.4…6 bar (20…90 psig).
The position x of the actuator is sent to the control unit 11 by the position sensor (conductive plastic potentiometer) 15.
Optional gauges 16, pressure sensors 19, 20, inputs / outputs 21 (two binary outputs; a 4…20 mA output and alarm;
control inputs for ‘Open/Close’ and ‘Hold last value’) enable additional diagnostic indications and possible intervention. The
mechanical limit switch 22 (optional) enables independent alarm signals.
Adjusting, startup of the positioner, and the demand for internal information can be made using the local keys 17 with
indication given by LCDs 18 or LEDs.
Page 13
Method of Operation
August 2014 POS-UM-00009-EN-02