Burkert 8694 - Type 8694 Positioner (Position Controller); Schematic Representation of the Position Control Type 8694

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System description
5.5 Type 8694 positioner (position controller)
The position sensor records the current position (POS) of the pneumatic actuator. The position controller com-
paresthisactualpositionvaluewiththeset-pointvalue(CMD)whichisdenableasstandardsignal.Incaseofa
control deviation (Xd1), a pulse-width modulated voltage signal is sent to the pilot valve system as a manipulated
variable.Ifthereisapositivecontroldierenceinsingle-actingactuators,theairinletvalveiscontrolledvia
outputB1.Ifthecontroldierenceisnegative,thebleedvalveiscontrolledviaoutputE1.Inthiswaythe
positionoftheactuatorischangeduntilcontroldierenceis0.Z1representsadisturbancevariable.
Valve opening
Valve
Pilot valve
system
Position sensor
Position
controller
Position
set-point
value
CMD Xd1
B1
E1
P
K
Z1
POS
Position control
circuit
+
-
Figure 4: Signal ow plan of position controller
5.5.1 Schematic representation of the position control Type 8694
büS, IO-Link
4 – 20 mA
1)
0 – 20 mA
CHARACT
SPLTRNG
2)
DIR.CMD
CUTOFF
X.TIME
2)
X.CONTROL
DBND
POS
CMD*
CMD
DIR.ACT
2)
X.LIMIT
2)
1) Factory setting
2) Can only be activated with communications software
Figure 5: Schematic representation of position control
english
Type 8694 REV.2