7 Operation
E-625 Piezo Servo Controller
PZ166E
Version: 2.0.0
33
7.2.2
Servo Mode
The servo mode determines whether the motion is performed in open-loop operation (servo
mode OFF) or in closed-loop operation (servo mode ON).
The control and servo modes can be combined at will.
Closed-Loop Operation
Control input signals (input signal on
ANALOG IN/WTT
or E-816 inputs over commands and
wave table output) are interpreted as the target position.
The servo loop of the E-802 servo controller submodule determines the piezo voltage on the
basis of the target position and the feedback from the position sensor in the positioner. This is
how the servo loop regulates the position of the positioner.
The positioning in closed-loop operation is free of drift and hysteresis and independent of
changes in load.
Open-Loop Operation
Control input signals (input signal on
ANALOG IN/WTT
or E-816 inputs over commands and
wave table output) are interpreted as a direct specification for the piezo voltage.
In open-loop operation, the servo loop for the E-802 servo controller submodule is not
considered.
When the jumpers are set accordingly, the slew rate limiter and the notch filter remain active
(p. 38).
The sensor electronics work independently of the servo mode and report the current position
of the positioner when a sensor is connected, even in open-loop operation. Since even
positioners of the same model differ slightly, the voltage required to achieve nominal
displacement differs.
7.3
Selecting the Operating Mode
7.3.1
Selecting the Control Mode
The control mode is set with the
Settings
DIP switch block on the front panel of the E-625.
Analog Mode
The analog mode is active when the DIP switch setting is as follows:
DIP Switch
Setting
Switch Setting
1
ON
down
2
OFF
up
4
OFF
up
