Specifications

E-500/E-501 Series PZT Servo Controllers User Manual PZ 62E
Release 2.15.1 www.pi.ws Page 17
4.6. Starting Operation
4.6.1. Analog Operation
INFORMATION
The external analog signal can be generated by a computer (e.g. from a data acquisition
board). You can use the PI LabVIEW analog driver to generate the analog signal.
 See the E500T0011 Technical Note for how to download the driver set from our website.
1. Turn all DC-OFFSET potentiometers CCW (zero offset).
2. Turn all SERVO switches to OFF (open-loop operation).
Position servo-controllers can be operated in closed-loop (SERVO=ON, control input
is interpreted as target position) and open-loop (SERVO=OFF, control input
determines the output voltage directly) modes.
In closed-loop mode, the servo-control circuit is active and compares the sensor
signal with the target position. Hysteresis effects, nonlinearities and drift effects
are eliminated.
In open-loop mode, the servo-control circuit is deactivated. The device works as a
high-voltage amplifier. The input signal is amplified by the gain factor, and output
to the piezo actuator. The output signal can also be offset manually with the DC-
OFFSET potentiometer. In open-loop, the position sensor, if installed, is still active
and the real-time position reading is correct.
3. Turn the power on.
The standard screen appears on the display. The current output voltages and
displacements derived from the sensor signals are displayed for all channels.
Because the controller is set to open-loop mode, the sensor reading is not fed
back to control the position. If external forces act on the piezo actuator, its length
will change accordingly and so will the sensor reading.
4. Switch the Servo switches to ON (closed-loop).
Now the displacement is controlled in closed-loop servo-mode. The display shows
the current displacement values, as before.
5. Use the DC-Offset potentiometer to change the expansion.
6. Apply an external analog signal from 0 to +10 volts to control the expansion over the
nominal range.
The expansion of the piezo actuator can be controlled either by the DC-OFFSET
potentiometer or by an analog control input voltage applied to the CONTROL
INPUT socket. In the latter case, the potentiometer setting is used as an offset to
the control input voltage. This allows generation of unipolar output voltages from
bipolar control voltages.
7. Watch the yellow overflow LED on the servo-module. If it lights up, the amplifier output is
being clipped at one of its limits and the current displacement of the piezo actuator no
longer complies with the control signal. Use the ZERO trim potentiometer to adjust the
sensor reading window. Trim the potentiometer until the overflow LED stays dark.
4.6.2. Computer Controlled Operation
If an E-517 Interface/display unit is installed, remote control via TCP/IP, USB, RS-232 or
IEEE-488 interface is possible. A comprehensive command set allows controlling any
motion of the piezo actuator with maximum resolution (depending on the sensor installed).
See User Manual for the interface unit for details.
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