User Manual
E727T0005, valid for E-727
BRO, 2019-06-28
Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany
Page 63 / 240
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email
INFORMATION
AutoZero is to be performed with linear axes only. Starting AutoZero for rotation axes will fail and
cause the error code 74 („No sensor channel or no piezo channel connected to selected axis
(sensor and piezo matrix)“).
Objective and Prerequisites of AutoZero
The AutoZero procedure performs automatic zero point adjustment of the sensors.
Objective of AutoZero:
Make the entire travel range available:
Changes in temperature or changes in the mechanical load can cause small
deviations of the sensor zero point. When the sensor zero-point is set correctly, the
complete output voltage range of the amplifier can be used in closed-loop
operation.
Prevent the piezo actuators from damage:
In open-loop operation, the stage displacement with 0 V piezo voltage should
already be about 10 % of the travel range. Then the average applied voltage is
reduced which lengthens the lifetime of the piezo actuator in the stage without
reducing the nominal travel range.
Prerequisites for AutoZero:
LowVoltage < HighVoltage
(LowVoltage is given by the value of the
AutoZero Low Voltage
parameter (ID
0x07000a00);
HighVoltage is given by the value of the
AutoZero High Voltage
parameter (ID
0x07000a01))
The value of the
AutoZero High Voltage
parameter (ID 0x07000a01) should be
identical with the piezo voltage that is required for maximum displacement of the
axis.
Settings Changed by AutoZero
The AutoZero procedure changes the values of the parameters
Sensor Mech. Correction 1
(ID
0x02000200). With the E-727 models for piezoresistive sensors and for strain gauge sensors
(details see “Model Overview”, p. 13), the AutoZero procedure also changes
Sensor Offset factor
(ID 0x02000102).
Starting AutoZero via Command Entry
Via command entry, you have the following options to start the AutoZero procedure of the E-727:
Use the ATZ command to perform the AutoZero procedure once (see E-727
commands manual (PZ281E) for ATZ details). Afterwards save the values of the
parameters
Sensor Mech. Correction 1
(ID 0x02000200) and
Sensor Offset factor
(ID
0x02000102) to nonvolatile memory.
Send the ATZ command after every start or reboot of the E-727.
Set the value of the
Power Up AutoZero Enable
parameter (ID 0x07000802) to 1 for
all axes so that the AutoZero procedure is performed automatically with every start
or reboot of the E-727.