Burster 9243 - Input Reference Point; Cutoff Frequency; Calibration Source

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6.4 Input reference point
The signal amplifier acts as a differential amplifier. This means that the negative signal output is
not connected to ground. If a ground connection is required, it must be established externally.
6.5 Cutoff frequency
Using DIP switches, the cutoff frequency can be switched between 10 Hz and 1 Hz (-3dB). The
switch settings are described in Chapter 4.1.3 titled Meaning of the DIP switches Page 13.
6.6 Calibration source
The 9243 amplifier module is equipped with a 5.000 mV precision voltage source for the
purpose of calibration. This voltage source is referenced to ground and must be connected
externally when calibration is required.
Observe the following procedure for this:
1. Disconnect the sensor.
2. Connect pin 9 with pin 13 and pin 14.
3. Ajust “0 V” at the voltage output.
4. Connect pin 14 with pin 8.
5. Adjust the calculated voltage output.
Example:
Given: Strain gauge sensor 350 ohms
Rated characteristic value 1.5 mV/V
Sensor excitation voltage 5 V
Required output voltage U
O
from the amplifier 10 V
Wanted: The amplifier output voltage U
OCAL
to be set for a calibration excitation
voltage U
ICAL
= 5.000 mV
1
st
step: Calculate and set the gain for 1.5 mV/V as described in the example in
Chapter 6.
When rough changes should be a repetition starting from step 2.
2
nd
step: Calculate the amplifier output UOCAL (to be fine-adjusted) when
U
ICAL
= 5.000 mV is applied instead of the input voltage U
I
supplied by
the sensor (7.5 mV in this example):


=


× 



=
10  × 5 
7.5 
= 6.666 
U
I
= Output of the sensor x excitation voltage
U
O
= Output of the amplifier with U
I
U
ICAL
= 5.000 mV calibration voltage
U
OCAL
= Output of the amplifier with U
ICAL
In this example, a voltage of 6.666V needs to be set at the amplifier output.