Specifications

13-328 | OWNER’S GUIDE
Filter
The Module has nine selectable low-pass lters from 10 Hz to 100 kHz. The lter characteristic can be set to
Butterworth 2nd order or Bessel 2nd order. An additional xed lter inside this module is a 3rd order Bessel
lter with a guaranteed -3 dB bandwidth of 300 kHz.
DAQP-STG Amplier balance
The amplifier balance allows eliminating automatically all internal amplifier offsets. It switches the differential amplifier inputs
IN+ and IN- to the internal isolated GND reference point. Then the output offset of the module is automatically adjusted to zero
for all ranges. This function takes up to 8 seconds. Automatically previous stored sensor offset values are cleared.
Sensor Balance
Typically every strain gage sensor has a certain offset. That comes from manufacturing tolerances or because of sensor mount-
ing. By performing a bridge balance this sensor offset could be completely removed on the analog side up to 200 % of the actual
range. This allows using the full dynamic of the AD-board instead of losing resolution because of digital offset shifting. Output
offset and sensor balance may not exceed 200 % of range (20 % for ranges above 1 V).
Internal Completion Resistors
The DAQP-STG has an internal half bridge completion and two internal quarter bridge completions for 120 Ω and 350 Ω strain
gages. The used high precision resistors with low temperature drift allow a long- time stable measurement of almost every strain
gage type without using an external completion network.
Internal Shunt
With two internal shunt resistors (59.88 kΩ and 175 kΩ) and one spare socket for a customised shunt, the DAQP-STG has wide
flexibility in case of shunt calibration. A jumper network gives the possibility to connect the internal shunts to either Sense+
Sense – IN+ or IN- to be compatible to existing sensor types and correction calculation methods. This technology is used to cor-
rect the complete measurement chain gain error from the sensor input to the digital signal output. It is based on the known ratio
between the shunt resistor and the strain gage resistance.
Short
It switches the differential amplifier inputs IN+ and IN- from the input terminals to the internal isolated GND reference point.
With this function the absolute sensor offset could be determined.
CAL
It applies a high precision internal reference signal with 80% of the full scale value to the module. For ranges above 1V the
reference signal level is 20 % of range.
Self Test
The self test function is a software controlled procedure that checks in the first step the amplifier itself. In the second step a
basic sensor check will be performed. This test is only available in DeweSoft if an AD-Card is installed.
Part 1: Amplier Test
The amplifier offset is checked by using the Short function The 80% Cal signal is applied to the amplifier. The complete isolation
amplifier including the AD-Card is checked by using this test signal. The self test circuit switches the amplifier input to the posi-
tive excitation voltage, so also the input amplifier is checked. Warning: if there is a short circuit on the excitation this test will
fail.