Universal Signal Conditioner with Electrical Isolation

NASA’s Kennedy Space Center owns approximately 700 Dewetron DAQP-STG modules, which they use to measure vital spacecraft parameters. With its built-in high-precision DC and constant current sensor supply the DAQP-STG enables direct connection of quarter, half and full bridges, piezoresistive bridges, resistors, potentiometers and Pt100 to Pt1000 sensors. It can also directly measure voltages to ±10V. Higher voltages to ±200V, thermocouples and IEPE (ICP) or charge sensors are supported using MSI, Modular Smart Interfaces.

The module is primarily designed as a high-end bridge amplifier, and accordingly meets all requirements for strain gauge/bridge sensors. There are 13 predefined measurement ranges from ±0.1 mV/V to ±1000 mV/V, but any sensitivity can be programmed. So for example you could enter unusual numbers like “2.27 mV/V.” This flexibility allows the engineer to make full use of the dynamic capabilities of the measuring system.

Internal precision resistors supplement any half bridge resistance from 80Ω to 10 kΩ, as well as quarter bridges of 120Ω or 350Ω. In addition, there are two more internal resistors for shunt calibration. Automatic balancing of sensor offsets up to 200% of the measurement range is available with the click of one button within the software setup screen.

The user may select 0-12 VDC (constant voltage) or 0 -20 mA (constant current) as the sensor supply, both are precisely created by on-board 16-bit digital-to-analog converters, and both are fully adjustable.

The module offers nine userselectable low-pass filters in the bandwidth to 300 kHz. It is extremely low-noise, and combines the highest precision with very small dimensions.

Its flexibility makes the DAQP-STG module suitable for very exacting measurements, such as resistance from 25 mΩ to 100 kΩ, or for very fast thermocouple measurements with electrical isolation. To do this, a thermocouple can be connected to the DAQP-STG module with an MSI (Modular Smart Interface). There are certain ballistics tests which require very high bandwidth thermocouple measurements, and the DAQP-STG provides them up to 300 kHz with real galvanic isolation to prevent electrical noise from overwhelming the small mV signals.

As with all DEWETRON DAQP series modules, the output of the DAQPSTG is an analog ±5 V signal, suitable for any measurement system.

TEDS, a standardized interface for automatic sensor detection and parameter transfer, is fully supported by the DAQP-STG signal conditioner, and DEWESoft software.

The universal input allows connection of a very wide range of sensors. The electrical isolation and high overvoltage protection make this amplifier almost indestructible, and thus a safe investment for many years of use.