A new and powerful addition to Crystal Instruments EDM software is enhanced support for load cells and other ratiometric sensors. The sensitivities of these sensors are dependent on the supplied excitation voltage, so it is crucial to provide precise excitation. Crystal Instruments’ latest software release of EDM 9.0 provides an effortless process to configure and setup load cells and other ratiometric sensors.
When EDM detects a Spider-80SG or Spider-80SGi module, it automatically enables an option to set bridge-based sensor as one of the input modes. It also allows different input types on the same module, e.g., the user can have a load cell in Ch 1, a DC- Differential Strain gauge in Ch 2 and an AC differential MEMS accelerometer in Ch 3.
The sensitivity is defined in terms of mV / V / units and this sensitivity is scaled with respect to the excitation voltage. The user has three options to set the excitation voltage:
Auto: The Auto option defaults to the system specified excitation voltage
Remote Sensing: The precise excitation is measured using across the sensor terminals and that value is used for the measurements.
Manually enter: This option is used if the user is supplying external excitation to the sensor
The screenshot displays the auto value as +/- 2.5 V. However, the remote sensing option accurately measures voltage across the terminals of the system since voltage drops result from lead wire resistances or other such factors. Based on this, it is recommended to use the remote sensing option.
The offset nulling menu displays the Sensitivity scaled by the voltage. The second picture shows the value when we use the default auto value. This can lead to a significant difference if longer lead wires or wider measurement ranges are used or if narrow tolerances are needed.
With just a few simple clicks users can set up any ratiometric sensor and start measuring values. Click on run and the test checklist displays a summary of all the test settings including the channel settings. The user can also enter a run description or notes for that specific run before starting the measurements.
Ratiometric measurements can also be used in parallel with Crystal Instruments vibration controller to provide advanced drive limiting and notching functions which are widely used in aerospace testing. Ratiometric sensors are among the many essential tools provided by Crystal Instruments’ Spider systems and EDM Software for engineering professionals.