Product Overview
The National Instruments PXIe-4357 is an RTD input module for PXI Express systems. It provides 20 resistance temperature detector input channels with 24 bit resolution. The module is designed for temperature measurement in test, monitoring, and control applications where RTDs are preferred for stability and accuracy.
RTDs change resistance with temperature, so the module measures resistance and converts it to temperature using the configured sensor type. The PXIe-4357 includes built in excitation and signal conditioning to support this measurement. It is part of the NI PXI platform, which allows the module to be combined with switches, DMMs, and other instruments in one chassis.
RTD Measurement
The PXIe-4357 supports common RTD types such as two wire, three wire, and four wire configurations. Four wire measurement removes lead resistance errors and is preferred for high accuracy work. Three wire measurement offers a practical compromise for many industrial installations. Engineers should select the wiring configuration that matches the sensor and the required accuracy.
The module provides excitation current for the RTD and measures the resulting voltage to determine resistance. Built in filtering reduces noise and improves reading stability. Engineers should verify the RTD type, nominal resistance, and temperature coefficient in software so that the conversion to temperature is correct.
Resolution and Accuracy
Twenty four bit resolution supports fine temperature discrimination, which is useful in applications that must detect small thermal changes or monitor slow drift. The module is designed with low noise input circuitry to preserve measurement quality. Accuracy depends on the RTD type, wiring configuration, and the module specifications for the selected range.
Self heating is a consideration in RTD measurement because excitation current can warm the sensor. Engineers should confirm that the excitation level and sensor thermal path are appropriate for the measurement. In precision work, comparison calibration or a higher accuracy RTD may be needed to meet the required uncertainty.
Noise Rejection and Wiring
RTD signals are resistance based and can be affected by lead resistance and electrical noise. Shielded cable, consistent lead lengths, and separation from power wiring help maintain accuracy. For three wire and four wire configurations, lead resistance compensation depends on matched leads; mismatched leads can introduce errors.
Proper grounding and cable routing are important in industrial environments where motors, heaters, and drives are present. The module should be installed in a compatible PXI Express chassis with adequate ventilation. Engineers should also consider the temperature of the terminal area, since large temperature differences between the module and the sensor can affect readings.
Software and PXI Integration
The PXIe-4357 is supported by NI-DAQmx, which provides RTD type selection, wiring configuration, scaling, and calibration support. Applications can be developed in LabVIEW, LabWindows/CVI, Measurement Studio, and other NI-DAQmx compatible environments. The module can use TEDS with compatible sensors to simplify identification and setup.
Within a PXI Express chassis, the module can be synchronized with analog input, analog output, digital, and switching modules. This allows temperature data to be correlated with power, voltage, and control signals during a test sequence. Engineers can build automated profiles that change chamber setpoints, capture temperature response, and evaluate pass or fail criteria.
Typical Applications
Precision temperature monitoring with RTDs
Environmental chamber and thermal validation
Industrial process temperature measurement
Battery and power module thermal test
Calibration and metrology support
Multi point temperature monitoring in PXI systems
The PXIe-4357 provides 20 RTD input channels with 24 bit resolution and built in excitation in a PXI Express module. Its channel count and accuracy make it a practical instrument for multi point temperature measurement in automated test systems.
