National Instruments NI-9238 C Series Voltage Input Module

The National Instruments NI-9238 (Part Number: 783311-01) is a 24-Bit, 4-Channel Voltage Input Module from the C Series. The 4 analog channels are differential. This model can operate with differential analog inputs and has a measurement range of ±500 mV. The NI-9238 is compatible with a broad range of low-voltage sensors, such as current transducers and current shunts in high-current applications. When used in combination with a higher-voltage Input Module from the C Series, the NI 9238 can measure energy and power consumption for applications, such as industrial machine monitoring, appliance test, power quality analysis, harmonic analysis, and phasor measurements.

The National Instruments NI-9238 module offers 250 Vrms continuous, channel-to-channel isolation and can withstand up to 1,500 Vrms surge voltages. However, it is to be kept in mind that the isolation level changes dramatically with respect to altitude. The values mentioned above are valid for altitudes up to 2000 meters. The NI-9238 supports simultaneous sampling and can acquire samples at 50 kS/s per channel. This module comes equipped with an integrated, 12.8 MHz frequency master time base that regulates its data rate. Each of the four channels incorporated in this module has its own 24-bit resolution, analog-to-digital converter (ADC). Thus, each AI channel offers an independent signal path.

The National Instruments NI 9238 Voltage Input Module supports only DC input coupling and has screw-terminal connectivity. The input channels of this device operate at >1 GΩ impedance. While operating in typical conditions, the NI-9238 incurs 3.9 μ Vrms input noise. In optimum calibrated form, this device can operate with ±0.20% gain error and ±0.06% offset error. The device is equipped with a screw terminal front connector.

The NI-9238 is run using the NI-DAQmx driver software which is compatible with software packages such as LabVIEW, LabWindows/CVI, or Microsoft Visual C++. The NI device weighs 5.15 oz. It has a recommended operating temperature range of -40 °C to 70 °C, a storage temperature range of -40 °C to 85 °C, and a random and sinusoidal operating vibration of 5 grms and 5 g respectively – all at a frequency range of 10 to 500 Hz.