National Instruments NI 9242 Analog Input Module

The National Instruments NI 9242 is a C Series analog input module designed for high-precision voltage measurements in CompactRIO and CompactDAQ systems. It features 4 differential analog input channels with a ±10 V input range, 24-bit resolution, and simultaneous sampling at rates up to 50 kS/s per channel. The module includes an integrated programmable gain amplifier (PGA) and a built-in anti-aliasing filter. It is ideal for applications requiring accurate measurement of sensors such as strain gauges, accelerometers, and pressure transducers. The NI 9242 is hot-swappable and operates over a wide temperature range.

Technical Specifications

Number of channels: 4 differential. Input voltage range: ±10 V. Resolution: 24 bits. Maximum sampling rate: 50 kS/s per channel (simultaneous). Input impedance: 1 GΩ (parallel with 47 pF). Accuracy: ±0.05% of reading ±1.5 mV offset (at 25°C). Offset drift: ±15 µV/°C. Gain drift: ±10 ppm/°C. Input noise: 50 µVrms typical at 50 kS/s. Overvoltage protection: ±30 V. Coupling: DC only. Power consumption: 650 mW (typical). Operating temperature: -40°C to +70°C. Storage: -40°C to +85°C. Dimensions: 30 mm × 90 mm × 23 mm (C Series form factor). Weight: 150 g. Connector: 10-pin spring terminal or screw terminal. Certifications: CE, FCC, RoHS.

Key Features

• 4 simultaneous-sampling analog inputs, ±10 V range

• 24-bit ADC with programmable gain

• Up to 50 kS/s per channel throughput

• High impedance input (1 GΩ) for minimal loading

• Built-in anti-aliasing and noise rejection filters

• Hot-swappable in CompactRIO/CompactDAQ chassis

• Wide operating temperature range (-40°C to +70°C)

• Compatible with LabVIEW, FlexLogger, and DAQExpress

Measurement Performance

The NI 9242’s 24-bit resolution and simultaneous sampling make it suitable for dynamic measurements where phase information between channels is critical. The built-in PGA allows the user to match the input range to the sensor output (gain settings: 1, 2, 5, 10, 20). The module’s low noise and drift ensure stable readings over time and temperature. For applications requiring isolation, consider the NI 9242’s non-isolated design; for isolated inputs, other C Series modules are available.

Software Integration

The NI 9242 is fully supported by NI-DAQmx driver software, which provides access to advanced timing, triggering, and scaling functions. In LabVIEW Real-Time or LabVIEW FPGA (when used with CompactRIO), users can implement custom processing, such as filtering and peak detection. The module also supports hardware-timed single-point (HWTSP) mode for fast control loops.

Applications

Typical applications include battery voltage monitoring, strain gauge measurements (with external bridge completion), accelerometer signal conditioning, power quality analysis, and general laboratory data acquisition. It is also used in industrial condition monitoring and predictive maintenance systems.

Installation and Wiring

Insert the NI 9242 into any C Series slot of a CompactRIO (e.g., cRIO-904x) or CompactDAQ (e.g., cDAQ-917x) chassis. Use the supplied connector (spring or screw) for field wiring. Connect the signal (+) and signal (-) to the appropriate pins. For grounded sensors, use differential wiring. For floating sensors, add bias resistors as recommended in the manual. The module is automatically detected by NI software.

Maintenance and Calibration

The NI 9242 is factory calibrated. For best accuracy, perform an external calibration every 1-2 years using a precision voltage source. The module has no user-serviceable parts. Keep the connector pins clean and store in an anti-static bag when not in use.

Conclusion

The National Instruments NI 9242 provides high-resolution, simultaneous analog input for precision measurement applications. Its 24-bit ADC, high input impedance, and wide temperature range make it a versatile choice for CompactRIO and CompactDAQ systems.