The NI 9239 is a 4-channel C Series voltage input module designed for high-accuracy differential analog measurements in industrial and laboratory data acquisition systems. It delivers 24-bit resolution with simultaneous sampling across all channels, capturing detailed voltage readings at up to 50 kS/s per channel. Channel-to-channel isolation rated at 250 V RMS (CAT II) protects equipment from voltage transients and eliminates ground-loop errors. The module integrates directly into NI CompactDAQ and CompactRIO platforms via screw terminal connectivity, offering floating input channels independent of earth ground.
Technical Specifications
Input Configuration
• 4 differential analog input channels with simultaneous sampling
• 24-bit resolution
• DC input coupling
• ±10 V nominal measurement range (typical ±10.52 V, minimum ±10.3 V)
• High input impedance when idle
Sampling & Timing
• Maximum sampling rate: 50 kS/s per channel
• Internal master timebase: 12.8 MHz
• External master timebase supported with cross-module synchronization
Filtering
• Analog and digital filtering combination
• Passband flatness: ±100 mdB maximum at 50 kS/s
• Stopband frequency: 0.547 × fs with 100 dB rejection
• Alias-free bandwidth: Data rate minus stopband frequency
Accuracy (Calibrated at 25 °C ±5 °C)
• Gain error: ±0.03% typical, ±0.13% maximum
• Offset error: ±0.008% typical, ±0.05% maximum
Accuracy (Uncalibrated at 25 °C ±5 °C)
• Gain error: ±0.3% typical, ±1.2% maximum
• Offset error: ±0.11% typical, ±0.55% maximum
Power & Environment
• Active mode consumption: 740 mW maximum
• Sleep mode consumption: 25 μW maximum
• Operating temperature: -40 °C to 70 °C
• Storage temperature: -40 °C to 85 °C
– Key Features
• Floating input channels isolated from earth ground and each other
• Channel-to-channel isolation: 250 V RMS, CAT II (screw terminal)
• Simultaneous multi-channel sampling eliminates skew between channels
• Combination analog/digital filtering minimizes aliasing artifacts
– Typical Applications
• Power supply monitoring and validation
• Sensor signal conditioning and measurement
• Environmental monitoring systems
• Industrial process control instrumentation
• Laboratory test automation
– Compatibility & Integration
The module mounts directly into NI CompactDAQ and CompactRIO systems. Screw terminal connectivity simplifies field wiring without requiring external signal conditioning.
