NI PXIe-4340

Core Technical & Performance Specifications

1. Channel Configuration: Eight fully differential, galvanically isolated analog input channels on single-width 3U PXI Express module
2. Full-Scale Analog Input Voltage Range: ±600 V DC / AC RMS per differential channel
3. Analog-to-Digital Converter Architecture: 24-bit delta-sigma ADC per independent channel
4. Maximum Simultaneous Sampling Rate: 51.2 kS/s aggregate sampling rate across all eight channels
5. Programmable Analog Low-Pass Filter Cutoff Frequencies: 0.4 Hz, 4 Hz, 40 Hz, 400 Hz software configurable per channel
6. Galvanic Isolation Rating: 1,500 V RMS channel-to-backplane isolation, 1,000 V RMS channel-to-channel isolation
7. Common-Mode Voltage Rejection Ratio (CMRR): 120 dB minimum at 50 Hz / 60 Hz industrial mains noise frequencies
8. Onboard Data Storage: Multi-channel FIFO streaming buffer for continuous unattended long-duration data logging
9. Physical & Environmental Specifications
   • Form Factor: Single-width 3U PXI Express module
   • Operating Ambient Temperature Range: 0 °C to 55 °C
   • Storage Temperature Range: -40 °C to 85 °C
   • Relative Humidity Operating Rating: 10%–90% non-condensing
   • Maximum Operating Altitude: 2000 m above sea level

Key Functional Features

1. Eight independent fully differential galvanically isolated high-voltage analog input channels integrated within compact single-slot PXI Express hardware, supporting multi-point industrial high-voltage signal monitoring with minimal chassis slot occupation
2. Reinforced galvanic isolation architecture separating field-side ±600 V industrial high-voltage sensor signals and low-voltage PXI Express digital backplane bus circuits, fully blocking ground loop noise, industrial surge transients and high-voltage fault current from damaging host control hardware
3. High-resolution 24-bit delta-sigma ADC per channel delivers ultra-fine voltage measurement resolution for precise detection of small-magnitude voltage fluctuations superimposed on large industrial high-voltage DC or AC bias signals
4. Software-programmable multi-stage analog low-pass noise filtering per channel, optimized to suppress 50 Hz / 60 Hz industrial mains power line noise, motor switching EMI noise and mechanical vibration induced signal interference
5. Simultaneous multi-channel synchronized sampling architecture fully compatible with PXI Express chassis backplane 10 MHz reference clock and star trigger bus, enabling precise time-aligned multi-channel high-voltage waveform capture for power grid transient disturbance recording and motor drive fault diagnosis
6. Hardware-triggered continuous streaming data logging capability with large onboard multi-channel FIFO buffer, supporting unattended long-duration industrial monitoring test workflows without host PC data loss or sampling rate throttling
7. Complete NI DAQmx instrument driver software support with full compatibility for LabVIEW, LabWindows/CVI, Python, C#, C++ and TestStand automated industrial test sequencing software environments
8. Integrated multi-layer surge and transient overvoltage protection circuits on every analog input channel, clamping hazardous industrial voltage surge spikes to safe operating levels and preventing permanent ADC and isolation component damage during unforeseen field-side high-voltage fault events

Working Principle

1. Galvanically Isolated Analog Input Signal Path

   External industrial high-voltage differential sensor signals (0 to ±600 V DC/AC) connect to front-panel differential input terminal pairs. Each channel incorporates reinforced optocoupler isolation barrier circuits separating field-side high-voltage signal conditioning circuits and low-voltage digital control circuits connected to the PXI Express backplane bus. Isolation barriers fully block DC ground loop current flow and suppress high-frequency industrial EMI noise coupling between field wiring and host measurement hardware.

2. Programmable Analog Low-Pass Noise Filtering Operation

   Isolated differential analog input signals pass through software-configurable RC low-pass filter networks with selectable cutoff frequency settings. Low-pass filtering attenuates high-frequency industrial mains harmonics, motor switching noise and mechanical vibration induced signal fluctuations before conditioned analog voltage signals enter the 24-bit delta-sigma ADC conversion stage.

3. 24-Bit Delta-Sigma ADC Sampling & Digital Conversion

   Each channel’s conditioned filtered analog voltage signal feeds into dedicated independent 24-bit delta-sigma analog-to-digital converter hardware. Delta-sigma ADC architecture oversamples analog input signals at high internal clock frequencies and utilizes digital decimation filtering to produce high-resolution low-noise digital voltage measurement data. All eight channel ADC sampling events can be synchronized to the global chassis 10 MHz reference clock timing signal for time-aligned multi-channel waveform acquisition.

4. Onboard FPGA Digital Control & Streaming Data Buffering

   Industrial-grade onboard FPGA digital logic hardware independently manages multi-channel ADC sampling sequencing, programmable digital decimation filtering, hardware trigger signal detection and multi-channel FIFO measurement data buffer storage operations without relying on host PC CPU processing cycles. Digital voltage measurement data streams continuously from per-channel ADC circuits into shared multi-channel onboard FIFO buffer memory. The FIFO buffer eliminates host PC communication bandwidth bottlenecks, enabling uninterrupted long-duration unattended industrial data logging operations.

5. Multi-Stage Input Surge Overvoltage Fault Protection Mechanism

   Each differential analog input channel integrates series current-limiting resistors, bidirectional transient voltage suppression diodes and gas discharge tube surge suppression components arranged in multi-stage protection topology. When hazardous high-voltage surge transients or fault voltage spikes enter channel input terminals, the multi-stage protection circuit instantly clamps excess voltage magnitudes to safe operating levels and diverts surge fault current away from sensitive ADC and isolation barrier components to prevent permanent module hardware damage.