Description
| Product model | PXI-4351 |
| Manufacturer | National Instruments (NI) |
| Product category | PXI Analog Input Module |
| Number of channels | 64 single-ended or 32 differential |
| Sensor types supported | Thermocouples (J, K, T, E, R, S, B, N), RTDs (2-/3-/4-wire), Strain gauges, Voltage (±10 V max) |
| ADC resolution | 24-bit sigma-delta |
| Sampling rate | Up to 1.25 kS/s per channel (shared ADC) |
| Simultaneous sampling | No (multiplexed) |
| Input ranges | ±10 V, ±5 V, ±2 V, ±1 V, ±0.5 V, ±0.2 V, ±0.1 V, ±0.05 V |
| Input impedance | >10 GΩ (for voltage measurements) |
| Signal conditioning | Built-in amplification, filtering, cold-junction compensation (CJC) |
| CJC accuracy | ±0.5°C |
| Bridge excitation | +2.5 V, +5 V, +10 V (programmable, isolated) |
| Filter type | Anti-aliasing filter, digital post-processing filter |
| Isolation | Channel-to-earth ground isolation up to 250 VAC |
| Connector type | Screw-terminal block (SCXI-1327 or equivalent) |
| Compatible chassis | PXI or PXI-Express chassis with PXI-1 (e.g., PXI-1031, PXI-1045) |
| Power consumption | < 5 W |
| Operating temperature | 0°C to 55°C |
| Storage temperature | -20°C to 70°C |
| Certifications | CE, FCC, UL, CSA, IEC 61010-1 |
| Warranty | 1 year (standard, when purchased new) |
Product introduction
The NI PXI-4351 is a high-density, 24-bit analog input module designed by National Instruments (NI) for precision measurement of low-level signals in industrial, research, and test environments. As part of NI’s SCXI (Signal Conditioning eXtensions for Instrumentation) architecture integrated into the PXI platform, the PXI-4351 provides 64 single-ended or 32 differential input channels optimized for thermocouples, RTDs (Resistance Temperature Detectors), strain gauges, and low-voltage signals.
This module is engineered for applications requiring high channel count and high accuracy, such as thermal profiling, structural testing, environmental monitoring, and material testing. It features a 24-bit sigma-delta ADC that delivers excellent resolution and noise rejection, enabling precise measurement of small voltage changes from sensors.
The PXI-4351 includes onboard signal conditioning such as programmable gain amplifiers, anti-aliasing filters, and cold-junction compensation (CJC) for thermocouples. The integrated CJC sensor ensures accurate temperature readings by compensating for the reference junction temperature in thermocouple circuits.
It connects to sensors via a screw-terminal block (typically SCXI-1327 or compatible), which provides secure, reliable connections for field wiring. The module supports isolated bridge excitation supplies (+2.5V, +5V, +10V), essential for powering strain gauges and RTDs without ground loops.
Data is acquired using a multiplexed architecture, meaning channels are sampled sequentially rather than simultaneously. While not truly simultaneous, the fast per-channel scan rate (up to 1.25 kS/s) and synchronized timing engine allow for tightly coordinated measurements across all channels.
NI PXI-4351
Core advantages and technical highlights
A major advantage of the PXI-4351 is its high channel density (64 SE) in a single 3U PXI slot, making it ideal for space-constrained systems or applications requiring hundreds of measurement points when used with multiple modules.
The 24-bit resolution and programmable input ranges (from ±10 V down to ±50 mV) enable the module to capture both large and very small signals with high dynamic range, minimizing the need for external amplification.
Its built-in cold-junction compensation and support for multiple thermocouple types (J, K, T, E, R, S, B, N) simplify temperature measurement setups, reducing wiring complexity and potential error sources.
The channel-to-earth ground isolation (250 VAC) enhances safety and noise immunity, especially in industrial environments with high electrical interference or ground potential differences.
The module is fully compatible with NI-DAQmx driver software, enabling seamless integration with LabVIEW, LabWindows/CVI, and .NET for rapid application development. It also supports SCXI signal conditioning modules when used in hybrid systems for additional filtering, isolation, or amplification.
Designed for long-term reliability, the PXI-4351 meets industrial safety standards (IEC 61010-1) and operates in harsh environments from 0°C to 55°C.
Typical application scenarios
The PXI-4351 is widely used in thermal testing of engines, batteries, and electronic components, where dozens of thermocouples are deployed to map temperature distribution.
In structural health monitoring and aerospace testing, it acquires data from strain gauges and bridge-based sensors on wings, fuselages, or bridges to measure stress, load, and deflection.
For environmental and climate chamber monitoring, the PXI-4351 logs temperature and humidity data from multiple RTDs and sensors over extended periods.
It is also used in automotive durability testing, power plant monitoring, and university research labs for multi-channel data logging.
Due to its SCXI heritage, it is often found in legacy test systems that were originally built with SCXI racks and later migrated to PXI for higher performance and smaller footprint.
Related model recommendations
- NI PXI-4350 Series: Similar modules with different channel counts or features.
- NI 921x Series (e.g., 9211, 9217, 9237): ModernC-Series modules for CompactDAQ/CompactRIO with thermocouple, RTD, and strain support.
- NI PXIe-4300 Series: PXI Express equivalents with higher performance.
- NI SCXI-1581/112x: SCXI signal conditioning modules for use with DAQ boards.
- NI PXI-628x Series: High-speed MIO DAQ modules for voltage-only measurements.
- Keysight 34972A with 34901A: Data acquisition/switch unit with thermocouple support.
- Yokogawa DL850E + 720201: ScopeCorder with high-channel-count sensor input.
- HBM QuantumX: Modular data acquisition system for strain, torque, and temperature.
- Siemens Simatic S7-1200/1500 with analog modules: PLC-based measurement solution.
- Advantech ADAM-4000/6000: Industrial I/O modules for distributed sensing.
NI PXI-4351
Installation, commissioning and maintenance instructions
Install the PXI-4351 in a PXI chassis (e.g., PXI-1031) and secure it with screws. Connect the SCXI-1327 screw-terminal block or compatible connector block to the module’s front connector.
Wire thermocouples, RTDs, or strain gauges to the terminal block, observing proper polarity and excitation connections. For RTDs and strain gauges, use 2-, 3-, or 4-wire configurations as needed to minimize lead resistance errors.
Use NI MAX (Measurement & Automation Explorer) to detect the module, configure channel types (e.g., thermocouple type K), input ranges, and sampling rates. Perform a self-calibration if required.
In LabVIEW, use DAQ Assistant or DAQmx VIs to create a multi-channel acquisition task. Enable CJC and excitation settings in software.
Ensure proper grounding and shielding to minimize noise. Avoid running sensor wires parallel to power cables. Clean terminals periodically and inspect for corrosion.
