Model Explanation

• PXI‑4351: Base model number (PXI bus, 4351 series).

• 777790‑01: NI catalog order number.

• 185450D‑01: Hardware revision identifier.

• Function: Precision Thermocouple/RTD/Voltage Input Module.

• Compatibility: PXI/PXIe chassis (5 V peripheral slot); works with LabVIEW, LabWindows/CVI, NI‑DAQmx.

Technical Parameters

• ADC Resolution: 24‑bit Δ‑Σ

• Channels: 14 × thermocouple / 16 × differential voltage

• Input Ranges: ±3 V, ±10 V (software‑selectable)

• Max Sampling Rate: 100 kHz (aggregate); 1 kS/s per channel typical

• Temperature Sensors:

  • Thermocouple: J, K, T, E, N, R, S, B (‑200 °C to +1820 °C)

  • RTD: PT100, PT1000 (‑200 °C to +600 °C)

  • Thermistor: NTC/PTC via 1 mA excitation

• Excitation: Built‑in 1 mA precision current source (for RTD/thermistor, up to 15 kΩ)

• Isolation: Channel‑to‑earth 250 VAC; 2500 Vrms optical isolation

• CMRR: >120 dB (50/60 Hz)

• Input Impedance: 1 MΩ || 20 pF

• Digital I/O: 8 × TTL‑compatible (programmable)

• Operating Temp: 0 °C to +55 °C

• Dimensions: 3U PXI (100 × 160 × 30 mm); 250 g

Interface & Communication Configuration

• Bus: PXI backplane (32‑bit, 33 MHz)

• Connectors:

  • Front: 68‑pin SCSI‑II for analog/digital I/O

  • Rear: PXI edge connector (power, clock, trigger)

• Synchronization: PXI trigger bus; external trigger in/out

• Calibration: Fully software‑calibrated (no trim pots)

• Drivers: NI‑DAQmx, VISA, IVI‑COM; Windows/Linux support

Core Functions

1. Multi‑Sensor Temperature Measurement: Direct support for thermocouples, RTDs, and thermistors with cold‑junction compensation (CJC).

2. Precision Voltage Acquisition: 24‑bit resolution for low‑level signals; software‑selectable ranges and filtering.

3. Resistance Measurement: 1 mA current source for RTD/thermistor/ohms (up to 15 kΩ).

4. Open‑Circuit Detection: Software‑programmable thermocouple break detection.

5. Isolation & Noise Rejection: Analog/digital filtering + galvanic isolation for industrial noise immunity.

Application Scenarios

• Aerospace: Environmental chamber monitoring, engine thermal profiling.

• Automotive: Battery pack temperature, ECU thermal testing, dynamometer cells.

• Industrial Automation: Furnace/oven monitoring, extrusion line temperature control.

• Semiconductor: Wafer probing, thermal vacuum chamber data logging.

• Research & Lab: Precision calorimetry, material thermal characterization.

Operation & Maintenance Instructions

Installation

• Insert into 5 V PXI peripheral slot; secure with front panel screws.

• Connect sensors to 68‑pin front connector (follow pinout diagram).

• Install NI‑DAQmx; configure in MAX (Measurement & Automation Explorer).

Maintenance

• Quarterly: Inspect 68‑pin connector for dirt/wear; tighten if needed.

• Semi‑annually: Power off, clean with ESD‑safe dry cloth; verify calibration via MAX.

• Replacement: Use only NI PXI‑4351; auto‑detected by DAQmx (no jumpers).

Troubleshooting

• No Temperature Reading: Check CJC setup, thermocouple polarity, and wiring for opens.

• Noisy Readings: Enable digital filtering; check grounding and isolation; avoid long unshielded cables.

• Module Not Detected: Verify PXI slot power; reseat module; update DAQmx drivers.

Precautions

• Isolation Safety: Do not exceed 250 VAC channel‑to‑earth; isolate high‑voltage circuits.

• ESD Protection: Use wrist strap when handling module; store in anti‑static bag.

• Sensor Wiring: Use shielded twisted‑pair cables; separate analog/digital wiring to reduce noise。