Description
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | National Instruments |
| Model | PXIe-4340 |
| Part number | 785068-01 |
| Product type | AC displacement input module |
| Form factor | 3U PXI Express peripheral module |
| Analog input channels | 4 |
| ADC resolution | 24-bit |
| Maximum sample rate | 25.6 kS/s per channel |
| Input range | ±7 Vrms |
| Supported sensors | AC LVDT, RVDT, resolver, synchro |
| Sensor wiring | 4-, 5-, and 6-wire LVDT/RVDT |
| Excitation voltage | 1–7 Vrms, in 0.5 Vrms increments |
| Excitation frequency | 400 Hz–10 kHz, in 10 Hz increments |
| Excitation output | Independent differential excitation per channel |
| Remote sensing | Differential remote-sense inputs |
| Trigger/synchronization | PFI 0, 3.3 V digital signal |
| Bus interface | PXI Express |
| Power requirements | 12 V at 0.9 A; 3.3 V at 0.9 A |
| Operating temperature | 0°C to 55°C |
| Dimensions | 16 × 10 cm (6.3 × 3.9 in.) |
| Weight | 168 g (5.9 oz.) |
| Recommended calibration interval | 1 year |
| Software | NI-DAQmx |
Specifications are based primarily on NI product and hardware documentation. Confirm the applicable revision and system configuration before using these values for test-system design.
Product Introduction
The National Instruments PXIe-4340 is a four-channel AC displacement measurement module designed for LVDT, RVDT, resolver, and synchro sensors. It combines 24-bit analog-to-digital conversion with configurable sensor excitation, allowing engineers to acquire displacement and angular-position signals through a PXI Express chassis.
Each channel supports independent excitation configuration and remote sensing. This makes the module useful in automated test systems where sensor excitation, signal acquisition, and repeatable measurement setup must be managed together.
PXIE-4340
Application Scenarios & Field Pitfalls (Engineer’s Perspective)
In a position-measurement test system, an unstable reading does not automatically indicate a defective sensor. Incorrect excitation frequency, unsuitable wiring, poor shielding, or an improperly configured remote-sense connection can all affect measurement results. The PXIe-4340 requires attention to both the sensor’s electrical characteristics and the DAQ configuration.
Typical application scenarios include:
- Servo and actuator testing: Measuring linear displacement through AC LVDT sensors during motion and positioning tests.
- Aerospace test equipment: Acquiring displacement and angular-position signals from supported LVDT, RVDT, resolver, and synchro sensors.
- Automotive validation: Monitoring actuator and mechanical-position feedback during automated test sequences.
- Industrial equipment development: Measuring mechanical travel and rotational position in automated machinery test stands.
Field pitfalls
1. Match excitation to the sensor. The module supports excitation from 1 to 7 Vrms and frequencies from 400 Hz to 10 kHz. These settings must match the sensor specifications. Incorrect excitation can produce inaccurate readings or prevent correct sensor operation.
2. Use the correct differential wiring. Each channel has separate analog input, excitation, and remote-sense connections. Check the sensor wiring diagram before connecting the AI, EX, and RS terminals. Use twisted, shielded pairs as specified by NI. Also, do not connect a grounded oscilloscope probe directly across the differential excitation output; this can short one side of the excitation circuit.
3. Verify the terminal block and software environment. The compatible front-mount terminal block is TB-4340, part number 784087-01. Confirm the PXI Express chassis slot, connector condition, NI-DAQmx driver support, and channel configuration before commissioning.
For incoming inspection, check the module’s 96-pin connector, front-panel condition, captive screws, and part-number label. For precision measurement applications, request calibration documentation and review the calibration interval. NI specifies a recommended 15-minute warm-up and a one-year calibration interval.
Related Products
The following products are relevant to PXI displacement measurement and sensor-conditioning systems. They have different functions and are not automatic replacements for the PXIe-4340.
- TB-4340 (784087-01) — Front-mount terminal block designed specifically for the PXIe-4340.
- PXIe-4330 — PXI Express strain/bridge measurement module for bridge-based sensor applications.
- PXIe-4331 — PXI Express strain measurement hardware for bridge sensor acquisition.
- PXIe-4339 — PXI Express bridge input module used in strain and related measurement systems.
- PXIe-4353 — PXI Express thermocouple input module for temperature measurement.
- SCXI-1540 — Legacy LVDT/RVDT signal-conditioning module; a different platform and not a direct PXIe-4340 substitute.
- PXI Express chassis — Required host platform for installing and operating the PXIe-4340.
- NI-DAQmx — NI driver software used to configure and acquire measurements from the module.
The TB-4340 is the model-specific terminal-block accessory. The other modules serve different sensor-measurement functions or use different hardware platforms.
Procurement and quality-control note: Specify both PXIe-4340 and part number 785068-01 when requesting a replacement. If the application requires a complete measurement connection, confirm whether the TB-4340 terminal block is also needed. For used or surplus hardware, request connector photographs, functional-test results, and calibration status. A module that enumerates in a PXI chassis has not necessarily passed sensor-excitation and measurement-accuracy testing.
