Description

The NI SCXI-1325 is a high-performance terminal block accessory designed by National Instruments (NI) to interface directly with the SCXI-1125 isolation amplifier module within the SCXI (Signal Conditioning eXtensions for Instrumentation) platform. As a critical front-end component in modular data acquisition (DAQ) systems, the NI SCXI-1325 provides a robust, screw-terminal connection point for field sensors—enabling precise measurement of thermocouples, low-voltage signals, and other analog inputs in both laboratory and industrial environments.

Each NI SCXI-1325 supports up to 8 differential input channels, featuring clearly labeled terminals for positive, negative, and shield connections. Integrated into its design is a built-in cold junction compensation (CJC) sensor, essential for accurate thermocouple readings by measuring the reference junction temperature at the terminal block itself. This eliminates errors caused by ambient fluctuations and ensures traceable temperature measurements across types J, K, T, E, R, S, and B. The terminal block mounts directly onto the front of the SCXI-1125 module, creating a seamless signal path from sensor to isolated amplifier without external patch cords or adapters.

Widely used in test & measurement, aerospace validation, power electronics characterization, and process monitoring, the NI SCXI-1325 enhances system reliability through secure screw-clamp terminals that resist vibration-induced loosening and support wire gauges from 16 to 28 AWG. Its compatibility with the broader SCXI ecosystem—including chassis, backplanes, and software tools like LabVIEW and Measurement & Automation Explorer (MAX)—makes it a versatile and trusted solution for engineers demanding signal integrity, ease of maintenance, and long-term scalability.

NI SCXI-1325 T

Technical Specifications

Product Model | SCXI-1325
Manufacturer | National Instruments (NI)
Product Type | SCXI Terminal Block / Connector Block
Compatible Module | SCXI-1125 Isolation Amplifier
Number of Channels | 8 differential inputs
Terminal Type | Screw-clamp (accepts 16–28 AWG wire)
Cold Junction Compensation | Integrated semiconductor sensor (±0.5°C accuracy)
Supported Sensor Types | Thermocouples (J, K, T, E, R, S, B), low-voltage DC signals
Isolation Reference | Matches SCXI-1125 (up to 250 V RMS channel-to-bus)
Operating Temperature | 0°C to +50°C
Mounting | Snap-on front panel of SCXI-1125 module
Dimensions | 14.3 cm × 7.1 cm × 2.5 cm (H×W×D)

Main Features and Advantages

Precision thermocouple interfacing with integrated CJC:
The NI SCXI-1325 eliminates one of the most common sources of temperature measurement error by embedding a high-stability cold junction compensation sensor directly at the point of signal termination. This ensures that the reference temperature is measured where the thermocouple wires connect—not remotely on the amplifier board—dramatically improving accuracy in dynamic thermal environments such as engine test cells or furnace monitoring.

Robust, service-friendly mechanical design:
Unlike spring-clamp or ribbon-cable interfaces, the NI SCXI-1325 uses industrial-grade screw terminals that provide gas-tight connections resistant to oxidation, corrosion, and mechanical shock. Each terminal is individually labeled and color-coded, reducing wiring mistakes during initial setup or sensor replacement. The snap-on mounting mechanism allows quick removal without tools—ideal for calibration cycles or module swaps in high-availability test labs.

Seamless integration with SCXI and LabVIEW ecosystems:
When paired with the SCXI-1125, the NI SCXI-1325 becomes part of a fully isolated, high-common-mode-rejection signal chain that protects sensitive DAQ hardware from ground loops and transient voltages. Configuration is automatic in NI MAX, and channel scaling for thermocouples is handled natively in LabVIEW, enabling rapid deployment of temperature monitoring applications without custom signal conditioning code.

Scalable architecture for multi-channel test systems:
Multiple NI SCXI-1325 blocks can be installed in a single SCXI chassis alongside other signal conditioning modules (e.g., strain, current, or RTD inputs), creating a unified, high-density acquisition front end. This modularity is especially valuable in aerospace structural testing or battery validation, where dozens of thermocouples must be monitored simultaneously with microvolt-level precision.

Application Field

In an automotive powertrain test cell, the NI SCXI-1325 interfaces with exhaust gas, coolant, and oil temperature sensors during engine durability runs. Its noise immunity ensures stable readings despite nearby ignition systems and high-current starter motors, while the CJC accuracy meets ISO 17025 calibration requirements for emissions certification.

At a renewable energy R&D lab, engineers use the NI SCXI-1325 to monitor thermal gradients across photovoltaic panels and battery packs under accelerated life testing. Paired with SCXI-1125’s 250 V isolation, the system safely measures floating potentials in series-connected cells without risking ground faults or measurement drift.

In aerospace structural validation, the NI SCXI-1325 terminates thermocouples embedded in composite wing sections during thermal vacuum chamber tests. The secure screw terminals withstand repeated thermal cycling from -55°C to +125°C, and the compact SCXI form factor allows dense channel packing within limited rack space—critical for full-scale aircraft testing campaigns.

NI SCXI-1325 T

Related Products

• SCXI-1125: Isolation amplifier module—SCXI-1325mounts directly onto this unit for signal termination

• SCXI-1308: General-purpose terminal block—lacks CJC, used with non-thermocouple SCXI modules

• SCXI-1313: High-voltage terminal block—for use with SCXI-1124 or similar ±100 V input modules

• SCXI-1520: Strain gauge terminal block—with built-in bridge completion and shunt calibration

• SCXI-1102: Multiplexed thermocouple input module—uses different terminal block (SCXI-1303)

• NI PXIe-4353: Modern thermocouple DAQ alternative—higher density, but lacks SCXI’s rugged modularity

• SCXI-1600: Compact SCXI chassis—supports oneSCXI-1325/SCXI-1125 pair for portable test setups