Description

The National Instruments SCXI-1125 is a high-density, isolated voltage input module designed for precision measurements in electrically noisy industrial environments. Part of NI’s SCXI (Signal Conditioning eXtensions for Instrumentation) platform, this 32-channel module delivers ±60V input range and 250 kHz aggregate sampling while providing 300Vrms channel-to-bus isolation—critical for protecting sensitive DAQ systems from ground loops and voltage transients. The SCXI-1125 integrates programmable gain amplifiers (1–1000 V/V), anti-aliasing filters, and per-channel calibration to achieve 16-bit resolution across diverse applications from motor power analysis to battery stack monitoring. Its unique floating common-mode architecture supports measurements with up to ±30V common-mode voltage, enabling direct connection to ungrounded sources like industrial sensors and three-phase systems. Compatible with NI DAQ boards via SCXI backplanes, the SCXI-1125 extends measurement integrity in automotive test cells, energy research labs, and production-line validation stations.

NI SCXI-1125

Technical Specifications

Main Features and Advantages

Advanced Signal Integrity: Optical isolation and guarded inputs eliminate ground loops while 60dB+ CMRR rejects line-frequency interference in motor drive and power converter testing.
Flexible Measurement Modes: Software-configurable as 32 single-ended or 16 differential channels with gains from 1–1000 V/V, adapting to mV-level sensor outputs or 100V bus measurements.
On-Demand Calibration: Built-in calibration multiplexer routes precision reference voltages to all channels, enabling automated self-calibration without disconnecting sensors.
High-Voltage Capability: Supports ±60V inputs (e.g., 48V battery stacks) and withstands ±30V common-mode offsets—ideal for floating measurements in ungrounded three-phase systems.
Thermal Resilience: Operates at -40°C to +70°C with <0>

Application Field

The SCXI-1125 excels in high-voltage multi-channel monitoring. Automotive engineers use it for electric vehicle battery stack voltage profiling and inverter efficiency testing. In energy, it captures solar array string voltages and wind turbine converter outputs. Industrial automation deploys it for PLC I/O validation and robotic arm motor current analysis (via shunt resistors). Power electronics labs leverage its isolation for switched-mode power supply ripple measurements. Research facilities apply it to electrochemical impedance spectroscopy and capacitor aging studies. Its common-mode tolerance makes it indispensable for transformer turns-ratio testing and floating ground measurements in industrial machinery.

Related Products

SCXI-1120: 8-channel isolated voltage input (±10V range).

SCXI-1141: Filter module for SCXI-1125 anti-aliasing enhancement.

SCXI-1349: Adapter cable for DAQ device integration.

NI 9229: C Series voltage input module (PXI alternative).

SCXI-1163: 64-channel relay multiplexer for test sequencing.

PCI-6251: M Series DAQ card for host control.

SCXI-1001: 12-slot chassis for system expansion.

NI SCXI-1125

Installation and Maintenance

Pre-installation preparation: Verify SCXI chassis compatibility and slot availability. Disconnect all field wiring before module insertion. Configure channel grounding (NI-DAQmx) to avoid common-mode violations. Use twisted-pair cables with shields terminated at source ends.
Maintenance recommendations: Perform annual self-calibration via NI-DAQmx. Quarterly clean backplane connectors with isopropyl alcohol. Monitor operating temperature; sustained >65°C requires airflow optimization. Replace every 5 years in high-surge environments (e.g., motor test stands).