Product Overview
8-Channel Isolation Amplifier for NI SCXI Systems - Programmable Gain, 300 Vrms Channel Isolation
Condition
Used, sourced from a government research facility. Evaluation: Visual inspection only. Function testing not performed. Metal housing shows moderate surface scratching and light scuffs consistent with lab use. Front panel markings, NI label, gold-pin backplane connector, and multi-pin input connectors are intact. Serial no. 132E886, part no. 185959F-01, made in Hungary. Captive panel screws and thumbscrews present.
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Product Overview
National Instruments SCXI-1125 is an 8-channel isolation amplifier module for NI SCXI signal conditioning systems. It accepts millivolt, volt, and current signals including 4-20 mA loops and thermocouple inputs, conditions each channel independently with programmable gain and lowpass filter settings, and delivers isolated analog output to a connected DAQ device. Each channel provides 300 Vrms working isolation both channel-to-channel and channel-to-earth, eliminating ground loops and protecting downstream hardware from high common-mode voltages. The SCXI-1125 replaces the jumper-configured SCXI-1120 with fully software-controlled gain and filter settings, making it compatible with LabVIEW, LabWindows/CVI, and other NI application environments via NI-DAQ or NI-DAQmx drivers.
Key Features
- 8 isolated analog input channels with independent per-channel configuration
- 300 Vrms working isolation - channel-to-channel and channel-to-earth
- Programmable gain: 12 settings from 1 to 2000
- Programmable lowpass filter per channel: 4 Hz or 10 kHz
- Input range: ±2.5 mV to ±5 V standard; up to ±300 V with SCXI-1313 terminal block
- Output range: ±5.0 V
- Cold-junction compensation channel included for thermocouple measurements
- Supports multiplexed and parallel output modes
- CE certified, double insulated, Category II
- Compatible with SCXI-1000 and SCXI-1001 chassis; requires NI-DAQ 6.6 or NI-DAQmx 9.0 or later
Applications
- R&D lab engineer connecting thermocouples and millivolt sensors to a multi-slot SCXI chassis, configuring per-channel gain in LabVIEW to pull clean signals from electrically noisy test fixtures
- Process control technician wiring 4-20 mA current loops from plant-floor transducers through the SCXI-1125 to isolate the DAQ system from high common-mode voltages on industrial equipment
- University researcher building a multi-channel data acquisition setup where ground loop elimination is critical to measurement accuracy across dissimilar sensor types
- System integrator replacing a failed SCXI-1120 in an existing NI chassis - the SCXI-1125 is the jumperless, software-configured successor with backward compatibility
Frequently Asked Questions
What chassis does the SCXI-1125 require?
The SCXI-1125 requires a National Instruments SCXI chassis such as the SCXI-1000 or SCXI-1001. It also requires a compatible NI DAQ device and NI-DAQ driver software version 6.6 or higher, or NI-DAQmx 9.0 or later.
Is a terminal block included?
No terminal block is included. The module ships as shown. Compatible terminal blocks include the SCXI-1313, SCXI-1327, and TBX-1316 - these are required separately if extended input ranges beyond ±5 V are needed.
How does the SCXI-1125 differ from the SCXI-1120?
The SCXI-1125 is the jumperless successor to the SCXI-1120. Where the SCXI-1120 uses physical jumpers for gain and filter configuration, the SCXI-1125 is fully software-programmable. The SCXI-1125 also provides 300 Vrms working isolation versus 250 Vrms on the SCXI-1120.
What software is required to configure this module?
The SCXI-1125 is configured through NI-DAQ or NI-DAQmx drivers and an application development environment such as LabVIEW, LabWindows/CVI, BridgeVIEW, or Visual Basic with ComponentWorks. The module is not self-configuring and requires software to set gain and filter parameters.
Does this module handle thermocouple inputs?
Yes. The SCXI-1125 includes a cold-junction compensation channel for thermocouple measurements and accepts the millivolt-level signals thermocouples produce within its standard programmable input range.
The SCXI-1125 earned its place in government labs by keeping measurement chains honest when voltages got complicated. That capability is still intact - ready for the next chassis it calls home.
