Description

Key Technical Specifications

Product Model: SCXI-1104C
Manufacturer: National Instruments
Product Category: Signal Conditioning Module
Input Configuration: 32 Single-Ended or 16 Differential Channels
Input Range: ±60 VDC / ±42 VAC (42 Vp-p)
Fixed Gain: 0.1 (Attenuation for high-voltage scaling)
Input Filter: Two-pole RC Butterworth, 10 kHz Cutoff (-3dB)
Step Response: Settles to 0.1% in 200 ms, 0.01% in 1 ms
Input Impedance: 1 MΩ
Coupling: DC Only (Hardware AC coupling requires external capacitor)
Operating Temp: 0°C to 50°C (20-min warmup recommended)

Product Introduction

You are trying to measure a ±40VDC rail in a power supply test, and your DAQ card is screaming about overvoltage. The NI SCXI-1104C is the exact signal conditioning module designed to solve this. It sits between your high-voltage field wiring and your sensitive DAQ digitizer, providing galvanic isolation and scaling the voltage down via a fixed 0.1 gain. With 16 differential channels (or 32 single-ended), it handles medium-voltage signals up to ±60VDC while rejecting common-mode noise that would otherwise destroy your measurements.

Why not just use a voltage divider? Because you need isolation and filtering. The SCXI-1104C includes a 10kHz two-pole Butterworth lowpass filter that kills high-frequency switching noise from PWM power supplies. Bottom line—if you are measuring anything above ±10V and need differential isolation, this is your module. Just don’t try to measure thermocouples or millivolt signals with it; the fixed 0.1 gain means you’ll lose all your resolution below ~50mV.

Troubleshooting Quick Reference

Readings Stuck at Max/Min: 90% chance of overvoltage. Verify signal never exceeds ±60VDC or ±42VAC. Exceeding these limits damages the input stage. Measure with a DMM first.
Noisy / Erratic Readings: 80% probability of missing ground reference or floating signal. SCXI-1104C is DC-coupled; floating signals will drift. Tie signal ground to module AGND via pin 1, 2, 4, or 19.
Signal Attenuated Unexpectedly: 95% chance you forgot the 0.1 fixed gain. Multiply your raw reading by 10. This is not a bug—it’s hardware scaling.
High-Frequency Noise Not Filtered: 70% likelihood signal exceeds 10kHz cutoff. The Butterworth filter rolls off at -3dB at 10kHz. If you need 40kHz gate drive waveforms, this is the wrong module.
Module Not Detected in MAX: 85% chance of backplane seating or ribbon cable issue. Reseat module. Verify SCXI chassis power. Check DAQ board compatibility (e.g., M-Series, E-Series).

NI SCXI-1104C

Application Scenarios & Pain Points

PWM Power Supply Testing: Measuring gate drive waveforms and DC bus voltages in ATE systems. Pain point: Switching noise corrupts measurements. The 10kHz Butterworth filter cleans up the signal while the 200ms settling time handles step changes.
Industrial Motor Drives: Monitoring DC link voltages and phase-to-phase AC signals. Pain point: High common-mode voltage destroys DAQ cards. The SCXI-1104C’s differential isolation protects your digitizer.
Automotive Battery Test Stands: Logging cell voltages up to ±60V in series stacks. Pain point: Single-ended measurements pick up ground bounce. Differential configuration rejects common-mode noise across the stack.

Compatible Replacement Models

✅ Drop-in Replacement: . Exact same revision. Same 10kHz filter, same 0.1 gain. Slide-in and go.
⚠️ Software Compatible: SCXI-1104 776572-04. Same family, but 2Hz cutoff filter (not 10kHz). Only substitute if your signal is <2Hz. Otherwise, you’ll filter out your signal. Expect 1-2 hours validation.
❌ Hardware Incompatible: SCXI-1102B. Same form factor, but programmable gain (up to 100x) for low-voltage signals. Will NOT handle ±60VDC. Do not substitute for high-voltage applications. PXI-6251 is a DAQ card, not a signal conditioner.