The NI SCXI-1121 is a 4-channel isolation amplifier module for SCXI chassis-based data acquisition systems. It delivers high-voltage isolation protection against common-mode voltages and ground loops while conditioning signals from voltage and current sensors in industrial environments. Each channel includes programmable excitation output (0 V to 10 V, up to 50 mA) with short-circuit protection, software-selectable gains from 1 to 100, and isolation ratings of 250 Vrms channel-to-earth and 250 Vrms channel-to-channel. The module achieves >80 dB CMRR at 60 Hz and >60 dB NMRR at 50/60 Hz, with low offset and gain drift across temperature.
Technical Specifications
Isolation and Protection
• Channel-to-Earth Isolation: 250 Vrms, CAT II
• Channel-to-Channel Isolation: 250 Vrms
• Maximum Common-Mode Voltage: 250 Vrms, CAT II
• Isolation Type: High-speed, low-leakage, capacitive isolation
Signal Conditioning
• Input Channels: 4 isolated channels
• Input Types: Voltage and current (configurable)
• Gain Settings: Software-selectable, 1 to 100
• Input Impedance: >1 MΩ
• Bandwidth: ≥50 kHz
• Excitation Output: 0 V to 10 V, up to 50 mA per channel with short-circuit protection
• Excitation Accuracy: ±5% of setting
• Excitation Stability: ±0.1% over 8 hours
Performance
• CMRR: >80 dB at 60 Hz
• NMRR: >60 dB at 50/60 Hz
• Offset Drift: <10 µV/°C
• Gain Drift: <100 ppm/°C
Interface and Power
• SCXI 37-pin connector
• Power: Supplied by SCXI chassis (+5 V, ±12 V, ±24 V)
– Compatibility & Integration
The module fits any SCXI chassis slot and integrates with SCXI-1000, SCXI-1001, and SCXI-1400 series systems. NI-DAQmx drivers support operation in LabVIEW, LabWindows/CVI, and NI Measurement & Automation Explorer (MAX).
