NI SCXI-1104C

Electrical Parameters

• Total Input Channels: 32 fully differential input channels
• Maximum Input Signal Range: ±60 VDC, ±42 VAC peak / 30 VAC RMS
• Maximum Safe Damage Threshold: ±60 VDC or ±42 VAC peak for all input terminals
• Common-Mode Input Range: ±60 VDC relative to chassis ground (CGND)
• Input Impedance: 1 MΩ under normal powered state
• Onboard Filter: Independent 10 kHz low-pass filter per channel
• Isolation Rating: 250 V RMS channel-to-chassis electrical isolation
• Nonlinearity Error: ≤0.01% Full Scale Range (FSR)
• Offset Error: ≤300 µV after factory self-calibration; typical 1 mV pre-calibration
• Gain Error: ≤0.02% of reading after calibration; typical 0.1% pre-calibration

Environmental & Physical

• Operating Temperature: 0°C ~ 50°C
• Storage Temperature: -20°C ~ 70°C
• Relative Humidity: 10% ~ 90% non-condensing
• Module Form Factor: Standard SCXI single-width plug-in module

Functional Features

1. High Channel Density: 32 differential channels per single module, minimizing cabinet space for multi-point voltage measurement systems.
2. Wide Voltage Compatibility: Direct measurement of industrial medium-voltage signals without external voltage divider circuits.
3. Built-In Anti-Interference Design: Independent low-pass filtering for each channel to eliminate high-frequency electromagnetic noise; high common-mode rejection ratio suppresses ground loop interference in field wiring.
4. Programmable Gain Circuitry: Multi-level software-configurable gain to adapt to weak sensor signals and high-amplitude industrial voltage signals.
5. Full Software Controllability: All channel switching, gain adjustment and self-calibration operations are programmable via NI DAQmx driver and LabVIEW graphical programming.
6. System Scalability: Multiple SCXI chassis and SCXI-1104C modules can be cascaded to build large-scale distributed voltage monitoring systems.

Working Principle

Material & Structural Characteristics

1. Outer Housing: Aluminum alloy extruded shielded casing, surface matte oxidation treatment, excellent electromagnetic shielding performance, corrosion-resistant for industrial cabinet environments.
2. Circuit Substrate: High TG FR4 industrial PCB board, double-sided conformal coating to resist dust, moisture and mild chemical vapor in control cabinets.
3. Connector Hardware: Gold-plated copper alloy rear SCXI bus connector, gold-plated screw terminal mating interface for front terminal blocks, low contact resistance and anti-oxidation.
4. Internal Components: Low-noise precision operational amplifiers, polypropylene low-loss filter capacitors, high-voltage withstand isolation optocouplers, solid-state analog multiplexers.
5. Mechanical Structure: Standard single-slot SCXI chassis plug-in design, fixed by front panel locking thumbscrews; internal circuit boards are fixed with shock-absorbing silicone gaskets to resist cabinet vibration.

Installation Requirements

1. Chassis Compatibility: Must be installed into NI SCXI series chassis (SCXI-1000, SCXI-1001, SCXI-1000DC).
2. Power Supply Matching: The host SCXI chassis must provide rated DC operating power to the module; ensure chassis power load margin when installing multiple signal conditioning modules.
3. Wiring Standard: Use shielded twisted-pair wires for all field signal wiring; wire insulation voltage rating must exceed the maximum measured signal voltage (≥300 V Cat II insulation).
4. Terminal Block Matching: Must pair with SCXI series screw terminal blocks (SCXI-1300) for field signal wiring connection.
5. Environmental Installation Limits: Install inside sealed industrial control cabinet with dust filter; avoid direct exposure to water vapor, oil mist, corrosive gas; cabinet ambient temperature must stay within 0~50°C during continuous operation.
6. Ground Specification: Connect module chassis ground lug to cabinet protective earth ground with 1.5 mm² copper ground wire to maximize common-mode noise suppression.

Application Scenarios

1. Industrial automation multi-point voltage monitoring: motor winding voltage, power distribution cabinet secondary circuit voltage, PLC analog output signal collection.
2. Power system testing: substation secondary analog signal acquisition, generator voltage balance testing, battery pack multi-cell voltage monitoring.
3. Laboratory precision measurement: mechanical stress sensor voltage output, temperature transmitter analog signal, vibration sensor low-amplitude voltage measurement.
4. Transportation equipment testing: vehicle battery voltage array monitoring, train control cabinet analog signal acquisition.
5. Energy & mining: solar panel array voltage detection, underground equipment multi-point voltage safety monitoring.

Operation & Usage Precautions

1. Overvoltage Protection Warning: Never input signals exceeding ±60 VDC / ±42 VAC peak to input channels; overvoltage will permanently damage internal amplifier and multiplexer circuits.
2. Wiring Power Cut Rule: All field signal wiring installation, modification and disconnection must be completed after cutting off both the SCXI chassis power and field equipment power to avoid electric shock and module circuit burnout.
3. Calibration Cycle: Perform full-channel self-calibration via DAQmx driver every 6 months to maintain measurement accuracy; recalibration is mandatory after long-term high-temperature operation or severe electrical surge impact.
4. Vibration Prevention: Avoid installing the chassis in areas with continuous strong mechanical vibration (e.g., near large compressors, forging equipment); vibration will loosen internal circuit solder joints and degrade measurement stability.
5. Moisture Control: If the control cabinet operates in high-humidity environments (RH >85%), install cabinet dehumidifier to prevent PCB board condensation and short-circuit failure.
6. EMI Interference Mitigation: Separate high-power AC power cables and weak analog signal wiring inside the cabinet with metal shielding partitions; all shielded cable shielding layers must be single-point grounded at the cabinet earth bar.