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- Key Technical Specifications
| Parameter | Specification |
| Part Number | 776577-04C |
| Input Channels | 32 Differential |
| Attenuation Ratio | 10:1 fixed attenuation stage |
| Maximum Voltage Range | ±42 V DC or AC peak |
| Low-Pass Filter Cutoff (-3dB) | 10 kHz (C-suffix designated filter frequency) |
| Amplifier Gain | 1 (net module gain 0.1 due to 10:1 attenuation) |
| Filter Type | 3-pole low-pass RC filter |
| Multiplexer Scan Rate | Up to 333 kS/s (depending on host DAQ card) |
| Compatible Terminal Blocks | SCXI-1300, SCXI-1303, SCXI-1308 |
| Overvoltage Protection | ±42 V powered ON; ±42 V powered OFF |
| Power Requirements | +5 V DC (20 mA), ±15 V DC (150 mA) from SCXI chassis backplane |
| Operating Temperature | 0 to 50°C (32 to 122°F) |
- Product Introduction
The National Instruments SCXI-1104C is a 32-channel differential analog input signal conditioning module designed for high-density voltage measurements in SCXI chassis system architectures. Built specifically for medium-voltage data acquisition applications, it features a 10:1 input attenuation network that scales signals up to ±42 V DC/AC down to standard ±4.2 V levels suitable for high-speed E/M/X Series PXI or PCI DAQ cards.
Equipped with factory-tuned 10 kHz 3-pole low-pass filters per channel, the SCXI-1104C eliminates high-frequency electrical noise and antialiasing artifacts in high-speed transducer, automotive battery, and power rail test benches. Automation engineers specify the “C” variant when higher measurement bandwidth is required compared to standard 4 Hz filtered variants.
- Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
| Module not detected in NI MAX | Chassis backplane fuse blown or module address jumper mismatch | ✅ High | Re-seat module; verify SCXI chassis power LED and run self-test in NI MAX | Confirm SCXI ID jumpers match software configuration. Verify power rail voltages from SCXI chassis backplane. |
| Inaccurate Voltage Readings (e.g., 10x smaller) | Software scaling missing 10:1 attenuation factor compensation | ❌ Low | Measure raw voltage at terminal block vs. reported software channel value | Enable automatic SCXI module scaling in NI-DAQmx or multiply channel raw voltage scaling by 10.0 in custom code. |
| Severe Signal Attenuation above 2 kHz | Expecting full bandwidth, but signal is affected by 10 kHz RC roll-off | ✅ High | Inject a 1 kHz vs 15 kHz sine wave using a signal generator and measure output | Verify signal frequency is well within the 10 kHz 3dB passband limit. If higher bandwidth is needed, an unfiltered card is required. |
| Channel Crosstalk / Floating Readings | Open input terminal or ungrounded differential signal source | ❌ Low | Place a 10 kΩ bias resistor between (-) terminal and chassis ground for floating sources | Connect signal ground references properly or attach an external SCXI-1300 terminal block to ground cold junctions. |
SCXI-1104C
SCXI-1104C
- Frequently Asked Questions (FAQ)
Q: What is the primary functional difference between the SCXI-1104 and the SCXI-1104C?
A: The difference lies in the low-pass filter cutoff frequency. The standard SCXI-1104 features a 4 Hz filter designed for slow DC temperature and voltage monitoring, while the SCXI-1104C features a 10 kHz filter designed for higher-speed transient voltage captures, dynamic sensor sampling, and noise-filtering applications.
Q: Can I measure signals higher than ±42 V DC with this module?
A: No. Exceeding ±42 V DC or AC peak will saturate the attenuation stage and risks exceeding internal overvoltage limits. For higher voltage applications (e.g., 300 V or 600 V channel-to-channel isolation), you should select isolated signal conditioning modules like the SCXI-1125 or SCXI-1120.
Q: Which terminal block should I select for screw-terminal wiring?
A: The most common terminal block for the SCXI-1104C is the SCXI-1300 standard screw terminal block. If you are measuring current signals via external precision shunts, use the SCXI-1308. For thermocouple measurements mixed with voltage signals, select the isothermal SCXI-1303.
Q: Is the SCXI-1104C hot-swappable in a powered SCXI chassis?
A: No. Always switch off power to the SCXI chassis and the connected host DAQ board before inserting or removing the module. Hot-swapping risks damaging the backplane multiplexer switches and host PCI/PXI card analog inputs.
Q: How do you verify the performance of surplus NI SCXI modules before dispatch?
A: Every unit undergoes a strict 5-step SOP quality inspection. We clean all backplane contacts, insert the module into a live SCXI-1000 chassis paired with an NI DAQ card, feed precise ±40 V precision DC calibration signals across all 32 channels, verify 10 kHz bandwidth filtering limits, and perform a 500 V Megger insulation check prior to ESD packaging.
