Overview
The Allen-Bradley 1746-NI4 is a proven analog input module for the SLC 500 control platform. This 4-channel module delivers high-resolution analog acquisition for temperature transmitters, pressure sensors, level transducers, and other 0–10V or 4–20 mA process instruments. With user-selectable voltage or current input configuration per channel, the 1746-NI4 remains a trusted choice in legacy and installed base automation systems.
Key Features
- Four differential analog input channels — each independently configurable for voltage (±10V DC) or current (±20 mA) signals
- 14-bit resolution with 0.05% non-linearity — high fidelity for precision process monitoring
- ±0.384% full-scale accuracy across operating temperature 0°C to 60°C
- Removable terminal block — simplifies wiring and replacement without removing module from chassis
- Single-slot mounting — fits any SLC 500 I/O chassis (fixed or modular) without processor interference
- Noise filtering and shielding — designed for industrial EMI environments
Technical Specifications
- Analog Input Channels: 4 differential, non-isolated
- Voltage Input Range: ±10 V DC (−1 LSB)
- Current Input Range: ±20 mA nominal, ±30 mA maximum
- Resolution: 14 bits (305.176 µV/LSB for voltage, 1.22070 µA/LSB for current)
- Input Impedance: 1 MΩ (voltage), 250 Ω (current)
- Overall Accuracy: ±0.384% of full scale (0°C–60°C)
- Update Time: 512 microseconds per channel
- Bandwidth: 10 Hz
- Operating Temperature: 0°C to 60°C (32°F to 140°F)
- Backplane Power (5V): 25 mA
- Mounting: Single-slot SLC 500 chassis (any slot except processor)
- Series: Series A / Series B compatible
- Certifications: UL listed, CSA approved, CE compliant, NEMA enclosure rated
Typical Applications
The 1746-NI4 is used across a wide range of process industries:
- Temperature monitoring — RTD transmitters, thermocouple linearizers providing 4–20 mA output
- Pressure control — pressure transducers outputting 0–10V or 4–20 mA
- Level measurement — capacitive and ultrasonic level transmitters
- Flow measurement — turbine and electromagnetic flowmeter signal acquisition
- Batch and continuous processing — chemical, food, water treatment, and HVAC systems
- Legacy system support — field-proven in installed base equipment requiring long-term spares availability
Compatibility & Replacements
The 1746-NI4 plugs directly into any SLC 500 fixed or modular I/O chassis (except the processor slot). It is backward-compatible with Series A and forward-compatible with Series B hardware. For modern analog acquisition, Rockwell Automation offers the CompactLogix or ControlLogix platform with integrated analog I/O modules or distributed remote I/O blocks; however, the 1746-NI4 remains preferred for drop-in replacement and legacy system continuity. Third-party modules from Siemens (S7-1200/1500 TIA Portal) or Mitsubishi (MELSEC iQ-F) require full system migration and programming redesign. Direct replacement within the SLC 500 family: use 1746-NI4 /A (Series A) or 1746-NI4 /B (Series B) depending on your chassis revision.
