Overview
The Allen-Bradley 1746-NI8 /A is a single-slot analog input module designed for the SLC 500 family of programmable controllers. This 8-channel module converts analog signals into digital values for process monitoring, closed-loop control, and data acquisition applications. Built by Rockwell Automation, the 1746-NI8 provides reliable, high-resolution signal conditioning in a compact form factor.
Key Features
- 8 independent input channels with per-channel voltage/current selection using embedded DIP switches
- 16-bit analog-to-digital conversion with 1 mV or 1 µA input resolution
- Flexible input ranges: ±10V DC, 0–10V DC, 0–5V DC, 1–5V DC, 0–20mA, 4–20mA, ±20mA
- Isolated backplane with common-mode rejection of 75 dB at DC and 100 dB at 50/60 Hz
- Software-configurable digital filter with programmable low-pass frequencies (1–75 Hz bandwidth)
- Removable 18-position terminal block for easy wiring and field maintenance
- Status display with nine LED indicators for channel diagnostics
- Single/differential channel wiring support for application flexibility
Technical Specifications
- Input Channels: 8 non-isolated differential
- Input Voltage: ±10V DC, 0–10V DC, 0–5V DC, 1–5V DC (software-selectable per channel)
- Input Current: 0–20mA, 4–20mA, ±20mA (software-selectable per channel)
- Resolution: 16-bit A/D conversion
- Update Time: 6 milliseconds
- Bandwidth: 1–75 Hz (configurable via digital filter)
- Backplane Current: 200 mA @ 5V DC; 100 mA @ 24V DC
- Power Dissipation: 1 W @ 5V DC; 2.4 W @ 24V DC
- Isolation Voltage: 750V DC, 530V AC (60-second test)
- Mounting: Single I/O module slot (any slot except Slot 0)
- Operating Temperature: 0–60°C
- Weight: 0.55 lbs
- Terminal Block: 18-position removable screw-terminal
Typical Applications
The 1746-NI8 is engineered for industrial processes requiring precise analog signal measurement and real-time control:
- Process monitoring — pressure, temperature, level, and flow measurement from 4–20mA transmitters
- Closed-loop control — feedback regulation for proportional valves and variable-frequency drives
- Data logging — sensor signal acquisition for industrial IoT and condition monitoring systems
- Quality assurance — analog input from test equipment and quality control instrumentation
- Motion control integration — analog signals from encoders, load cells, and potentiometers
Compatibility & Replacements
Compatible With
- SLC 5/01, SLC 5/02, SLC 5/03, SLC 5/04, and SLC 5/05 processors
- SLC 500 fixed and modular chassis configurations
- SLC 500 I/O slots 1–30 (any slot except Slot 0, reserved for processor modules)
- Class 1 and Class 3 operation modes (configuration-dependent)
- Connected through standard SLC 500 I/O module backplane communication
Replaces / Drop-In Replacement For
- Allen-Bradley 1746NI8 (earlier revision without the “/A” suffix)
- Functionally equivalent to the 1746-NI4 (4-channel variant) in mixed-channel applications
Works With
- RSLogix 500 programming software for module configuration and I/O mapping
- Studio 5000 (via legacy SLC 500 import) for modernized environments
- SLC 500 analog I/O data formatting: Engineering Units, Scaled-for-PID, Proportional Counts (–32,768 to +32,767), user-defined ranges (Class 3)
- All SLC 500 communication networks and gateway modules
