Product Overview
The Allen-Bradley 1746-NI8 is a reliable analog I/O module designed for the SLC 500 system. It provides eight non-isolated differential input channels, configurable for voltage or current signals. This module addresses the need for precise analog signal conversion in time-sensitive industrial applications, ensuring high accuracy and fast response. As part of the SLC 500 series, it integrates seamlessly with fixed or modular controllers, making it a versatile choice for automation engineers.
Technical Specifications Breakdown
Key parameters for the 1746-NI8 are listed below for quick reference:
| Feature | Specification |
|---|---|
| Manufacturer | Rockwell Automation |
| Brand | Allen-Bradley |
| Part Number | 1746-NI8 |
| Series | SLC 500 |
| Module Type | Analog I/O Module |
| Backplane Current (5 Volts) | 200 milliamps |
| Backplane Current (24 Volts DC) | 100 milliamps |
| Input Signal Category | -20 to +20 mA (or) -10 to +10V dc |
| Bandwidth | 1-75 Hertz |
| Input Filter Frequencies | 1 Hz, 2 Hz, 5 Hz, 10 Hz, 20 Hz, 50 Hz, 75 Hz |
| Update Time | 6 milliseconds |
| Resolution | 16 bits |
| Step Response | 0.75-730 milliseconds |
| Conversion Type | Successive approximation, switched capacitor |
| Input Types, Voltage | 10V dc, 1-5V dc, 0-5V dc, 0-10V dc |
| Input Type, Current | 0-20 mA, 4-20 mA, 20 mA, 0-1 mA |
| Input Impedance | 250 Ohms |
| Backplane Power Consumption | 14 Watts Maximum |
| Data Format | Engineering Units, Scaled for PID, Proportional Counts (-32,768 to +32,767 range), Proportional Counts (User Defined Range, Class 3 only) |
| Chassis Location | Any I/O module slot except slot 0 |
| Applications | Combination 120 Volts AC I/O |
Industry Applications
This module is well-suited for process control environments requiring multiple analog inputs. For example, in a chemical plant, it can monitor temperature and pressure sensors across eight channels. Its fast update time of 6 milliseconds supports real-time adjustments, reducing downtime. In manufacturing, it handles voltage and current signals from transducers, enabling precise machine control. The wide bandwidth and filter options help reject noise in electrically noisy settings.
Installation & Setup Guidance
Install the 1746-NI8 in any I/O slot except slot 0 of the SLC 500 chassis. Use a removable terminal block with 18 positions for wiring. For voltage inputs, use Belden 8761 or similar cable with 14 AWG wire. Ensure loop impedance does not exceed 40 Ohms at the voltage source. Set input type via DIP switches on the module. The module supports single-ended or differential wiring for each channel.
Maintenance & Reliability
The module performs continuous autocalibration, reducing drift over time. Operate within 0 to 60 degrees Celsius for optimal performance. Periodically inspect the LED indicators—nine green status lights show channel and module health. Clean the terminal block connections to prevent signal degradation. The module is designed for Division 2 hazardous environments, so follow site safety protocols.
Compatibility & Integration
The 1746-NI8 works with SLC 5/01, 5/02, 5/03, 5/04, and 5/05 processors. SLC 5/01 supports Class 1 only; others support Class 1 and Class 3. Data formats include Engineering Units, Scaled for PID, and Proportional Counts. The module uses a successive approximation conversion method for reliable digital output.
Selection Guide & Purchasing Advice
When selecting the 1746-NI8, consider your input signal types—voltage or current—and required resolution. This module offers 16-bit resolution for high accuracy. For replacement or new installations, SpareTechPLC provides genuine Allen-Bradley parts with expert support. Verify lifecycle status before ordering.
Troubleshooting & Common Issues
If the module does not communicate, check the backplane current: 200 mA at 5V and 100 mA at 24V DC. Ensure the chassis slot is not slot 0. Verify DIP switch settings match your input type. If readings are noisy, adjust input filter frequencies (1-75 Hz) to match signal bandwidth. For persistent errors, inspect the removable terminal block for loose wires.
