Product Overview
The Allen-Bradley 1746-NO4I is a precision analog output module from the SLC 500 series, designed for industrial automation systems requiring reliable current output control. This module provides four (4) current output channels with a range of 0 to +20 mA, making it ideal for driving modulating instruments such as valves, actuators, and variable frequency drives. Built by Rockwell Automation, the 1746-NO4I integrates seamlessly with SLC 500 fixed or modular hardware, offering engineers a robust solution for analog signal generation in process control, manufacturing, and building automation.
Technical Specifications Breakdown
Key parameters for the 1746-NO4I are listed below for quick reference:
| Feature | Specification |
|---|---|
| Manufacturer | Rockwell Automation |
| Brand | Allen-Bradley |
| Part Number | 1746-NO4I |
| Series | SLC 500 |
| Module Type | Analog Output Module |
| Outputs | Four (4) |
| Output Current Range | 0 to +20 mA |
| Full Scale Output | 21 mA |
| Overrange Capability | 5% (0 to +21 mA - 1 LSB) |
| Current Output Coding | 0 to +32764 |
| Update Time | 512 microseconds |
| Resolution | 14 bits |
| Step Response | 2.5 milliseconds |
| Backplane Current (5 Volts) | 55 milliamps |
| Backplane Current (24 Volts DC) | 195 milliamps |
| Ambient Operating Temperature | 0 to 60 degrees Celsius |
| UPC | 10662073735912 |
Industry Applications
The 1746-NO4I excels in applications requiring precise current output for modulating control. In process industries, it can drive I/P transducers to position control valves based on PID controller commands, ensuring accurate flow or pressure regulation. In manufacturing, its 14-bit resolution and 512 µs update time support high-speed analog signal generation for servo drives or actuator control. The module's 5% overrange capability (0 to +21 mA - 1 LSB) provides additional headroom for diagnostic or safety shutdown signals, reducing the risk of system trips during transient conditions.
Installation & Setup Guidance
When integrating the 1746-NO4I into an SLC 500 system, ensure the backplane provides adequate current: 55 mA at 5 VDC and 195 mA at 24 VDC. The module features an embedded selector switch for power supply source—choose internal backplane power or external 24 VDC supply (24 ±10% at 195 mA max). For wiring, use shielded communication cable (e.g., Belden 8761) with short lengths to minimize noise. The removable terminal block simplifies wiring and module replacement. Verify the output load range is within 0 to 500 ohms and maximum load reactance of 100 µH to maintain signal integrity.
Maintenance & Reliability
To ensure long-term reliability, operate the module within its ambient temperature range of 0 to 60 degrees Celsius. Periodically inspect the backplane connections and verify that the backplane current draw remains within specifications (55 mA at 5 VDC, 195 mA at 24 VDC). The module's factory-calibrated outputs and 14-bit resolution via R-2R ladder conversion provide stable performance, but environmental factors like humidity (5 to 95% non-condensing) should be monitored. Regular checks of the LED status indicator can help identify early faults.
Compatibility & Integration
The 1746-NO4I is compatible exclusively with the SLC 500 platform, including both fixed and modular hardware styles. It fits into any 1746 chassis and communicates via the backplane. The module uses a 16-bit 2's complementary binary format for data exchange with the controller. For PID control applications, the analog output can represent the Control Output (CO) variable, while manual loading stations can use it for operator commands. The module also supports signal re-transmission to multiple devices for indication or data logging.
Selection Guide & Purchasing Advice
When selecting the 1746-NO4I, consider your system's output requirements: four current outputs with a 0 to +20 mA range. If you need voltage outputs, consider other SLC 500 analog modules. For applications requiring high accuracy, the 14-bit resolution and 512 µs update time deliver reliable performance. SpareTechPLC stocks the 1746-NO4I and can advise on lifecycle status and availability. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Troubleshooting & Common Issues
If the module fails to produce output, first check the backplane power: ensure the 5 VDC and 24 VDC currents are within limits (55 mA and 195 mA respectively). Verify the power supply source selector switch is set correctly—internal or external 24 VDC. If outputs are inaccurate, confirm the load resistance is between 0 and 500 ohms and that the cable is shielded and properly grounded. The LED status indicator can help diagnose communication faults; if off, check backplane seating. For persistent issues, consult the SLC 500 manual for detailed diagnostics.
