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Phone: +86 16626708626Description
Real-World Use & Application Scenarios
In industrial automation, accurate analog output control is essential for precise modulation of process variables such as flow, pressure, temperature, and level. The Allen-Bradley 1746-NO8I module is well-suited to factory automation, batch processing, and continuous control scenarios commonly found in industries like chemical processing, pharmaceuticals, water treatment, and manufacturing. This module enables the SLC 500 system to control actuators, valves, and variable frequency drives that require current-based signals.
Particularly useful where multiple analog outputs are needed within compact PLC racks, the 1746-NO8I supports applications requiring up to eight current outputs simultaneously. It helps address challenges such as minimizing signal noise, providing fast response for process adjustments, and enabling fine control resolution to improve product quality and process efficiency. Integrated advanced features simplify calibration, scaling, and diagnostic processes, reducing maintenance costs and downtime.
Product Introduction & Positioning
The Allen-Bradley 1746-NO8I is an 8-channel analog current output module designed for the SLC 500 series PLCs. It generates 4 to 20 mA or configurable current signals that interface directly to industrial output devices. Its high density—eight output channels in a single slot—maximizes I/O capacity, making it practical for space-constrained control environments.
Engineers value the 1746-NO8I for its high 16-bit resolution output, fast update rates (as fast as 5 ms for Class 1 operation), and ability to produce multiple output formats suitable for PID control and proportional scaling. The module integrates tightly with RSLogix 500 software for programming and monitoring, supporting user-defined engineering units and automatic diagnostics, thus enabling accurate and flexible control solutions.
- 1746-NO8I
- 1746-NO8I
Key Technical Features & Functional Benefits
The 1746-NO8I provides eight independent current output channels with an output range configurable from 0 to 21.5 mA, supporting common industrial standards. Its 16-bit resolution ensures smooth analog signal gradation, enhancing control finesse for sensitive applications. The module offers fast step response times of approximately 1 ms from 0 to 95% full scale, enabling quick actuator adjustments.
Integrated diagnostics include output clamping, limit alarms, and channel fault detection, improving safety and reliability. The module supports multiple data formatting options, including scaled engineering units and proportional counts, simplifying integration with complex control algorithms. Its backplane current consumption is minimal, with 120 mA at 5 VDC and 250 mA at 24 VDC, contributing to efficient power management.
Stable operation within an ambient temperature range of 0 to 60 °C and features like automatic self-calibration enhance long-term reliability in industrial environments. The module’s robust design and industry certifications permit its use in diverse process control systems requiring precise analog outputs alongside digital control.
Detailed Technical Specifications
| Parameter | Value |
|---|---|
| Model | 1746-NO8I |
| Brand | Allen-Bradley |
| Product Type | 8-Channel Analog Output Module |
| Output Channels | 8 |
| Output Current Range | 4 to 20 mA; 0 to 20 mA; 0 to 21 mA; 0 to 21.5 mA |
| Resolution | 16 bits |
| Update Time | Class 1: 5 ms; Class 3: 10 ms |
| Step Response | 1 ms (0 to 95% full scale) |
| Backplane Current (5 V) | 120 mA |
| Backplane Current (24 V) | 250 mA |
| Operating Temperature | 0 to 60 °C |
| Wire Size | Two 14 to 24 AWG wires per terminal |
| Data Formats | Scaled engineering units, PID scaling, proportional counts |
| Dimensions (Typical) | Fits 1 slot in SLC 500 chassis |
Related Modules or Compatible Units
Allen-Bradley 1746-NO4I – Lower density 4-channel analog output module.
Allen-Bradley 1746-NI8 – Analog input module with 8 channels for complementary sensor data acquisition.
Allen-Bradley 1746-NO8V – Voltage output version providing 8 voltage output channels.
Allen-Bradley 1756-IF16 – Analog input module for the ControlLogix system, complementing the SLC output modules.
Allen-Bradley 1746-OB16 – Digital output module supporting discrete control signals.
Installation Notes & Maintenance Best Practices
Install the 1746-NO8I module in an SLC 500 chassis with attention to ambient temperature limits and adequate ventilation. Confirm power supply voltages align with SLC 500 system specifications. Use shielded or twisted-pair wiring within the advised AWG range for load connection to minimize noise and ensure signal integrity.
Maintenance includes periodic verification of output accuracy and diagnostics status through RSLogix 500 or PLC monitoring software. Check for loose connections and signs of corrosion or damage at output terminals. Firmware updates and configuration backups should be performed regularly to sustain precision and system security. Keep modules free from dust buildup to maintain thermal efficiency.
