Product Introduction
The Allen-Bradley 1791-0B16 is a discrete DC Block I/O module from the 1791 series, designed to serve as a remote I/O device in industrial control systems. It integrates a programmable controller interface, power supply, I/O connections, and signal-generating circuitry into one compact unit. This module communicates via Universal Remote I/O, making it ideal for distributing I/O at remote locations while reducing wiring and enclosure costs.
With 16 output channels and a 24V DC nominal voltage, the 1791-0B16 delivers reliable performance for applications such as packaging, material handling, and operator interface panels. Its compact size and flexible mounting options allow installation in smaller, less expensive enclosures, providing a cost-effective solution for distributed control.
Technical Specifications
The following table summarizes the key technical parameters of the Allen-Bradley 1791-0B16, sourced directly from the manufacturer's documentation.
| Specification |
Value |
| Manufacturer |
Allen-Bradley (Rockwell Automation) |
| Product Line |
1791 Block I/O |
| Part Number |
1791-0B16 |
| Category |
PLCs |
| Outputs per Block |
16 |
| Output Voltage Range |
10-30V DC |
| External Power |
19.2-30V DC |
| Minimum On-state Current |
1mA per output |
| Maximum On-state Voltage Drop |
1V @ rated current |
| Output Signal Delay |
0.5ms on; 1.0ms off (max.) |
| Weight |
1.00 lbs (0.45 kg) |
| Dimensions (H x W x D) |
6.95 x 2.7 x 3.85 in. |
| Current Requirement |
300mA |
| Output Current Rating (Vertical Mount) |
500mA at 60 °C |
| Output Current Rating (Horizontal Mount) |
250mA at 60 °C |
| Maximum Power Dissipation |
12.5W |
| Maximum Thermal Dissipation |
43 BTU/hr |
| Maximum Off-state Leakage Current |
0.5mA |
| Communication |
Universal Remote I/O |
| Wiring |
2 mm² (14 AWG) solid wire, max insulation 3/64 in. |
These specifications ensure the 1791-0B16 provides consistent switching performance with minimal signal delay, making it suitable for high-speed discrete control applications.
Industry Applications
The Allen-Bradley 1791-0B16 excels in environments where remote I/O distribution is essential. Its robust design and flexible mounting make it a preferred choice for:
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Packaging machinery: Controls solenoids and actuators with fast 0.5ms on-delay, ensuring precise timing in high-cycle operations.
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Material handling systems: Distributes I/O near conveyors and sorters, reducing long cable runs and simplifying maintenance.
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Operator interface panels: Provides reliable output control for indicator lights and pushbuttons, enhancing operator feedback.
By placing the 1791-0B16 close to the field devices, you cut wiring costs and improve signal integrity—a key advantage in large plants.
Installation & Setup Guidance
Proper installation maximizes the reliability of the Allen-Bradley 1791-0B16. Follow these guidelines:
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Mounting: The module can be mounted horizontally or vertically, but vertical mounting is recommended. Vertical orientation allows higher output current (500mA vs. 250mA at 60°C).
-
Termination: If this is the last block I/O module in a series, install a termination resistor to ensure proper communication.
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Wiring: Use 2 mm² (14 AWG) solid wire with maximum insulation of 3/64 in. for power and I/O connections. Ensure secure terminations to prevent intermittent faults.
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Fusing: No external power fusing is required—the 1791-0B16 has built-in internal fusing for protection.
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Switch settings: Configure the two switch assemblies for starting I/O group, I/O rack number, communication rate, last state, and last chassis as per your system layout.
Always power down before making connections and verify polarity to avoid damage.
Maintenance & Reliability
The Allen-Bradley 1791-0B16 is designed for long service life, but routine checks help prevent downtime. Inspect the module quarterly for:
-
Indicator status: The 1 COMM, 1 STATUS, and 16 I/O Status LEDs provide real-time diagnostics. Any unexpected LED patterns signal a fault.
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Terminal strip integrity: Removable terminal strips simplify replacement—verify screws are tight and contacts are clean.
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Environmental conditions: Keep the enclosure clean and within temperature limits to maintain output current ratings.
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Leakage current: Monitor off-state leakage (max 0.5mA) to ensure outputs de-energize properly.
These simple steps extend module life and reduce the total cost of ownership.
Compatibility & Integration
The 1791-0B16 integrates seamlessly with Rockwell Automation controllers. It is compatible with:
- PLC-2, PLC-3, PLC-5/250, and PLC-5 series programmable controllers
- SLC 5/02 series modular controllers
Using Universal Remote I/O, the module communicates over a single cable, reducing wiring complexity. Its 16 discrete outputs can drive solenoids, contactors, and indicator lights directly, simplifying system design.
Buying Guide
Before purchasing an Allen-Bradley 1791-0B16, verify your system's communication protocol and controller compatibility. Confirm the required output voltage range (10-30V DC) matches your field devices. Also, check the mounting orientation to ensure you achieve the desired output current. For genuine parts and reliable delivery, consider PLC Source PRO as your supplier—they specialize in industrial automation spares and offer quality assurance.