Product Overview
The Allen-Bradley 1791-16AC is a block I/O module engineered for Remote I/O architectures. It integrates a power supply, PLC interface, I/O connections, and signal conditioning circuitry into one compact unit. With sixteen 120VAC input channels and sixteen 120VAC output channels, this module simplifies wiring and reduces panel space, making it a dependable choice for distributed control systems.
Key Features & Benefits
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Complete I/O solution: Combines input, output, and communication functions in a single block.
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Remote I/O adapter mode: Connects directly to a Remote I/O scanner, enabling daisy-chain topology.
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Flexible mounting: Supports vertical or horizontal orientation to suit various enclosure layouts.
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Robust electrical isolation: 500VAC between power supply and RIO, 1250VAC between I/O groups and logic.
Technical Specifications
| Specification |
Value |
| Manufacturer |
Allen-Bradley |
| Product Type |
Block I/O |
| Product Line |
1791 Block I/O |
| Part Number |
1791-16AC |
| UPC |
612598124749 |
| Weight |
2.00 lbs (0.91 kg) |
| Inputs per Block |
16 |
| Outputs per Block |
16 |
| No. of Groups |
2 groups of 8 |
| Nominal Input Voltage |
120VAC |
| Input On-state Voltage Range |
79 to 132 Volts AC |
| Input On-state Current |
12.3 mA at 132 Volts maximum |
| Input Off-state Voltage |
35 Volts maximum |
| Input Off-state Current |
2.3 mA minimum |
| Nominal Input Current |
11 mA |
| Output Voltage Range |
20-132VAC |
| External Power, Voltage |
85-132VAC, 47-63 Hz |
| External Power, Current |
150 mA @ 132VAC |
| Mounting |
Vertical / Horizontal |
| Power Dissipation, maximum |
31.3 Watts |
| Thermal Dissipation, maximum |
106.73 BTU/Hr |
| On-state Voltage range |
79-132VAC, 47-63 Hz |
| Voltage |
120 Volts AC |
Industry Applications
The 1791-16AC excels in material handling, packaging lines, and process control systems where distributed I/O reduces wiring costs. For example, a conveyor system can use the 1791-16AC to collect limit switch and proximity sensor inputs while driving motor contactors and pilot lamps—all over a single Remote I/O link. Its 120VAC compatibility makes it a direct replacement in existing plants without changing field devices.
Installation Guide
Mount the 1791-16AC on a standard DIN rail or panel in either vertical or horizontal orientation. Vertical mounting improves airflow and allows higher output current ratings: 300 mA at 60°C and 600 mA at 30°C. Horizontal mounting reduces ratings to 150 mA at 60°C and 300 mA at 30°C. Verify that the external power supply delivers 85-132VAC at 47-63 Hz and that the total load current does not exceed the module’s capacity per group.
Maintenance & Reliability
Periodically inspect the 1791-16AC for dust accumulation, loose terminal connections, and signs of overheating. Because the module’s output current derates with temperature, ensure adequate ventilation around the unit. The module’s robust isolation (500VAC/1250VAC) protects against ground loops, reducing unexpected downtime. With proper care, this block I/O module delivers years of reliable service.
Compatibility & Integration
The 1791-16AC operates as a Remote I/O adapter, connecting to a main controller via a Remote I/O scanner. It supports daisy-chain topology, allowing multiple block I/Os to share the same communication cable. This module is compatible with a wide range of input devices—proximity switches, limit switches, selector switches, float switches, pushbuttons—and output devices such as pilot lamps, relay coils, horns, and solenoid actuators.
Buying Guide
Before ordering, confirm your system’s Remote I/O scanner compatibility and verify the required number of I/O points. Also check the continuous current draw of your connected devices to stay within the module’s output ratings. For genuine Allen-Bradley 1791-16AC modules with fast shipping and expert support, choose PLC Source PRO—your trusted source for industrial automation spares.