Product Overview
The Allen-Bradley 1791-24A8 is a block I/O module from the 1791 series, designed for reliable discrete I/O in remote I/O architectures. This self-contained unit integrates a power supply, PLC interface, I/O connections, and signal processing circuitry.
Technical Specifications Breakdown
Key parameters for the 1791-24A8 are listed below for quick reference:
| Feature | Specification |
|---|---|
| Product Type | Block I/O |
| Number of Inputs | Twenty-Four (24) |
| Input On-state Voltage Range | 79-132VAC |
| Number of Outputs | Eight (8) |
| Output Voltage Range | 20-123VAC |
| External Power Voltage | 85-132VAC |
| External Power Current | 150 mA |
| Power Dissipation (max) | 18.76 Watts |
| Thermal Dissipation (max) | 63.97 BTU/Hr |
| Weight | 1.88 lbs (0.85 kg) |
Industry Applications
Its 24 inputs and 8 outputs suit medium-density control points. From a maintenance perspective, the compact design allows quick replacement without disturbing adjacent wiring, minimizing downtime.
Installation & Setup Guidance
Mount the 1791-24A8 vertically or horizontally in a clean, dry enclosure. Connect external power (85-132VAC, 150 mA) to the designated terminals. For remote I/O communication, use Belden 9463 cable (blue, clear, shield). Configure baud rates (57.6K, 115.2K, or 230.4K) per network distance: up to 10,000 feet at 57.6K, 5,000 feet at 115.2K, or 2,500 feet at 230.4K. In daisy-chain topology, install an 82-ohm or 150-ohm terminating resistor at the last node to prevent intermittent communication.
Maintenance & Reliability
Inspect the module periodically for dust accumulation and loose connections. Ensure ambient temperature stays within safe limits to avoid thermal stress. The module dissipates up to 18.76 Watts; adequate ventilation is recommended. No internal adjustments are required.
Compatibility & Integration
The 1791-24A8 integrates with PLC-2, PLC-3, and PLC-5 controllers via its embedded remote I/O interface configured as a scanner. It also works with SLC 500 controllers using the 1747-SN remote I/O scanner. This flexibility simplifies upgrades in legacy systems.
Selection Guide & Purchasing Advice
When selecting this module, verify your controller compatibility and network topology. The 1791-24A8 is available from AutoDCSTech, a trusted supplier of industrial automation parts. Contact us to confirm current lifecycle status and availability before ordering.
Availability & Condition at AutoDCSTech
| Part Number | 1791-24A8 |
|---|---|
| Availability | In Stock |
| Condition | New |
| Warranty | One Year |
| Origin | US |
