Allen-Bradley 1791-24BR Block I/O Module Mixed Input Output

Product Overview

The Allen-Bradley 1791-24BR is a block I/O module from the Rockwell Automation 1791 Block I/O series. This mixed input and output module combines 24 DC inputs and 8 DC relay outputs, all operating at 10 to 30 Volts DC. Designed for decentralized control, it reduces wiring and cabinet space in manufacturing environments. The 1791-24BR is well-suited for applications requiring both discrete sensing and relay switching in a single compact unit.

Technical Specifications Breakdown

Key parameters for the 1791-24BR are listed below for quick reference:

Industry Applications

For example, in a packaging machine, the 24 DC inputs can monitor sensor positions while the 8 relay outputs control actuators or alarms. In material handling systems, the 1791-24BR reduces cabling by placing I/O near the process. Its relay outputs handle AC loads up to 132V AC, making it suitable for switching pilot lights, contactors, or small motors.

Installation & Setup Guidance

Mount the 1791-24BR vertically on a DIN rail for optimal airflow. Use the terminal strips on the left and right sides for remote I/O link, input/output connections, and power. Configure the two switch assemblies to set the I/O rack number, communication rate, starting I/O group, last state, and last chassis. Ensure external power is within 19.2-30V DC. The module is self-contained with its own signal conditioning and power supply, simplifying installation.

Maintenance & Reliability

Periodically inspect terminal connections for tightness and check status indicators for communication and I/O health. Operate within the specified voltage ranges to prevent damage. The module's non-condensing relative humidity range of 5-95% allows use in many industrial environments. No special maintenance is required beyond routine visual checks.

Compatibility & Integration

The 1791-24BR is compatible with PLC-2, PLC-3, PLC-5/250, PLC-5 family, and SLC 5/02 controllers. It communicates via remote I/O link, allowing integration into existing Allen-Bradley networks. The module's status indicators simplify troubleshooting of communication and I/O states.

Selection Guide & Purchasing Advice

When selecting a block I/O module, consider the number and type of I/O points needed. The 1791-24BR offers a balanced mix of 24 DC inputs and 8 relay outputs. Verify current lifecycle status and availability with AutoDCSTech before ordering. AutoDCSTech stocks this module and can advise on alternatives if needed.

Troubleshooting & Common Issues

If inputs do not respond, check the on-state voltage range (10-30V DC) and verify wiring. For output issues, confirm the load is within 20-132V AC at 1A resistive max. Use status indicators to isolate communication faults. Ensure external power is stable within 19.2-30V DC. For persistent problems, consult the product manual.