1791-24BR Allen-Bradley 24 Input 8 Relay Output DC Block I/O

1791-24BR Allen‑Bradley 24‑Input 8‑Relay Output DC Block I/O

Key Technical Specifications

• Manufacturer: Allen‑Bradley.
• Model: 1791-24BR – 24‑point DC input / 8‑point relay output Block I/O.
• Input voltage range: 10‑30V DC (on‑state), with 11 mA max at 30V. Off‑state below 5V DC provides high noise immunity.
• Input current: minimum 2.5 mA at 10V DC guarantees reliable turn‑on; maximum 11 mA at 30V DC.
• Output relays: 8 form A (normally open) contacts. They switch 20‑132V AC at 1 A resistive – ideal for mixed voltage panels.
• External power requirement: 19.2‑30V DC at 300 mA to supply the module logic and inputs.
• Isolation ratings: 500V AC between power supply, remote I/O, I/O groups, and logic – prevents ground loops.
• Power dissipation: 14.5 W max (49.4 BTU/h) – ensure adequate ventilation in the enclosure.
• Environmental range: operate 0 °C to 60 °C, store ‑40 °C to 85 °C, 5‑95 % humidity non‑condensing.
• Dimensions & weight: 176.5 x 110.5 x 98 mm (6.95 x 4.35 x 3.85 in), 2.38 lb (1.08 kg).

Installation and Wiring Guidelines

• Mount the 1791-24BR vertically on a DIN rail as recommended – this optimises heat dissipation and derating.
• Wire the 24 DC inputs in three groups of eight; each group shares a common terminal for efficient field wiring.
• Connect an external 19.2‑30V DC power supply to the dedicated terminals – the module draws 300 mA max.
• Relay outputs are volt‑free contacts: you can connect AC or DC loads up to 132V AC / 1 A resistive.
• Use copper conductors rated 75 °C; tighten terminals to 0.8 Nm (7 lb‑in).

Compatible Controllers and Diagnostics

• The 1791-24BR works with PLC‑2, PLC‑3, PLC‑5/250, PLC‑5 family, and SLC 5/02 modular controllers.
• Built‑in status LEDs show communication health and I/O states – simplifies troubleshooting.
• Two switch assemblies let you configure rack number, baud rate, starting I/O group, and last state behaviour.
• Terminal strips on both sides provide easy access to remote I/O link, I/O wiring, and power connections.

Package Contents

• One Allen‑Bradley 1791-24BR Block I/O module with factory‑attached terminal blocks.
• Quick reference guide for wiring and switch settings.
• Mounting instructions and compliance information.
• All items ship in anti‑static protective packaging.

Frequently Asked Questions (FAQ)

• Can the 1791-24BR outputs switch DC voltage? Yes, the relay contacts are potential‑free. For DC loads the voltage must stay within the contact rating (30V DC / 1 A max).
• What is the minimum input current for a reliable ON state? At 10V DC the input draws at least 2.5 mA, which ensures a solid logic transition.
• Does the module include the power supply? No, you need an external 19.2‑30V DC supply (300 mA minimum) to power the module electronics.
• How do I set the I/O rack number on the 1791-24BR? Use the two rotary switch assemblies located on the front panel – they adjust rack number, baud rate, and last chassis settings.
• What is the isolation between input groups? 500V AC between groups and logic – this protects against voltage surges in different sections of the machine.

For inquiries or to place an order, contact us at sales@nex-auto.com or +86 153 9242 9628 (WhatsApp).
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