Description

The product photos shown are not of the actual items. Please contact sales@fyplc.cn for details.

📌 Allen‑Bradley 1791‑24A8 – Block Remote I/O Module

The Allen‑Bradley 1791‑24A8 is a legacy Block I/O discrete input/output module used in Rockwell Automation Remote I/O (RIO) systems. It combines a significant number of field I/O channels with an integrated Remote I/O interface and is designed for decentralized I/O in distributed control and PLC applications.

📊 Technical Overview

Product Type: Block I/O remote I/O module (discrete)

Manufacturer: Allen‑Bradley (Rockwell Automation)

Input/Output Points:

24 discrete inputs (120 VAC)

8 discrete outputs (120 VAC)

Input Voltage Range: ~79–132 VAC (on‑state)

Output Voltage Range: ~20–132 VAC

External Power: 85–132 VAC @ ~150 mA

I/O Configuration:

3 groups of 8 inputs

1 group of 8 outputs

Communication: Integrated Remote I/O (RIO) interface for connection to PLC‑2, PLC‑3, PLC‑5, or SLC 500 (via 1747‑SN scanner).

Mounting: Vertical or horizontal installation.

Dimensions: ~6.95 × 4.35 × 3.85 in (177 × 110 × 98 mm)

Environmental: Typical industrial ambient operational range; withstands standard RIO humidity/temp levels.

🧠 Features & Functionality

All‑in‑One Remote I/O Block: Combines a built‑in Remote I/O communication interface, line power supply, and discrete I/O channels in one module for simplified field wiring.

Remote I/O Support: Works with Allen‑Bradley / Rockwell Automation PLC families capable of Remote I/O scanning, including early PLC‑2, PLC‑3, PLC‑5 and SLC 500 via an RIO scanner adapter (e.g., 1747‑SN).

Discrete I/O Monitoring & Control: 24 inputs allow sensing of field signals (e.g., switches, sensors), and 8 outputs drive actuators, lamps, solenoids, etc., directly on PLC logic commands.

Integrated Power System: Uses the same AC power source for module logic and I/O points.

⚙️ Applications

The 1791‑24A8 was typically used in:

✔ Distributed control systems where remote I/O reduces wiring complexity.
✔ Legacy PLC systems needing a mix of discrete inputs and outputs managed remotely.
✔ Factory automation panels and machine interface racks requiring 120 VAC discrete control points.

Because of its Remote I/O communication compatibility, it was ideal for decentralizing I/O modules close to machinery while centralizing PLC logic.

📌 Lifecycle Status

This module is discontinued/obsolete per Rockwell Automation’s official lifecycle notice (discontinued as of 2015).

Replacement or migration strategies generally involve moving to modern I/O platforms like POINT I/O, Flex I/O, or EtherNet/IP‑based distributed I/O for newer PLC families.

Summary: The 1791‑24A8 is a legacy Allen‑Bradley Block I/O module with 24 AC inputs and 8 AC outputs, integrated Remote I/O interface and onboard power. It was widely used for decentralized discrete I/O in older Allen‑Bradley PLC systems but is now obsolete