Allen-Bradley 1791-8AC Block I/O Module: Compact 120VAC Remote I/O Solution

Core Features & Applications

• The 1791-8AC provides a complete 16-point discrete I/O interface (8 in, 8 out) at 120VAC.
• It functions as a Remote I/O (RIO) adapter for Allen-Bradley's 3-wire RIO protocol.
• This module enables a daisy-chain topology using Belden 9463 cable for simplified wiring.
• Ideal for implementing cost-effective Distributed I/O architectures with PLC2, PLC3, PLC5, and SLC500 platforms.
• The built-in RIO interface ensures smooth data exchange with the central processor.

Technical Specifications

• Brand: Allen-Bradley
• Model: 1791-8AC
• Product Line: 1791 Block I/O
• Input Channels: 8 isolated channels.
• Input On-State Voltage: 79 to 132 VAC.
• Output Channels: 8 isolated channels.
• Output Voltage Range: 20 to 132 VAC.
• Output Current (Vertical Mount): 300-600 mA (30-60°C).
• External Supply: 85-132 VAC, 150 mA.
• Power Dissipation: Max 12.9 Watts.
• Isolation Voltage: 500 VAC (tested at 1250 VAC).
• Communication: Allen-Bradley RIO (Remote I/O) Protocol.
• Module Weight: Approx. 0.94 lbs (0.43 kg).

Performance & Environmental Data

• The module handles a surge current of 10A for 50ms recurring every 2 seconds.
• It features a low OFF-state leakage current of 3 mA maximum.
• Signal delay is typically 1 cycle (OFF to ON) and 8.3 ms (ON to OFF) at 60Hz.
• Operating temperature ranges from 30 to 60 degrees Celsius.
• It offers excellent noise immunity and group-to-group isolation for stable performance.
• Thermal dissipation is a maximum of 43.99 BTU/hour.

Installation & Integration Guide

• Mount the 1791-8AC module vertically or horizontally in a suitable enclosure.
• Connect the 85-132VAC external power to energize the module and its local logic.
• Wire your field devices (sensors, switches) to the eight 120VAC input terminals.
• Connect your output loads (contactors, lamps) to the eight 120VAC output terminals.
• Use Belden 9463 or approved equivalent cable to daisy-chain modules on the RIO network.
• Configure the RIO scanner (e.g., 1747-SN) in your controller to recognize the module's I/O data.

Packaging & Shipping

• Each unit ships in a secure individual box with protective packaging.
• Package Includes: One Allen-Bradley 1791-8AC Block I/O Module.
• We ship globally via reliable carriers: FedEx, UPS, and DHL.
• Tracking information is provided immediately after dispatch.

Frequently Asked Questions (FAQ)

• Q: Which controllers work with the 1791-8AC?
  A: It works with PLC2, PLC3, PLC5, and SLC500 processors using a 1747-SN scanner.
• Q: What cable is needed for the RIO network?
  A: You need Belden 9463 twinaxial cable or an approved equivalent.
• Q: Can I mix this module with other I/O on the same RIO chain?
  A: Yes, the RIO protocol supports mixing different compatible adapters on one daisy chain.
• Q: What is the maximum output current per point?
  A: It's 600 mA per point when mounted vertically at 30°C, derating to 300 mA at 60°C.
• Q: Does the module need a separate power supply?
  A: Yes, it requires an 85-132VAC external supply for module and logic power.

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