1794-OB8 | Allen Bradley Flex I/O 8-Point 24V DC Digital Sourcing Output Module

Technical Overview

The 1794-OB8 (Part Number 1794-OB8) is a high-density discrete output component engineered for the Allen Bradley Flex I/O platform. This module provides eight independent sourcing outputs, serving as a critical interface for distributed control systems where modularity and reduced cabinet footprint are required. It facilitates direct communication with the Flexbus to drive various field-side loads such as actuators, indicators, and solenoids.

Designed for industrial resilience, the 1794-OB8 (1794-OB8) utilizes a sourcing configuration, meaning it supplies voltage from the DC common bus to the connected load when activated. The architecture includes opto-isolation to shield internal logic from field-side electrical interference and potential transients.

Detailed Specifications

• Module Type Digital DC Sourcing Output

• Output Quantity 8 Non-isolated Channels

• Operating Voltage Range 10V DC to 31.2V DC (24V DC Nominal)

• Output Current Rating 4.0A maximum per module (0.5A per channel)

• On-state Voltage Drop 0.5V DC maximum

• Off-state Leakage Current 0.5mA maximum

• Flexbus Current Consumption 60mA at 5V DC

• Maximum Power Dissipation 3.3W at 31.2V DC

• Thermal Dissipation 11.2 BTU/hr at 31.2V DC

• Isolation Voltage 50V Continuous (Basic Insulation Type)

• External Power Supply 24V DC Nominal (10V to 31.2V DC range)

• Mounting Configuration Horizontal or Vertical orientation on terminal base

Application Scenarios

The 1794-OB8 (Part Number 1794-OB8) is commonly implemented in decentralized automation architectures across several sectors

• Direct control of 24V DC pneumatic solenoid valves and manifold blocks.

• Operation of small DC relays and motor starters in remote panels.

• Activation of status pilot lights and visual alarm indicators.

• Distributed I/O for material handling systems to minimize long-run wiring.

Technical FAQ

Does this module include the terminal base for wiring?No, the 1794-OB8 (1794-OB8) is the plug-in electronic module only. It must be installed onto a compatible terminal base, such as the 1794-TB2, 1794-TB3, or 1794-TB3S, to facilitate field connections.

What is the functional difference between sourcing and sinking for this unit?As a sourcing module, the 1794-OB8 (Part Number 1794-OB8) sources current to the load. The external field device must be connected to the negative/common side of the power supply to complete the electrical circuit.

Is there integrated short-circuit protection for the outputs?The module is built for industrial durability but does not feature internal electronic short-circuit protection. It is recommended to install external fusing to protect individual channels from overcurrent or wiring faults.