Allen-Bradley 1756-OB16IS ControlLogix 16-Point Isolated Digital Output Module

Individual Channel Isolation and High-Performance Switching

The Allen-Bradley 1756-OB16IS serves as a specialized digital output solution within the ControlLogix platform, specifically engineered for applications requiring high electrical independence between circuits. This module manages 16 output points, each featuring complete galvanic isolation to prevent crosstalk and protect the system backplane from field-side electrical noise. By supporting both sinking and sourcing configurations, the module provides engineers with maximum flexibility when interfacing with diverse DC loads. Furthermore, the 1756-OB16IS executes high-speed switching with a typical turn-on time of 1ms, ensuring rapid response for time-critical automation sequences.

Scheduled Output Functionality and System Synchronization

Beyond standard digital switching, the 1756-OB16IS incorporates advanced scheduling capabilities for 8 of its 16 points. These scheduled outputs synchronize precisely with the Coordinated System Time (CST) of the ControlLogix backplane, allowing the controller to trigger events at microsecond-level accuracy. This feature proves essential in high-speed motion or packaging applications where hardware latency must remain deterministic. Additionally, the module allows users to define specific fault states—Hold Last State, On, or Off—ensuring that the industrial process reaches a safe condition during a communication loss or controller failure.

Robust Electrical Protection and Environmental Resilience

To withstand demanding industrial environments, the 1756-OB16IS features a rugged design capable of handling significant surge currents up to 4A for 10ms. This capability allows the module to drive inductive loads without premature component wear. While maintaining a steady 2A contact rating per point, the unit also provides 250V continuous isolation between individual outputs and the backplane. Moreover, the hardware sustains reliable operation in temperatures up to 60°C and resists mechanical stress up to 30G of shock. These certifications verify the module’s suitability for heavy-duty applications in the automotive, energy, and manufacturing sectors.

Key Technical Specifications

• Manufacturer: Allen-Bradley / Rockwell Automation
• Model Number: 1756-OB16IS
• Product Line: ControlLogix
• Module Type: Isolated Digital Output
• Number of Outputs: 16 (Individually Isolated)
• Voltage Category: 12/24V DC
• Operating Voltage Range: 10V to 30V DC
• Continuous Current Rating: 2A per point (8A maximum per module at 30°C)
• Scheduled Outputs: 8 points
• Backplane Current: 350mA at 5.1V DC / 2.5mA at 24V DC
• Isolation Voltage: 250V (Continuous)
• Signal Delay (Max): 1ms (Off to On) / 2ms (On to Off)
• Dimensions: 3.5cm x 14.2cm x 14.5cm
• Origin: USA

Typical Industrial Applications

• Driving solenoid valves and actuators with independent power sources.
• Interfacing with high-speed sorting and labeling equipment.
• Managing safety-critical signaling in power distribution centers.
• Controlling DC motor starters in harsh electromagnetic environments.