The 1756-OB8EI is a high-integrity digital DC sourcing output module designed for the Allen-Bradley ControlLogix 1756 chassis platform. This module provides eight independent, galvanically isolated output channels, each equipped with integrated electronic fusing to protect against short-circuit conditions and overcurrent events. It is engineered for demanding industrial environments, including power distribution, automotive manufacturing, and water treatment, where reliable, low-latency control of field devices such as solenoids, relays, and valves is required.

Features

• Eight isolated DC sourcing output channels.
• Electronic fusing per channel for rapid short-circuit protection.
• Point-level diagnostics with +/- 1 ms timestamp accuracy.
• Supports 10 to 30 VDC operating voltage range.
• Compatible with 1756-TBCH and 1756-TBS6H Removable Terminal Blocks (RTB).
• Designed for single-slot installation in any ControlLogix chassis.

Applications

This module is suitable for critical control applications requiring channel-to-channel isolation to prevent common-tie interference. It is commonly used to drive external field loads such as pilot lamps, buzzers, and hydraulic valves while maintaining isolation between independent DC power loops.

Technical Specifications

Installation Guidelines

• Ensure the ControlLogix chassis is powered down before inserting or removing the module.
• Use a compatible 1756-TBCH or 1756-TBS6H Removable Terminal Block for field wiring.
• Maintain proper grounding practices for the chassis to ensure effective EMI protection.
• Ensure adequate ventilation within the enclosure; observe derating requirements for current based on ambient temperature.
• Handle with care to prevent electrostatic discharge (ESD) damage to the module backplane connectors.

FAQ

Q: Does the 1756-OB8EI require an external power supply?
A: Yes, the module requires an external 24 VDC power source to drive the field loads connected to the output channels.

Q: What is the purpose of the electronic fusing?
A: The electronic fusing provides rapid, resettable protection for each channel, tripping in under 500 microseconds during an active short-circuit to prevent damage to the module and field wiring.