Description

The Allen-Bradley 1756-OX8I is an 8-channel isolated relay output module designed for the ControlLogix platform. This digital output module provides individual channel isolation, allowing for flexible control of diverse field devices operating at different voltage levels. It is engineered to handle both AC and DC loads, making it suitable for a wide range of industrial switching applications where galvanic isolation between channels or between the field and the backplane is required.

Features

• 8 individually isolated relay output channels
• Supports a wide operating voltage range: 5 to 125V DC and 10 to 240V AC
• Configurable as Normally Open (NO) or Normally Closed (NC) contact arrangements
• Designed for standard ControlLogix chassis mounting
• Low power consumption with a total backplane power requirement of 2.9 W
• Reliable pilot duty ratings of C300/R150

Applications

This module is typically deployed in industrial automation systems for interfacing the ControlLogix controller with field-level actuators, motor starters, solenoids, and alarm circuits. Its isolated design is particularly useful in environments requiring protection against electrical noise or where multiple voltage domains must be managed within a single I/O rack.

Technical Specifications

Installation Guidelines

• Ensure the ControlLogix chassis is powered down before inserting or removing the module to prevent electrical arcing or damage to backplane pins.
• The module is designed for chassis mounting; ensure it is fully seated and the locking latch is engaged.
• Use appropriate shielded cabling for field wiring to minimize EMI interference, especially when switching inductive loads.
• Ensure that the field power supply is correctly fused according to the load requirements and local electrical codes.
• Maintain adequate ventilation around the chassis to ensure the module stays within its operating temperature range (max 60 degC).

FAQ

Is the 1756-OX8I module suitable for high-speed switching applications?

No, as a relay output module, it is subject to mechanical bounce times (mean 1.2 ms) and is intended for general-purpose switching rather than high-speed pulse-width modulation or rapid cycling.

Does this module require external power for the relay contacts?

Yes, the relay contacts are isolated and require an external power source appropriate for the load being switched, within the specified voltage ranges of 5-125V DC or 10-240V AC.