Configured for discrete AC load control in ControlLogix chassis architectures, the Allen-Bradley 1756-OA8 (1756-OA8 Digital AC Output Module) provides direct physical/electrical execution.

Catalog Designation & Module Classification

The 1756-OA8 module provides eight individual solid-state AC outputs divided into two isolated groups of four points each. The device interfaces field-side actuators, solenoids, and motor starters directly to the ControlLogix system backplane across a high-speed parallel interface.

Electrical & Physical Specifications

System Integration & Deterministic Backplane Performance

The module interfaces directly with the ControlLogix backplane bus, utilizing producer/consumer technology for deterministic network data transmission over EtherNet/IP platforms. Output state timing synchronization and system firmware compatibility are managed natively within Studio 5000 Logix Designer. Built-in electronic keying prevents module damage caused by installation into incorrect slot configurations.

Order Fulfillment Information

• 1 x 1756-OA8 AC Output Module
• 1 x Factory Sealed Box
• Note: Removable Terminal Block (RTB) units (catalog numbers 1756-TBCH or 1756-TBNH) must be ordered separately.

Installation & Wiring Framework

• Insert the module into any available slot within a 1756 ControlLogix chassis until the top and bottom latches secure completely.
• Verify field wiring isolation and turn off all input power sources before installing or removing the Removable Terminal Block (RTB).
• Route field wiring through the bottom of the RTB, utilizing individual strain reliefs to avoid tension on terminal connections.
• Maintain strict separation between high-voltage AC output conductors and low-voltage DC or communication bus lines within the panel wireways.

Frequently Asked Questions

• What is the maximum continuous current rating per output point for the 1756-OA8 module?

  Each individual channel handles up to 0.5 A continuous current at an ambient temperature of 60 deg C, subject to a total group limit of 2.0 A.

• Is the 1756-OA8 module capable of hot-swapping under live chassis power?

  Yes, the module supports Removal and Insertion Under Power (RIUP), allowing field swap-outs without interrupting system backplane communications.

• Does the 1756-OA8 package include the terminal block required for field wiring?

  No, the Removable Terminal Block (1756-TBCH or 1756-TBNH) is not included with the standard module package and must be specified separately.

• What amount of current does the module draw from the 5 VDC and 24 VDC backplane rails?

  The unit draws 200 mA from the 5 VDC backplane bus rail and 2 mA from the 24 VDC backplane bus rail during normal operation.

• What is the continuous isolation rating between output point groups?

  The module features a tested 50 V continuous isolation rating between output groups as well as between output channels and the chassis backplane.

• Does the 1756-OA8 output module support DC load switching applications?

  No, the output circuit topology utilizes solid-state AC switches designed strictly for operation within an alternating current range of 74 to 265 VAC.

• What happens to output states if backplane communication with the controller is lost?

  Each channel can be programmed via Studio 5000 to hold its last state, turn off, or turn on in response to a communication fault event.

• What size wire gauge can be connected to the compatible 1756 RTB units?

  The standard terminal blocks accept solid or stranded copper wire sizes ranging from 22 AWG to 14 AWG rated for appropriate system temperatures.