The Allen-Bradley 1756-OF8H, also cataloged as the 1756-OF8H Analog Output Module, operates as a dedicated hardware component for converting controller data into analog current and voltage output signals within ControlLogix automation platforms.

Model Reference and Configuration

The Allen-Bradley 1756-OF8H is an 8-channel analog output module designed for ControlLogix chassis systems. The module provides differential analog output channels with HART protocol capability for current and voltage signal transmission.

The output channels receive processed values from the Logix controller and convert digital controller commands into field-level analog signals. Configuration requires compatible controller firmware, Logix software settings, and chassis installation.

Hardware Specifications

ControlLogix Analog Output Characteristics

The 1756-OF8H interfaces with ControlLogix processor modules through the chassis backplane and provides eight analog output channels for external devices. The module converts controller output values into configured current or voltage signals.

The HART protocol capability allows compatible field devices to exchange additional digital information through supported analog current loops. Output configuration parameters are managed through the Logix controller environment.

Deterministic Backplane Data Processing

Allen-Bradley ControlLogix systems use deterministic backplane communication for module data exchange. The 1756-OF8H receives output commands from the processor and updates field output channels according to configured module parameters.

Firmware flash compatibility, electronic keying settings, and controller revision matching must be verified during system integration. The module operation depends on correct communication between the processor and I/O subsystem.

Signal Isolation and Output Protection

The module provides 50 V continuous isolation between the output circuitry and internal electronics. The output channels include 24 VDC overvoltage protection to reduce the risk of damage from field wiring conditions.

Proper shield termination, grounding practices, and cable separation are required when installing analog output wiring near high-voltage or high-frequency equipment.

Ordering Information

• 1 x Allen-Bradley 1756-OF8H ControlLogix Analog Output Module
• 1 x ControlLogix compatible module assembly
• 1 x Product identification label
• ControlLogix chassis, power supply, field wiring, and external HART devices are not included unless separately specified

Installation Guidelines

Module Mounting

• Install the module into a compatible ControlLogix chassis slot.
• Verify chassis power capacity before adding the module.
• Confirm module seating and locking mechanism engagement.

Field Wiring

• Use appropriate shielded cable for analog output connections.
• Separate analog signal wiring from power conductors and switching circuits.
• Confirm current or voltage output configuration before commissioning.
• Verify HART device compatibility when using HART communication functions.
• Check output values through controller diagnostics after startup.

Frequently Asked Questions

• What type of signals does the 1756-OF8H provide?

  The module provides analog current and voltage output signals through eight differential output channels.

• How many output channels are available?

  The 1756-OF8H provides 8 differential analog output channels for ControlLogix applications.

• Does the module support HART communication?

  Yes. The module supports HART protocol operation with compatible field devices.

• What current ranges are supported?

  The module supports 0-20 mA and 4-20 mA analog current output ranges.

• What is the module resolution?

  The analog output resolution is 15-16 bits depending on configured output operation.

• What is the isolation voltage rating?

  The module provides 50 V continuous isolation for the output circuitry.

• What is the overvoltage protection rating?

  The output channels include 24 VDC overvoltage protection.

• What configuration is required before operation?

  The module requires Logix controller configuration, output channel setup, and compatible firmware settings before use.