Allen-Bradley 1746-OB32/D SLC 500 Digital Output Module

The Allen-Bradley 1746-OB32/D, also cataloged as the 1746-OB32/D digital output module, serves as a discrete output execution unit for 24 VDC sourcing signal switching within SLC 500 backplane-based control architectures. The Allen-Bradley 1746-OB32/D (1746-OB32/D digital output module) provides direct electrical actuation of field loads across 32 independent output points under SLC 500 chassis communication.

The module interfaces with the SLC 500 backplane to execute digital state transitions driven by controller scan cycles. Output switching is implemented through solid-state sourcing channels designed for mixed inductive, capacitive, and resistive load environments.

Hardware Specifications

SLC 500 Backplane I/O Density Scaling and Output Switching Behavior

The 1746-OB32/D implements high-density discrete output mapping across a 32-channel architecture, with each channel addressed through backplane scan synchronization. I/O density scaling is achieved by consolidating multiple output points into a compact module footprint while maintaining independent channel switching boundaries.

Backplane communication is executed via deterministic scan cycles inherent to the SLC 500 chassis, where output state updates are latched at the end of each processor scan. The module supports mixed load switching, with internal channel grouping designed to distribute thermal and electrical stress across the output array.

Frequently Asked Questions (FAQ)

Q: Can the 1746-OB32/D outputs be hot-swapped during system operation?
A: No hot-swap operation is supported. Module removal requires chassis power-down to avoid backplane disturbance.

Q: Does each output channel operate independently under the backplane scan?
A: Yes. Each of the 32 channels is individually addressed and updated per SLC 500 scan cycle.

Q: What is the limiting factor for simultaneous output loading?
A: The constraint is defined by aggregate current capacity across the module and per-channel thermal dissipation limits within the 5 A @ 24 VDC specification.

Field Installation Guidelines

Install the 1746-OB32/D into a compatible SLC 500 chassis slot with correct backplane alignment. Ensure chassis power is removed prior to insertion or removal to prevent bus disturbance.

Field wiring shall be terminated according to terminal assignment drawings, with attention to correct polarity for 24 VDC sourcing outputs. Cable routing must separate output conductors from high-frequency switching or high-voltage AC lines to minimize induced coupling.

Verify grounding continuity of the control cabinet before energization. All output loads should be individually fused where inductive switching transients are expected.