Allen-Bradley 1771-OAN PLC 5 Digital AC Output Module

The Allen-Bradley 1771-OAN, also cataloged as the 1771-OAN Digital AC Output Module, operates as a dedicated hardware component for binary AC load switching within PLC 5 platforms. The assembly converts logic commands received across the chassis backplane into physical state changes for 32 independent AC outputs, utilizing triac switching circuits arranged in four isolated groups of eight channels.

Hardware Specifications

Backplane Bus Communication Velocity and High-Density Scaling

The electronic architecture interfaces with the 1771 chassis infrastructure to execute high-density scaling of discrete AC points across a single slot. Data transfer occurs via BCD or Natural Binary data formats, syncing directly with the main processor scan to maintain backplane bus communication velocity parameters. The control logic relies on native firmware flash compatibility paths across the PLC-5 processor family, allowing the 800 mA backplane current load to remain constant without fluctuating during multi-channel execution.

Frequently Asked Questions

Q: How does the maximum continuous current rating adjust to ambient temperature increases within the local electrical enclosure?

A: The module operates under a strict thermal derating curve. At 30 deg C, each independent point allows up to 1.0 A continuous load, which decreases to 0.3 A per point when the ambient environment reaches 60 deg C to protect the triac junctions from thermal runaway.

Q: Can this module be extracted from the 1771 rack infrastructure while the backplane bus is actively powered?

A: No. The 1771 I/O architecture does not support live removal or insertion under power. Removing the component during active backplane communication can generate electrical noise, disrupt processor execution, and cause terminal damage to the backplane connectors.

Field Installation Guidelines

• Chassis Keying and Insertion: Prior to module insertion, install plastic keying bands on the chassis backplane connector between pins 6 and 8. Align the module housing with the top and bottom chassis rails, sliding it forward until the locking latch engages the frame completely.
• Wiring Arm Attachment: Secure the 1771-WH wiring arm to the pivot bar of the chassis slot. Terminate all 85-264 VAC field wiring onto the screw terminals before clipping the arm onto the front face of the module to prevent physical strain on the PCB.
• Group Isolation and Wiring: Maintain separation between the four independent electrical groups when routing external AC supply lines. Wire each group to its respective fused power branch to ensure proper circuit isolation and prevent cross-phase short circuits.
• Conductor Routing: Keep all AC output load wires isolated from low-voltage DC or analog signal cables within the wire trunking to prevent high-frequency inductive coupling from shifting into nearby instrumentation lines.