Allen-Bradley 1771-OMD/B 1771 PLC-5 I/O System Digital AC Output Module

The Allen-Bradley 1771-OMD/B serves as the primary 1771-OMD Digital AC Output Module utilized to execute isolated AC switching functions across 1771 PLC-5 I/O System platforms.

Hardware Specifications

Profinet / EtherNet/IP Deterministic Networks and I/O Density Scaling

The 1771-OMD/B routes 16 independent output channels within a single slot footprint, optimizing I/O density scaling inside legacy 1771 chassis topologies. When interfacing with supervisory hardware across Profinet or EtherNet/IP deterministic networks, the backplane bus communication velocity remains stable due to the 700 mA current profile of the module. Conformal coating updates included in the Series B architecture preserve structural trace integrity, ensuring continuous firmware flash compatibility and predictable logic processing when high inductive loads are switched concurrently.

Frequently Asked Questions

Q: What is the maximum cumulative current limitation for the entire 1771-OMD/B module?

A: While individual channels can support a maximum continuous load of 2 A, the cumulative electrical current across all 16 channels must not exceed 8 A per module.

Q: Does the 1771-OMD/B module include internal short-circuit fuse protection for each channel?

A: No. The module does not contain internal per-channel fusing. External fusing is required for each channel path to safeguard the output triacs from overcurrent failures.

Q: Can the 1771-OMD/B be removed from the chassis while the backplane is energized?

A: No. Online removal or insertion under power is not supported by the 1771 chassis backplane architecture and can induce electrical damage or trigger processor faults.

Field Installation Guidelines

• Wiring Arm Connection: Secure all field terminations to the 1771-WH wiring arm prior to latching the arm onto the module chassis pivot point.
• Conductor Separation: Route AC output load lines through separate physical wire pathways from low-voltage DC analog signaling or communication cables to avoid inductive interference.
• Inductive Load Suppression: Install external RC surge suppressors across connected AC inductive loads (such as solenoids or motor starter coils) to minimize voltage spikes during turn-off cycles.
• Chassis Slot Grounding: Ensure the universal 1771 I/O chassis grounding strip is connected to an absolute low-impedance earth ground to verify 1500 VAC channel isolation performance.