Allen-Bradley 1756-OB16I Output Module

The Allen-Bradley 1756-OB16I, also cataloged as the 1756-OB16I Digital Output Module, operates as a dedicated hardware component for high-density discrete actuation within ControlLogix backplane platforms. The hardware establishes electronic switching across 12-24 VDC (10-30 VDC operating range) control loops at up to 2 A per point. Each of the 16 output channels features individual galvanic isolation up to 250 V continuous, preventing electrical noise transfer and ground loops across independent power source circuits.

Hardware Specifications

ControlLogix System Architecture & Backplane Protocol Features

The module communicates over the local ControlLogix backplane bus utilizing high-velocity CIP (Common Industrial Protocol) framing. Backplane bus communication velocity guarantees low deterministic latency during field output state updating. High-density I/O routing protocols ensure synchronous cyclic data transmission to the system controller, matching configured Requested Packet Interval (RPI) rates down to sub-millisecond thresholds. Firmware flash compatibility enables online updates through Studio 5000 Logix Designer without physically dismounting the chassis assembly.

Frequently Asked Questions

Q: Can the 1756-OB16I module be removed or inserted under power (RIUP)?

A: Yes, the module supports Removal and Insertion Under Power (RIUP) within a powered ControlLogix chassis. However, field power connected to the 36-pin Removable Terminal Block (RTB) must be isolated prior to wiring block disconnection to prevent hazardous arc flash or unintended output state toggling.

Q: Does the 1756-OB16I support both sourcing and sinking field wiring configurations?

A: Yes, each isolated channel can be individually wired in either a sinking or sourcing topology, provided field voltage remains strictly within the 10-30 VDC operating window and individual channel isolation parameters are respected.

Field Installation Guidelines

• Verify backplane chassis grounding complies with IEEE 1100 standards; ensure the grounding conductor connects directly to the enclosure single-point star ground using low-impedance copper wire.
• Secure the 36-pin Removable Terminal Block (RTB) retaining screws to maintain continuous mechanical locking against chassis vibration profiles.
• Route low-voltage DC output wiring in separate wiring channels away from high-voltage AC cables and variable frequency drive output leads to mitigate inductive noise coupling.
• Install external inductive surge suppression devices (such as flyback diodes) across connected DC inductive loads to protect output switching transistors from high-voltage transients.