Product Introduction
The Allen-Bradley 1756-OB16I is a ControlLogix Isoloated DC Output Module designed for demanding industrial automation applications. This module provides sixteen individually isolated outputs, each capable of sourcing or sinking 12/24 VDC loads. With individually isolated channels, the 1756-OB16I allows each output to operate from a separate voltage source, offering maximum wiring flexibility. It is part of the Rockwell Automation ControlLogix platform, ensuring seamless integration into existing control systems.
Key Technical Specifications
| Specification |
Value |
| Outputs |
16-Point Individually Isolated |
| Operating Voltage Range |
10-30 VDC |
| Current per Point |
2 A @ 30 °C, 1 A @ 60 °C (linear derating) |
| Current per Module |
8 A @ 30 °C, 4 A @ 60 °C (linear derating) |
| Power Dissipation (Max) |
3.6 W @ 60 °C |
| Backplane Current @ 5V |
350 mA |
| Backplane Current @ 24V |
3 mA |
| Output Delay OFF to ON |
1 ms max |
| Output Delay ON to OFF |
2 ms max |
| Removable Terminal Block |
1756-TBCH or 1756-TBS6H (36 pin) |
These specifications make the Allen-Bradley 1756-OB16I a robust choice for controlling discrete loads such as relays, solenoids, and indicators. The linear derating ensures reliable operation across the temperature range.
Industry Applications
The Allen-Bradley 1756-OB16I excels in applications requiring high channel‑to‑channel isolation. Common use cases include:
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Manufacturing Assembly Lines: Control multiple solenoid valves or actuators from a single module, with each channel operating at different voltage potentials.
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Packaging Machinery: Drive indicator lamps and alarms with precise timing, leveraging the fast 1 ms turn‑on delay.
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Process Control: Interface with field devices that require galvanic isolation to prevent ground loops.
For existing ControlLogix systems, upgrading to the 1756-OB16I provides enhanced diagnostic capabilities and configurable safe states, reducing unplanned downtime.
Installation & Setup Guidance
Install the Allen-Bradley 1756-OB16I directly into any 1756 local or remote chassis. The module occupies a single slot. Use either the 1756-TBCH or 1756-TBS6H removable terminal block (RTB) for wiring. Ensure wiring follows the sinking or sourcing configuration per your load requirements.
For optimum performance, use external fusing: a 5x20mm 4 A quick‑acting fuse (SOC p/n MQ2-4A) is recommended to protect each output. The module supports multiple communication formats including rack optimization and scheduled output data; configure these in your ControlLogix programming environment.
Maintenance & Reliability
The 1756-OB16I module features rugged construction with no internal fuses, but external protection is advised for long‑term reliability. Routine maintenance includes checking terminal connections for tightness and verifying that ambient temperature remains between 0 °C and 60 °C. The module’s power dissipation of 3.6 W maximum ensures low heat generation, contributing to extended service life. The individually isolated outputs also simplify troubleshooting since a fault on one channel does not affect others.
Compatibility & Integration
The Allen-Bradley 1756-OB16I integrates fully with ControlLogix processors and remote racks. It supports output data formats such as listen‑only and scheduled output, making it compatible with both standard and safety‑critical applications. The module works with all 1756 I/O chassis and is designed for use with RSLogix 5000 software. For existing systems, the 1756-OB16I can replace older discrete output modules, offering better isolation and easier wiring.
Selection Guide & Purchasing Advice
When ordering the Allen-Bradley 1756-OB16I, verify that your chassis has a free slot and that your power supply can handle the backplane current: 350 mA at 5V and 3 mA at 24V. Available at UBEST Automation (site ubest101), this module comes with genuine Rockwell Automation quality. Ensure you have the correct removable terminal block (1756-TBCH or 1756-TBS6H) for your wiring needs. For large projects, consider stocking multiple units to minimize downtime.