Product Overview
When your control system demands a robust and flexible housing for ControlLogix modules, the Allen-Bradley 1756-A4 4-Slot ControlLogix Chassis delivers the structural foundation you need. This chassis provides the physical connections between modules and the ControlLogix backplane, ensuring reliable power distribution and high-speed data transfer across your automation network.
Part of the ControlLogix series, the Allen-Bradley 1756-A4 is designed for horizontal-only, back-panel mounting. It accepts a wide range of ControlLogix processors, I/O modules, communication adapters, and specialty modules, making it a versatile choice for both central and distributed control architectures.
Technical Specifications
The Allen-Bradley 1756-A4 offers the following key specifications:
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Number of Slots: 4
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Backplane Current (1.2V DC): 1.5 A (chassis/slot max)
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Backplane Current (3.3V DC): 4 A (chassis/slot max)
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Backplane Current (5.1V DC): 15 A (chassis), 6 A (slot max)
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Backplane Current (24V DC): 2.8 A (chassis/slot max)
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Power Dissipation: 6.1 BTU/hr (max 4 W)
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Power Consumption: 1.8 W
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Dimensions (WxHxD): 263 x 169 x 145 mm (10.35 x 6.65 x 5.71 in.)
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Cabinet Size (min): 507 x 507 x 203 mm (20 x 20 x 8 in.)
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Weight: 0.75 kg (1.7 lb)
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Mounting: Horizontal
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Enclosure: Open
Key Features & Benefits
The Allen-Bradley 1756-A4 chassis provides a high-speed communication path between modules and distributes power efficiently. Its backplane current ratings ensure stable operation even with high-power modules installed.
Equipped with Removal and Insertion Under Power (RIUP) capability, the 1756-A4 allows you to replace modules without shutting down the system, minimizing downtime. Electronic keying prevents incorrect module installation, reducing costly errors.
The chassis supports distributed applications, enabling I/O modules to be located remotely from the processor. This eliminates long signal cable runs and simplifies system layout.
Industry Applications
The Allen-Bradley 1756-A4 is ideal for a wide range of industries, including:
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Manufacturing: Automate assembly lines, material handling, and packaging systems.
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Process Control: Manage chemical, oil & gas, and pharmaceutical processes with reliable I/O handling.
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Infrastructure: Control water treatment, power generation, and building automation systems.
In a typical manufacturing line, the 1756-A4 houses a ControlLogix processor and I/O modules, coordinating machine sequences and ensuring precise timing. In distributed applications, it can be placed near remote sensors and actuators, reducing wiring costs and improving signal integrity.
Installation & Setup Guidance
Mount the Allen-Bradley 1756-A4 horizontally on a back panel using the provided mounting holes. Ensure the cabinet meets the minimum size requirement of 507 x 507 x 203 mm to allow proper airflow and access.
Install a compatible power supply from the supported list: 1756-PA72, 1756-PB72, 1756-PA75, 1756-PB75, 1756-PC75, or 1756-PH75. The power supply mounts externally to the chassis via the provided interface.
Fill any empty slots with slot filler modules (1756-N2) to maintain proper cooling and protect the backplane. Insert modules firmly until they latch, and verify proper seating before applying power.
Maintenance & Reliability
Regularly inspect the chassis for dust accumulation and ensure the backplane contacts are clean. Check that all modules are securely seated and that the power supply connections remain tight.
The open enclosure design allows for natural cooling, but ensure the cabinet has adequate ventilation. Avoid exposing the chassis to excessive vibration or corrosive environments.
With proper maintenance, the 1756-A4 delivers long service life, reducing total cost of ownership and preventing unplanned downtime.
Compatibility & Integration
The Allen-Bradley 1756-A4 is fully compatible with the ControlLogix platform, supporting all ControlLogix processors, I/O modules, communication adapters, and specialty modules. It also accepts Encompass partner and third-party modules that meet ControlLogix specifications.
Each chassis requires its own system power supply, and the 1756-A4 works seamlessly with the listed power supplies. For distributed I/O setups, install a communication adapter in the chassis to link remote I/O to the main processor.
Selection Guide & Purchasing Advice
Before purchasing the Allen-Bradley 1756-A4, verify your slot count requirements and power budget. Check that your chosen power supply is on the compatible list and that your cabinet space meets the minimum dimensions.
Consider future expansion needs—if you anticipate adding more modules, you might opt for a larger chassis like the 1756-A7 or 1756-A10. However, the 1756-A4 remains a cost-effective choice for smaller control panels.
For genuine, reliable parts, PLC Source PRO offers the Allen-Bradley 1756-A4 with fast shipping and competitive pricing. Ensure you purchase from a trusted supplier to guarantee authentic components and avoid counterfeit risks.