Product Overview

The Allen-Bradley 1756-A17 is a high-capacity, 17-slot chassis designed to serve as the backbone of large-scale ControlLogix automation systems. Built for industrial environments requiring maximum I/O density and processing power, this chassis enables seamless communication between modules by providing a high-speed backplane for data exchange and power distribution. It is a critical component for complex machine control, large-scale plant automation, and distributed control systems where reliability is paramount.

The 1756-A17 chassis incorporates sophisticated features that facilitate easy maintenance and system uptime. Its support for Removal and Insertion Under Power (RIUP) allows technicians to replace I/O or communication modules without halting the entire process, drastically reducing Mean Time to Repair (MTTR). Additionally, the chassis includes electronic keying to prevent the accidental installation of incorrect modules, safeguarding your investment and preventing potential hardware damage. Whether used in automotive assembly lines, municipal water treatment facilities, or large-scale logistics centers, the 1756-A17 offers the structural integrity and electrical stability required for enterprise-grade automation.

Technical Specifications

Model Configuration Explanation

The 1756-A17 model number provides a clear understanding of its physical and functional capabilities:

• 1756: Identifies the product as part of the ControlLogix family of industrial controllers.

• A: Denotes the chassis classification.

• 17: Specifies the number of available slots for I/O, communication, and controller modules.

Typical Applications

The 1756-A17 is favored by system integrators for applications requiring high modularity:

• Automotive Manufacturing: Supports complex vehicle assembly lines where multiple CPUs, motion controllers, and high-density I/O modules are required to be housed in one central location.

• Food & Beverage Processing: Integrates numerous communication gateways and motion control modules for packaging and palletizing operations.

• Water & Wastewater Treatment: Acts as the central hub in large control panels for remote monitoring of filtration, pumping, and sewage treatment telemetry.

• Logistics & Warehousing: Centralizes control for high-speed automated sorting systems, conveyor logic, and variable frequency drive (VFD) communication.

System Compatibility

The 1756-A17 is fully compatible with all standard 1756 ControlLogix modules, including:

• Processors: 1756-L7x, 1756-L8x series controllers.

• I/O Modules: Digital, analog, and specialty I/O cards.

• Communication Modules: EtherNet/IP (1756-ENxT), ControlNet, and DeviceNet bridges.

• Power Supplies: 1756-PB50, 1756-PA72, etc. (mounted to the left of the chassis).

  The chassis backplane provides the necessary power and high-speed bus connectivity to ensure that these diverse modules operate as a single, coherent control unit.

Installation & Mounting Guidelines

• Horizontal Orientation: The chassis must be mounted horizontally only to ensure that heat generated by the modules can dissipate through the natural ventilation channels.

• Clearance Requirements: To ensure adequate cooling, maintain the following minimum clearances:

• Top: 15.3 cm (6.0 in.)

• Bottom: 5.1 cm (2.0 in.)

• Left (Power Supply Side): 10.2 cm (4.0 in.) + supply width

• Right: 7.7 cm (3.0 in.) + supply width

• Mounting Tabs: The chassis includes 10 mounting tabs (5 top, 5 bottom) for secure attachment to the subpanel.

• Grounding Requirements: A Functional Earth (8.3 mm² / 8 AWG) and Protective Earth (2.1 mm² / 14 AWG) ground connection is mandatory to ensure safety and prevent signal noise interference.

• Hardware: If utilizing SEM screws, you will need 5 Phillips screws, 5 flat washers, 5 split-lock washers, and 5 SEM screws per installation.

Product Advantages

• High-Density Control: 17 slots provide the largest standard capacity for complex automation projects, reducing the need for multiple, interconnected chassis.

• RIUP Functionality: Enables maintenance and module hot-swapping under power, significantly increasing system availability.

• Electronic Keying: Eliminates human error by ensuring only the correctly programmed module can be inserted into a configured slot.

• Robust Diagnostics: When combined with intelligent I/O modules, the backplane communication supports comprehensive system diagnostics for faster fault identification.

Ordering Information

• 1756-A17 ControlLogix 17-Slot Chassis.

• Standard industrial packaging.

• Note: Confirm mounting hardware requirements based on your specific cabinet subpanel type. Ensure the total backplane current draw (10A @ 5V, 2.8A @ 24V) does not exceed the capacity of your chosen power supply.

Frequently Asked Questions

• Does the 1756-A17 come with a power supply?

  No, the chassis is a passive backplane unit. You must purchase a compatible ControlLogix power supply (e.g., 1756-PA72 or 1756-PB50) separately.

• Can I install this chassis vertically to save space?

  No. The chassis is strictly designed for horizontal mounting to facilitate proper thermal convection. Vertical mounting will lead to overheating and potential hardware failure.

• What does "electronic keying" do?

  It prevents an incorrectly typed module from being used in a slot configured for a different module, preventing data corruption and hardware damage during setup.

• Is the chassis compatible with legacy ControlLogix modules?

  Yes, the 1756 backplane architecture is backward compatible with most legacy ControlLogix modules, allowing for phased system upgrades.

• How do I protect the backplane from metal shavings?

  Use the debris strips provided on the chassis until all wiring and mounting are complete. Metal shavings can cause short circuits on the backplane.

• What grounding wire should I use?

  Per documentation, use an 8 AWG Functional Earth wire and a 14 AWG Protective Earth wire to ensure electromagnetic compatibility and safety.

• Can I use this for Sequence of Events (SOE) timestamping?

  Yes, the 1756-A17 supports high-speed communication backplane timing, allowing for SOE timestamping when used with compatible input modules.

• How much space does the chassis occupy in a cabinet?

  The chassis itself is 74.5 cm wide, but you must account for the power supply and the required clearance (total cabinet footprint should be at least 91.4 cm wide).

• Is this chassis available after the manufacturer discontinues it?

  While the OEM may transition to new platforms, reliable third-party suppliers like Amikon often maintain stocks of EOL hardware to support legacy installations.