Allen-Bradley 1756 ControlLogix Modules: 1756-A13 13-Slot Chassis,

Technical Dossier

Product Details And Specifications

Allen-Bradley 1756 ControlLogix Series Technical Notes

The Allen-Bradley 1756 ControlLogix platform is Rockwell Automation's flagship programmable automation controller (PAC) architecture, deployed across the full spectrum of heavy industrial environments including petrochemical refineries, nuclear power generation facilities, offshore oil & gas platforms, pulp and paper mills, and large-scale water treatment infrastructure. The 1756-A13, a 13-slot chassis, is one of the most widely specified backplane configurations in this series, providing sufficient slot density for mid-to-large control node builds without requiring multi-chassis expansion in the majority of process cell applications.

The ControlLogix 1756 series holds dominant installed-base status globally. Facilities commissioned between 1997 and the present day routinely operate 1756-series hardware, and the platform's backward-compatible backplane architecture means that chassis such as the 1756-A13 remain in active service alongside current-generation processors and I/O modules. This longevity creates a sustained demand for spare chassis, replacement modules, and lifecycle extension support — the core competency of DriveKNMS.

The Evolution of 1756 ControlLogix Architecture

The ControlLogix platform was introduced in 1997 as a successor to the PLC-5 and SLC 500 families, establishing a modular, producer/consumer network architecture over the ControlNet and later EtherNet/IP backbones. The chassis-based design — with the 1756-A4 (4-slot), 1756-A7 (7-slot), 1756-A10 (10-slot), 1756-A13 (13-slot), and 1756-A17 (17-slot) as the primary form factors — allowed engineers to scale control nodes precisely to I/O count requirements.

Early-generation processors (1756-L1, 1756-L55) used removable memory cards and had limited task capacity. The introduction of the 1756-L6x series brought integrated nonvolatile memory and expanded task scheduling. The current 1756-L8x generation (e.g., 1756-L83E, 1756-L85E) introduced dual-port EtherNet/IP, CIP Security, and significantly expanded memory and I/O tree capacity.

Compatibility note: All processor generations are mechanically compatible with all 1756 chassis variants, including the 1756-A13. However, firmware and software (Studio 5000 Logix Designer) version alignment must be verified when mixing processor generations within a multi-chassis system. Chassis manufactured prior to Series B may exhibit backplane communication limitations when paired with L8x-generation processors at high I/O scan rates.

1756 ControlLogix Full Catalog & Functionalities (SKU List)

Chassis

• 1756-A4: 4-slot ControlLogix chassis, compact node configuration
• 1756-A7: 7-slot ControlLogix chassis, standard small-node build
• 1756-A10: 10-slot ControlLogix chassis, mid-density I/O node
• 1756-A13: 13-slot ControlLogix chassis, high-density process cell standard
• 1756-A17: 17-slot ControlLogix chassis, maximum single-chassis slot count

Power Supplies

• 1756-PA72: 120/240VAC input power supply, 10A backplane output
• 1756-PB72: 18–32VDC input power supply, 10A backplane output
• 1756-PA75R: Redundant-rated 120/240VAC power supply for high-availability systems
• 1756-PB75R: Redundant-rated 18–32VDC power supply

Controllers (CPUs)

• 1756-L71: ControlLogix 5570 controller, 2MB memory, single EtherNet/IP port
• 1756-L73: ControlLogix 5570 controller, 8MB memory
• 1756-L83E: ControlLogix 5580 controller, 20MB memory, dual-port EtherNet/IP
• 1756-L85E: ControlLogix 5580 controller, 40MB memory, dual-port EtherNet/IP

Digital Input (DI) Modules

• 1756-IB16: 16-point 10–31.2VDC digital input module
• 1756-IB32: 32-point 10–31.2VDC digital input, high-density
• 1756-IA16: 16-point 74–132VAC digital input module

Digital Output (DO) Modules

• 1756-OB16E: 16-point 10–31.2VDC electronically fused digital output
• 1756-OA16: 16-point 74–132VAC digital output module

Analog Input (AI) Modules

• 1756-IF16: 16-channel single-ended analog input, ±10V / 0–20mA
• 1756-IF8: 8-channel differential analog input module

Analog Output (AO) Modules

• 1756-OF8: 8-channel analog output, voltage and current configurable

Communication Adapters

• 1756-EN2T: EtherNet/IP communication module, single copper port
• 1756-EN2TR: EtherNet/IP module with dual-port DLR (Device Level Ring) support
• 1756-CN2R: ControlNet redundant media communication module
• 1756-DNB: DeviceNet scanner module for legacy device integration

Sourcing Hard-to-Find & Obsolete 1756 ControlLogix Parts

A significant portion of the global 1756 ControlLogix installed base operates hardware that Rockwell Automation has transitioned to End-of-Life (EOL) or discontinued status. This includes early-generation processors (1756-L1, 1756-L55 series), legacy communication modules (1756-CNB, 1756-DHRIO), and original-series chassis with pre-Series B backplane revisions.

DriveKNMS maintains a dedicated inventory of tested surplus and refurbished 1756-series components to support facilities that cannot execute full system migrations due to capital constraints, regulatory freeze periods, or production continuity requirements. Our sourcing network covers:

• Discontinued chassis variants including pre-Series B 1756-A13 units
• Legacy processor modules with verified firmware compatibility documentation
• EOL communication adapters for ControlNet and DeviceNet legacy networks
• Matched power supply replacements for redundant system configurations

Quality Control for the 1756 ControlLogix Range

The 1756 ControlLogix chassis and backplane architecture presents specific test requirements that differ from standard I/O module verification. DriveKNMS applies the following test protocol to all 1756-series hardware prior to dispatch:

• Backplane continuity test: Each slot position on the 1756-A13 chassis is verified for full backplane bus signal integrity using a dedicated ControlLogix test fixture. Open or degraded backplane segments are flagged and the chassis is rejected.
• Power supply load test: PA72/PB72 and redundant-rated supplies are tested under full rated backplane load (10A) for a minimum 30-minute burn-in period. Output ripple and regulation are measured against Rockwell published specifications.
• Processor functional verification: CPU modules are tested with a known-good project file covering all task types (continuous, periodic, event). Memory integrity, I/O tree scan, and communication port function are verified.
• Communication module loopback test: EN2T, EN2TR, and CN2R modules are tested for full-duplex communication, port negotiation, and CIP connection establishment before release.
• Firmware version documentation: All processor and communication modules are shipped with a firmware version record to support customer compatibility planning.