Allen-Bradley 1756-A7K ControlLogix 7-Slot Chassis | Replacement, Equivalent & Selection Guide
The Allen-Bradley 1756-A7K is a 7-slot ControlLogix chassis designed for Rockwell Automation’s ControlLogix platform. It provides a robust, modular backplane for mounting ControlLogix I/O, communication, and controller modules in demanding industrial environments. This page serves as a comprehensive selection, replacement, and compatibility reference for engineers and procurement teams sourcing the 1756-A7K or evaluating alternatives.
Technical Specifications
- Part Number: 1756-A7K
- Series: ControlLogix (1756 Series)
- Manufacturer: Allen-Bradley / Rockwell Automation
- Number of Slots: 7
- Backplane Type: ControlLogix Backplane
- Power Supply Compatibility: 1756-Pxx series (e.g., 1756-PA72, 1756-PB72, 1756-PC75)
- Operating Temperature: 0 °C to 60 °C (32 °F to 140 °F)
- Storage Temperature: -40 °C to 85 °C
- Relative Humidity: 5% to 95% non-condensing
- Mounting: DIN rail or panel mount
- Dimensions (H × W × D): Approx. 146 × 250 × 144 mm
- Weight: Approx. 500 g (chassis only)
- Certifications: UL, CE, cUL
- Country of Origin: USA
Compatible Replacement & Equivalent Models
When the 1756-A7K is unavailable or end-of-life, the following models are commonly evaluated as replacements or equivalents. Always verify electrical and mechanical compatibility before substitution.
- 1756-A4K — 4-slot ControlLogix chassis; suitable when fewer module slots are required
- 1756-A10K — 10-slot ControlLogix chassis; drop-in backplane upgrade for expanded I/O
- 1756-A13K — 13-slot chassis for high-density applications
- 1756-A17K — 17-slot chassis for maximum module density
- 1756-A7 — Standard (non-K) 7-slot chassis; verify power supply and keying compatibility
- Third-party compatible chassis — Select vendors offer 1756-series compatible chassis; confirm backplane signaling and UL listing before use
Note: The “K” suffix denotes a conformal-coated variant for harsh or high-humidity environments. Substituting a non-K chassis in such environments may void certifications.
Why Choose the Original 1756-A7K
- Conformal Coating: Factory-applied coating protects against moisture, dust, and corrosive atmospheres — critical for food & beverage, chemical, and outdoor enclosure applications
- Guaranteed Backplane Compatibility: Engineered and tested by Rockwell Automation for full signal integrity with all 1756-series modules
- Long-term Support: Covered under Rockwell’s product lifecycle and firmware update roadmap
- Regulatory Compliance: UL 508, CE, and cUL listed — simplifies panel certification
- Reduced Integration Risk: Eliminates compatibility unknowns associated with third-party alternatives
Typical Applications
- Discrete manufacturing automation (automotive assembly, packaging lines)
- Process control in chemical, oil & gas, and water treatment plants
- Food & beverage production with washdown or high-humidity requirements
- Pharmaceutical manufacturing under GMP environments
- Power generation and utilities SCADA integration
- Material handling and conveyor systems
System Compatibility
- Controllers: All 1756-Lxx ControlLogix controllers (e.g., 1756-L71, 1756-L73, 1756-L83E)
- I/O Modules: Full 1756-series digital and analog I/O
- Communication Modules: 1756-EN2T (EtherNet/IP), 1756-DNB (DeviceNet), 1756-CN2 (ControlNet), 1756-DHRIO
- Power Supplies: 1756-PA72, 1756-PB72, 1756-PC75, 1756-PH75
- Software: Studio 5000 Logix Designer v21 and above; RSLogix 5000 v16+
Selection Guide
Use the following criteria to select the correct ControlLogix chassis for your application:
- Slot count: Count all required modules (controller + I/O + comms) and add 1–2 spare slots for future expansion. The 1756-A7K suits small-to-mid-size control panels.
- Environment rating: Choose the K-suffix (conformal-coated) variant for humidity >85%, chemical exposure, or outdoor enclosures. Use standard (non-K) for climate-controlled panels.
- Power supply voltage: Match chassis to available supply — PA72 (120/240 VAC), PB72 (24 VDC), PC75 (24 VDC high-capacity), PH75 (125 VDC).
- Redundancy: For redundant controller configurations, pair with a second chassis and 1756-RM2/A redundancy module.
- Chassis size comparison: A4K (4-slot) → A7K (7-slot) → A10K (10-slot) → A13K (13-slot) → A17K (17-slot)
Quality Assurance & Sourcing
- All units sourced through authorized distributors or verified surplus channels
- Each unit inspected for physical integrity, label authenticity, and date code consistency
- Serialization and traceability documentation available upon request
- Warranty: 12 months from shipment date against manufacturing defects
- Returns accepted within 30 days for unused, uninstalled units in original packaging
How to Order
- Confirm part number: 1756-A7K (conformal-coated, 7-slot)
- Specify required quantity
- Contact us via email or phone for lead time and pricing
- Provide project details for volume discount eligibility
- Receive proforma invoice → confirm payment → shipment with tracking
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Replacement & Compatibility FAQ
Q: Can I replace a 1756-A7 with a 1756-A7K?
A: Yes, the 1756-A7K is a direct form-fit-function replacement for the 1756-A7 with the addition of conformal coating. No wiring or software changes are required.
Q: Is the 1756-A7K compatible with older ControlLogix controllers like the 1756-L55?
A: Yes, the chassis backplane is backward compatible with legacy 1756-series controllers, though firmware and software version constraints may apply.
Q: Can I mix K and non-K modules in the same chassis?
A: Yes. The K designation applies only to the chassis coating; all standard 1756-series modules are mechanically and electrically compatible.
Q: What is the lead time for the 1756-A7K?
A: Stock availability varies. Contact us for current lead time — we typically ship in-stock units within 1–3 business days.
Q: Do you provide certificates of conformance (CoC)?
A: Yes, CoC and inspection reports are available upon request for all orders.
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