Purchase now: Allen-Bradley 1756-A7K ControlLogix Chassis
Purchase now: Atlantechdrives provides you the 1756-A7K, a premium industrial-grade 7-slot chassis meticulously engineered by Rockwell Automation for the highly advanced ControlLogix 1756 programmable automation controller (PAC) platform. Serving as the physical backbone of the control system, this chassis houses the main CPU, power supply, and all associated local I/O and communication modules, routing power and data across its high-speed backplane. The «K» designation in the part number is critically important: it signifies that the entire internal backplane printed circuit board (PCB) has been treated with a factory-applied conformal coating. This specialized, ruggedized protective layer provides immense resistance against harsh environmental factors, including extreme humidity, abrasive airborne contaminants, and corrosive gases (such as hydrogen sulfide or chlorine) frequently found in wastewater treatment plants, chemical refineries, tire manufacturing facilities, and heavy marine applications. By preventing condensation and corrosive agents from shorting the delicate backplane traces, the 1756-A7K guarantees continuous, fail-safe operation in the most punishing industrial environments.
Technical Specifications of the 1756-A7K
The 1756-A7K is built from heavy-duty extruded aluminum to provide structural rigidity and excellent EMI shielding. It is specifically designed to be panel-mounted horizontally inside an industrial electrical control cabinet.
- Part Number: 1756-A7K
- Platform: ControlLogix 1756 System
- Number of Slots: 7
- Environmental Protection: Conformal Coated (Harsh Environment Rated)
- Backplane Current Capacity (1.2V DC): 1.5 A
- Backplane Current Capacity (3.3V DC): 4 A
- Backplane Current Capacity (5.1V DC): 15 A
- Backplane Current Capacity (24V DC): 2.8 A
Expert Tips: Chassis Grounding and Communication Noise
The ControlLogix chassis serves as the central electrical reference point for all modules. Expert Tip: To ensure reliable high-speed data transmission across the backplane and prevent intermittent communication faults (especially on analog modules or EtherNet/IP bridges), you must achieve a perfect chassis ground. Never rely solely on the mounting screws physically touching the metallic backplate of your electrical cabinet. You must run a dedicated, low-impedance grounding wire (minimum 8 AWG solid copper) from the designated grounding lug on the left side of the 1756-A7K chassis directly to the primary ground bus bar of the enclosure. A floating chassis will act as an antenna, absorbing high-frequency EMI generated by nearby Variable Frequency Drives (VFDs) and inducing fatal errors into the PLC processor.
Maintenance: Slot Fillers and Airflow Optimization
Thermal management is absolutely vital for the longevity of ControlLogix systems. If your application only requires 4 modules, leaving 3 slots physically empty in the 1756-A7K is a severe maintenance mistake. Empty slots allow airborne dust to settle directly onto the exposed female backplane pins, and more importantly, they disrupt the precisely engineered thermal airflow path designed to cool the active modules. You must install blank 1756-N2 slot filler modules in every unused slot. This forces the convection air currents to flow correctly through the heat sinks of the active modules, preventing thermal tripping and dramatically extending the lifespan of the electronics.
Frequently Asked Questions (FAQs)
Q: Do I need a special conformal coated power supply to use with the 1756-A7K?
A: Yes. If the factory environment dictates the need for a conformal coated chassis, you should also install a conformal coated power supply (such as the 1756-PA72K) and conformal coated I/O modules (ending in «K») to maintain a uniform, unbroken level of environmental protection across the entire system.
Q: Can I mount the 1756-A7K vertically to save cabinet space?
A: No. Rockwell Automation strictly prohibits vertical mounting of the standard ControlLogix chassis. It relies entirely on passive thermal convection (heat rising) for cooling. Vertical mounting traps the heat generated by the lower modules, causing the upper modules to rapidly overheat and fail.
Do you need more references from this brand? Explore our full catalog of Allen-Bradley here.
This conformal-coated 7-slot chassis provides superior environmental protection and is typically powered by the 1756-PA75 power supply.
