1756-L55 Rockwell Automation ControlLogix Processor Module
Manufacturer: Allen-Bradley
Product No.: 1756-L55
Condition： In stock
Product Type: Processor Module
Product Origin: USA
Payment: T/T, Western Union
Weight: 420g
Shipping port: Xiamen
Warranty: 12 months
Estimate delivery times: 12-26 days (International), 3-6 days (United States).
Return within 30 days of purchase. Duties & taxes are non-refundable.
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Overview
The 1756-L55 Allen-Bradley ControlLogix Logix5555 Processor is a high-performance programmable automation controller designed for centralized control in industrial rack architectures. Belonging to the ControlLogix 1756 family, this base controller unit is supplied without onboard user memory, requiring a dedicated 1756-Mxx expansion memory card (such as 1756-M12, M13, M14, or M15) to execute user application programs. Featuring an integrated RS-232 serial interface and an open-style chassis footprint, it draws power directly from the ControlLogix backplane while supporting multi-processing setups across local and remote I/O chassis.
Configuration Architecture Breakdown
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Allen-Bradley ControlLogix 1756 Platform
- Base Processor [1756-L55]: Logix5555 Execution Engine (Series A)
- User Memory Options: None Internal (Requires 1756-M12, 1756-M13, 1756-M14, or 1756-M15 Non-Volatile Memory Expansion Cards)
- Backplane Power Draw: 1.23–1.25 A @ 5.1 Vdc / 0.014 A @ 24 Vdc
- Communication Ports: 1 x RS-232 Serial Port (Supports DF1, DH-485, ASCII)
- Backup Power Assembly: Includes 1756-BA1 Lithium Battery Module
- Serial Interface Cables: Compatible with 1756-CP3 or 1747-CP3 Programming Cables
Technical Specifications & Operating Boundaries
| Engineering Parameter | Field Specification Detail |
|---|---|
| Manufacturer Name | Allen-Bradley / Rockwell Automation |
| Full Catalog Number | 1756-L55 |
| Product Line | ControlLogix Logix5555 Controller |
| User Memory Space | None Onboard (Base Unit requires 1756-Mxx Series Memory Module) |
| Isolation Voltage Rating | 30 V Continuous Isolation (Tested at 707 Vdc for 60 seconds) |
| Power Dissipation | 5.6 W to 5.7 W Maximum Internal Power Draw |
| Thermal Heat Dissipation | 19.1 BTU/hr to 19.4 BTU/hr Heat Load Output |
| Hazardous Location Code | T4 Temperature Code Rating (IEC 60068 Compliant) |
| Operating Ambient Window | 0°C to +60°C (32°F to +140°F) Operating Limits |
| Storage Temperature Range | -40°C to +85°C (-40°F to +185°F) Storage Window |
| Module Net Weight | 0.35 kg (12.5 oz) Net Chassis Weight |
Compatible Hardware & Operational Deployments
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System Components & Accessories:
- 1756-M12 (1.5 MB), 1756-M13 (3.5 MB), and 1756-M14 (7.5 MB) Memory Modules.
- 1756-ENBT, 1756-EN2T Ethernet/IP and 1756-DHRIO ControlNet / Data Highway Plus modules.
- Standard ControlLogix I/O chassis (1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17) and 1756-PA72 / PB72 power supplies.
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Target Industrial Applications:
- High-speed discrete assembly lines, automotive transfer lines, and conveyor sorting systems.
- Continuous batch processing in chemical mixing, pharmaceutical packaging, and water treatment skids.
- Legacy migration projects replacing PLC-5 or SLC 500 racks while preserving rack-based communication pathways.
Diagnostic & Predictive Self-Monitoring Capabilities
The 1756-L55 Allen-Bradley processor utilizes a comprehensive front-panel LED diagnostic display (RUN, FORCE, BAT, OK, and RS232) to deliver real-time operational feedback. The internal firmware continuously monitors backplane voltage stability, execution task timing, and memory checksum integrity. A red "OK" LED indicates hardware fault conditions, while a solid yellow "BAT" LED alerts maintenance staff that the 1756-BA1 lithium battery voltage has dropped below threshold levels, preventing unexpected program loss during system power shutdowns.
Global PLC Spare HUB's Insight
In legacy system retrofits, maintenance engineers frequently encounter "Major Fault" alarms when hot-swapping older processor modules. During a recent automotive plant overhaul, a failed CPU was replaced with a spare 1756-L55 Allen-Bradley module, but the unit failed to start up. Our technical team diagnosed that the replacement unit lacked an installed 1756-Mxx expansion memory card. Transferring the existing 1756-M13 memory board from the damaged CPU and verifying firmware compatibility via RSLogix 5000 immediately restored full task execution without losing tag databases.
Warranty, Logistics & Fast Shipping
- Product Supply State: 100% Brand New and Original Industrial Automation Stock
- Warranty Guarantee: Full 12-Month Quality Warranty from dispatch date
- Order Processing Window: Fast handling, shipping within 24 to 48 hours post-payment
- Express Global Courier: Direct door-to-door shipping via FedEx, UPS, and DHL networks
Engineering Selection & Operational FAQ
Can the Logix5555 base controller execute user programs without installing a memory expansion card?
No. The base processor contains no user-accessible memory. An expansion memory card (such as a 1756-M12 or 1756-M13) must be snapped into the module's internal connector slot for program download and task execution.
What is the procedure if the front-panel "BAT" LED illuminates solid yellow during operation?
A yellow BAT LED indicates that the 1756-BA1 lithium battery is near depletion. Replace the battery while the rack remains powered up to prevent clearing volatile RAM memory and losing real-time clock data.
Which serial cable is required to connect a laptop to the front RS-232 interface port?
Use an Allen-Bradley 1756-CP3 or 1747-CP3 null-modem serial cable. If modern laptops lack native DB9 serial ports, use a industrial USB-to-RS232 converter with verified FTDI chipsets.
How many Logix5555 processors can reside in a single ControlLogix chassis?
Multiple processors can be installed within the same 1756 chassis. The backplane supports producer/consumer multi-processing, allowing tasks to be distributed across distinct CPUs without external inter-wiring.
What firmware revision management steps should engineers consider prior to commissioning?
Ensure the firmware loaded into the CPU matches the major and minor revision configured in your RSLogix 5000 / Studio 5000 project. Use ControlFlash software over serial or Ethernet/IP pathways to update firmware versions as required.
Tags
Q: Are these parts 100% original and new?
A: Yes. Every component is guaranteed to be 100% original, brand-new, and factory-sealed. We also provide a 12-month comprehensive warranty for your peace of mind.
Q: How fast is the shipping to my country?
A: For in-stock items, we offer same-day dispatch. International express shipping (DHL/FedEx/UPS) typically delivers within 3–5 business days worldwide.
Q: Can I get a formal quotation with shipping costs?
A: Absolutely. Our sales team is ready to provide a detailed Proforma Invoice (PI) including the most competitive shipping rates for your location.
Q: Do you offer discounts for bulk orders?
A: We provide volume-based pricing for large projects or multiple-item orders. Please contact us to get our Best Price Guarantee.
12-Month Comprehensive Warranty
Every part supplied by Global PLC Spare Hub is covered by a 12-month warranty from the date of invoice.
- Coverage: Functional defects and hardware failures under normal operating conditions.
- Commitment: We provide immediate repair, replacement, or a full refund for any verified defective components to minimize your operational downtime.
Returns & Exchange Policy
We offer a 30-day return policy to ensure you receive the exact part your system requires.
- Eligibility: Returns are accepted for uninstalled items in their original, factory-sealed packaging.
- RMA Process: Please contact our support team to obtain a Return Merchandise Authorization (RMA) number before shipping.
- Fast Processing: Refunds or exchanges are processed within 3–5 business days after the returned item passes our technical inspection.
Need Technical Assistance?Not sure if this part is compatible with your system? [Consult our Engineers] before purchasing to ensure 100% compatibility.
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