{"product_id":"1756-l55-rockwell-automation-controllogix-processor-module","title":"1756-L55 Rockwell Automation ControlLogix Processor Module","description":"\u003ch3\u003e\u003cstrong\u003eOverview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe \u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-L55 Allen-Bradley\u003c\/strong\u003e\u003c\/span\u003e 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.\u003c\/p\u003e\n\u003ch3\u003eConfiguration Architecture Breakdown\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003eAllen-Bradley \u003ca href=\"https:\/\/www.plcsparehub.com\/collections\/allen-bradley-1756-controllogix\"\u003eControlLogix 1756 Platform\u003c\/a\u003e\u003c\/strong\u003e\u003c\/span\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBase Processor [1756-L55]:\u003c\/strong\u003e Logix5555 Execution Engine (Series A)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUser Memory Options:\u003c\/strong\u003e None Internal (Requires 1756-M12, 1756-M13, 1756-M14, or 1756-M15 Non-Volatile Memory Expansion Cards)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBackplane Power Draw:\u003c\/strong\u003e 1.23–1.25 A @ 5.1 Vdc \/ 0.014 A @ 24 Vdc\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCommunication Ports:\u003c\/strong\u003e 1 x RS-232 Serial Port (Supports DF1, DH-485, ASCII)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBackup Power Assembly:\u003c\/strong\u003e Includes 1756-BA1 Lithium Battery Module\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSerial Interface Cables:\u003c\/strong\u003e Compatible with 1756-CP3 or 1747-CP3 Programming Cables\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eTechnical Specifications \u0026amp; Operating Boundaries\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eEngineering Parameter\u003c\/th\u003e\n\u003cth\u003eField Specification Detail\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eManufacturer Name\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003eAllen-Bradley \/ Rockwell Automation\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eFull Catalog Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-L55\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eProduct Line\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003eControlLogix Logix5555 Controller\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eUser Memory Space\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eNone Onboard (Base Unit requires 1756-Mxx Series Memory Module)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eIsolation Voltage Rating\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e30 V Continuous Isolation (Tested at 707 Vdc for 60 seconds)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePower Dissipation\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e5.6 W to 5.7 W Maximum Internal Power Draw\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eThermal Heat Dissipation\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e19.1 BTU\/hr to 19.4 BTU\/hr Heat Load Output\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eHazardous Location Code\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eT4 Temperature Code Rating (IEC 60068 Compliant)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOperating Ambient Window\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0°C to +60°C (32°F to +140°F) Operating Limits\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eStorage Temperature Range\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e-40°C to +85°C (-40°F to +185°F) Storage Window\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eModule Net Weight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0.35 kg (12.5 oz) Net Chassis Weight\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eCompatible Hardware \u0026amp; Operational Deployments\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSystem Components \u0026amp; Accessories:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003e1756-M12 (1.5 MB), 1756-M13 (3.5 MB), and 1756-M14 (7.5 MB) Memory Modules.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-ENBT, 1756-EN2T Ethernet\/IP\u003c\/strong\u003e\u003c\/span\u003e and 1756-DHRIO ControlNet \/ Data Highway Plus modules.\u003c\/li\u003e\n\u003cli\u003eStandard ControlLogix I\/O chassis (1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17) and 1756-PA72 \/ PB72 power supplies.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTarget Industrial Applications:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-speed discrete assembly lines, automotive transfer lines, and conveyor sorting systems.\u003c\/li\u003e\n\u003cli\u003eContinuous batch processing in chemical mixing, pharmaceutical packaging, and water treatment skids.\u003c\/li\u003e\n\u003cli\u003eLegacy migration projects replacing PLC-5 or SLC 500 racks while preserving rack-based communication pathways.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eDiagnostic \u0026amp; Predictive Self-Monitoring Capabilities\u003c\/h3\u003e\n\u003cp\u003eThe \u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-L55 Allen-Bradley\u003c\/strong\u003e\u003c\/span\u003e 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.\u003c\/p\u003e\n\u003ch3\u003eGlobal PLC Spare HUB's Insight\u003c\/h3\u003e\n\u003cp\u003eIn 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 \u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-L55 Allen-Bradley\u003c\/strong\u003e\u003c\/span\u003e 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.\u003c\/p\u003e\n\u003ch3\u003eWarranty, Logistics \u0026amp; Fast Shipping\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Supply State:\u003c\/strong\u003e 100% Brand New and Original Industrial Automation Stock\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWarranty Guarantee:\u003c\/strong\u003e Full 12-Month Quality Warranty from dispatch date\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOrder Processing Window:\u003c\/strong\u003e Fast handling, shipping within 24 to 48 hours post-payment\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExpress Global Courier:\u003c\/strong\u003e Direct door-to-door shipping via FedEx, UPS, and DHL networks\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eEngineering Selection \u0026amp; Operational FAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eCan the Logix5555 base controller execute user programs without installing a memory expansion card?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the procedure if the front-panel \"BAT\" LED illuminates solid yellow during operation?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhich serial cable is required to connect a laptop to the front RS-232 interface port?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eUse 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow many Logix5555 processors can reside in a single ControlLogix chassis?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eMultiple 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.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat firmware revision management steps should engineers consider prior to commissioning?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eEnsure 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.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":45013898657974,"sku":"1756-L55","price":145.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0722\/7863\/8774\/files\/1756-L55M13_9698c3ae-5fa4-4eb1-9684-a520b7b053c2.jpg?v=1787734260","url":"https:\/\/www.plcsparehub.com\/products\/1756-l55-rockwell-automation-controllogix-processor-module","provider":"Global PLC Spare Hub","version":"1.0","type":"link"}