{"product_id":"1771-a4b-allen-bradley-brand-new-24a-backplane-chassis","title":"1771-A4B Allen-Bradley Brand New 24A Backplane Chassis","description":"\u003ch3\u003eProduct Overview\u003c\/h3\u003e\n\u003cp\u003eThe Allen-Bradley 1771-A4B operates as a high-capacity, heavy-duty 16-slot universal input\/output chassis designed for the classic Rockwell Automation PLC-5 control platform. This backbone enclosure provides the physical mounting structure, data communication pathways, and regulated power distribution lines necessary to operate complex industrial automation systems. Featuring a rugged backplane rated for up to 24 Amps of continuous current at 5.25 VDC, the 1771-A4B links central processor modules, remote I\/O adapters, and high-density discrete or analog 1771 modules together. Heavy manufacturing, automotive assembly lines, and water treatment utilities utilize this physical matrix to orchestrate thousands of distributed field sensors and machinery loops from a centralized control cabinet location.\u003c\/p\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr class=\"firstRow\"\u003e\n\u003ctd\u003e\u003cstrong\u003eParameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eSpecification Value\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eManufacturer\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eAllen-Bradley \/ Rockwell Automation\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eModel Number\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e1771-A4B (1771-A4BB)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eAlternate Part Number ID\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e96814809\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eProduct Classification\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eUniversal I\/O Chassis \/ PLC Rack\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eControl System Compatibility\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eAllen-Bradley PLC-5 Systems and 1771 I\/O Components\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eTotal Physical Slots\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e16 dedicated hardware slots\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eMaximum Backplane Current\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e24 Amps continuous delivery capacity\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eNominal Backplane Voltage\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e5.25 VDC regulated logic level\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eAddressing Capabilities\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eSupports 2-slot, 1-slot, and 1\/2-slot addressing modes\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eMaximum Configured Racks\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eUp to 4 logical I\/O racks using 1\/2-slot addressing profiles\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eModule Keying Requirements\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eAccepts 36 plastic keying bands for hardware enforcement\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eDedicated Processor Slot\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eLeftmost hardware slot position only\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eDedicated Adapter Slot\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eLeftmost hardware slot position only\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003ePeripheral Module Slots\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eSlots 1 through 15 accept communication, I\/O, or power cards\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eMounting Orientation\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eRear panel mounting (backplate screw secured configuration)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003ePhysical Chassis Dimensions\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e482 mm x 178 mm x 292 mm (19.0 in x 7.0 in x 11.5 in)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eNet Hardware Chassis Mass\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e6.07 kg (13.38 lbs) unpopulated state\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eOperating Thermal Window\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e0 to +60 degrees Celsius\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eStorage Temperature Limits\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e-40 to +85 degrees Celsius dry ambient\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eEnvironmental Relative Humidity\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e5 percent to 95 percent relative humidity (non condensing)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eRegulatory Compliance Profiles\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eUL, CSA, CE compliant structural construction\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eProcurement Supply Profile\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e100 percent Brand New and Original in Factory Packing\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eEngineering Advantages\u003c\/h3\u003e\n\u003ch3\u003eHigh-Current 24A Backplane Prevents Intermittent Logic Drops\u003c\/h3\u003e\n\u003cp\u003ePopulating a large 16-slot chassis with high-density analog modules, thermal sensors, and remote network scanners creates massive electrical loading on standard 5V supply paths. The 1771-A4B resolves this issue by incorporating a reinforced 24 Amp bus network across its entire physical length. This heavy copper backplane topology keeps supply voltages locked within strict tolerances under maximum load conditions, eliminating the thermal stress, signaling jitter, and unexpected processor drops that common low-amp legacy frames generate.\u003c\/p\u003e\n\u003ch3\u003eFlexible Half-Slot Addressing Multiplies Channel Population Capacity\u003c\/h3\u003e\n\u003cp\u003eTo optimize data density without requiring expansive physical footprint re-engineering, the 1771-A4B backplane infrastructure supports 1\/2-slot addressing configurations. This flexible grouping format maps any pair of physical chassis slots into a single input\/output image byte, effectively allowing a single 16-slot frame to supervise up to 4 complete logical I\/O racks. This configuration maximizes processing density inside existing industrial wall enclosures, cutting additional cabinet purchase costs.\u003c\/p\u003e\n\u003ch3\u003eForm-Enforced Plastic Keying Strips Block Incorrect Module Swapping\u003c\/h3\u003e\n\u003cp\u003eField technicians executing rapid repairs under plant breakdown conditions can accidentally slide a high-voltage AC input module into a slot wired for low-voltage analog transmitters, risking catastrophic component destruction. The 1771-A4B chassis provides designated keying tracks along its backplane connector border that accept up to 36 precise plastic keying bands. These physical indicators match specialized notches on individual 1771 cards, preventing unauthorized or mismatched modules from seating into live slots.\u003c\/p\u003e\n\u003ch3\u003eFAQs\u003c\/h3\u003e\n\u003cul class=\"list-paddingleft-2\"\u003e\n\u003cli\u003e\n\u003cp\u003eWhich external power supply options interface directly with the 1771-A4B chassis?\u003c\/p\u003e\n\u003cp\u003eThe 1771-A4B chassis does not include an onboard power supply and requires an external source to energize the 5.25 VDC logic bus. You can insert an in-rack power supply module (such as the 1771-P4R or 1771-P7 rated for 3 to 8 Amps) directly into any slot position excluding the leftmost slot. Alternatively, for maximum slot availability, you can wire external panel-mounted power supplies rated from 6.5 to 16 Amps directly to the terminal connections located on the chassis chassis.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eHow do the slot allocation rules restrict where I can mount a processor or communication adapter?\u003c\/p\u003e\n\u003cp\u003eThe 1771-A4B strictly reserves the leftmost slot position for the master system coordinator. You must insert either your main PLC-5 processor card or a remote I\/O adapter module (such as a 1771-ASB card linking back to a master PLC via a remote data highway) into this primary location. Peripheral components—such as standard digital inputs, analog outputs, network scanners, and in-rack power cards—can occupy all other slots from slot 1 through slot 15.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eWhat special ground bonding hardware comes included for electrical safety?\u003c\/p\u003e\n\u003cp\u003eTo repel severe electromagnetic fields (EMI) generated by heavy manufacturing motors and high-voltage contactors, each brand new 1771-A4B shipping kit includes dedicated structural grounding hardware. The kit provides one cup washer, one star washer, four flat washers, and two #10 to 32 nuts fitted with captive lock washers. You must bond this terminal directly to the main copper grounding bus bar of your control enclosure to ensure stable backplane signaling.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Allen Bradley","offers":[{"title":"Default Title","offer_id":43399643005018,"sku":"1771-A4B","price":99.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0710\/5957\/0778\/files\/250._5d0fc7dc-f23f-4bd8-b1a1-d392ac79beaf.jpg?v=1779330664","url":"https:\/\/www.spareoil.com\/products\/1771-a4b-allen-bradley-brand-new-24a-backplane-chassis","provider":"SpareOil Automation","version":"1.0","type":"link"}