{"product_id":"1756-dnb-allen-bradley-controllogix-devicenet-communication-module","title":"1756-DNB Allen-Bradley ControlLogix DeviceNet Communication Module","description":"\u003ch3\u003e\u003cstrong\u003eOverview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe \u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-DNB Allen-Bradley\u003c\/strong\u003e\u003c\/span\u003e ControlLogix DeviceNet Scanner Module serves as the bridge between ControlLogix rack architectures and field-level DeviceNet networks. Residing in any standard 1756 chassis slot, this network scanner acts as a master\/scanner or slave node, linking controller tag databases with up to 64 DeviceNet field devices (such as motor starters, proximity sensors, pushbuttons, and VFDs). Featuring a front-panel 12 Mbps USB programming port for local configuration and diagnostic access via RSNetWorx for DeviceNet, the unit delivers high-throughput I\/O messaging, explicit data transfers, and seamless backplane routing without burdening the host CPU.\u003c\/p\u003e\n\u003ch3\u003eNetwork Architecture \u0026amp; Communications Topology\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\u003c\/a\u003e 1756 Platform\u003c\/strong\u003e\u003c\/span\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeviceNet Scanner Interface [1756-DNB]:\u003c\/strong\u003e 1-Slot Master\/Slave Network Controller\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaximum Network Node Capacity:\u003c\/strong\u003e Up to 64 Physical DeviceNet Nodes per Channel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSelectable Baud Rates \u0026amp; Distance Limits:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003e125 Kbps up to 500 Meters (Trunkline Limit)\u003c\/li\u003e\n\u003cli\u003e250 Kbps up to 250 Meters\u003c\/li\u003e\n\u003cli\u003e500 Kbps up to 100 Meters\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLocal Programming Interface:\u003c\/strong\u003e 1 x USB Port (Full Speed 12 Mbps Data Transfer)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeviceNet Bus Voltage Requirement:\u003c\/strong\u003e 11 to 25 Vdc Class 2 External Field Power\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eEngineering Specifications \u0026amp; Power Parameters\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eTechnical 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\u003eCatalog Part Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-DNB\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 Communication Module\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBackplane Current Draw (5.1V DC)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e400 mA @ 5.1 Vdc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBackplane Current Draw (24V DC)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0 mA @ 24 Vdc\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eDeviceNet Field Power Current (24V DC)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e60 mA @ 24 Vdc (Current drawn directly from network trunk)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eInternal Power Dissipation\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3.5 Watts Maximum Internal Dissipation\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eThermal Heat Load\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e11.9 BTU\/hr Heat Generation Rating\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eChassis Slot Width\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1 Standard ControlLogix Chassis Slot\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\u003e0.48 kg (1.06 lbs) Physical Module Weight\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eOperational Applications \u0026amp; Field Deployments\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Field Hardware:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003ePowerFlex Series Variable Frequency Drives (VFDs) equipped with 20-COMM-D network adapters.\u003c\/li\u003e\n\u003cli\u003eE300 and E3\/E200 Electronic Overload Relays and ArmorStart distributed motor controllers.\u003c\/li\u003e\n\u003cli\u003eDeviceNet block I\/O blocks (1792D, 1799), photoelectric sensors, limit switches, and valve manifolds.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTarget Industry Deployments:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eAutomotive body shops and high-speed material handling conveyor networks.\u003c\/li\u003e\n\u003cli\u003ePackaging lines, bottling facilities, and palletizing cell automation.\u003c\/li\u003e\n\u003cli\u003eMining, aggregate, and bulk material handling systems utilizing long-distance field bus layouts.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eDiagnostic \u0026amp; Predictive Monitoring Capabilities\u003c\/h3\u003e\n\u003cp\u003eThe \u003cspan style=\"color: #0056b3;\"\u003e\u003cstrong\u003e1756-DNB Allen-Bradley\u003c\/strong\u003e\u003c\/span\u003e module features a two-digit numeric LED status display combined with Module\/Network (MOD\/NET) status indicators. The display outputs alphanumeric error codes (such as Node 00 Fault, Error 72 Bus Off, Error 78 Network Power Lost, or Error 91 Bus Heavy) to accelerate hardware troubleshooting. The scanner firmware actively monitors field trunk voltage levels (detecting drops below 11V DC), measures bus communication error counters, and detects missing slave nodes or baud rate mismatches before communication drops break active control loops.\u003c\/p\u003e\n\u003ch3\u003eGlobal PLC Spare HUB's Insight\u003c\/h3\u003e\n\u003cp\u003eDuring a material handling conveyor upgrade, commissioned field devices suffered intermittent \"Error 72\" bus-off shutdowns when multiple motor starters energized simultaneously. Maintenance staff suspected a faulty scanner board. Our technical support team evaluated the scanner's internal error logs via RSNetWorx and determined that the DeviceNet 24V DC auxiliary power supply experienced voltage drops below 11V DC at the farthest drop line during inductive load surges. Installing a dedicated 24V trunk power tap near the distant nodes stabilized the network immediately without replacing hardware. Always verify bus termination resistors (121-ohm at both trunk ends) and trunkline voltage drop before condemning scanner electronics.\u003c\/p\u003e\n\u003ch3\u003eWarranty, Packaging \u0026amp; Fast Shipping\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Supply Condition:\u003c\/strong\u003e 100% Brand New and Original Factory Sealed Hardware\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWarranty Guarantee:\u003c\/strong\u003e Comprehensive 12-Month Quality Warranty from dispatch date\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOrder Processing Window:\u003c\/strong\u003e Express handling, dispatching within 24 to 48 hours post-payment\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGlobal Express Logistics:\u003c\/strong\u003e Fast door-to-door air freight 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\u003eWhat is the primary cause of an \"Error 78\" code on the front 2-digit LED display?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eError 78 indicates that 24V DC network power is missing from the 5-pin DeviceNet sealed connector on the front panel. Check the external 24V DC power supply, inline fuses, and cable connections leading to the network tap.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow do I configure the baud rate for the 1756-DNB network scanner during initial commissioning?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe scanner baud rate (125K, 250K, or 500K) is software-configured using RSNetWorx for DeviceNet or Studio 5000 module properties. Ensure Auto-Baud is disabled on critical master nodes to maintain consistent startup speed.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan the front USB port be used to browse and configure other nodes across the DeviceNet network?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes. Connecting a laptop to the module's USB port allows RSLinx to bridge through the scanner backplane straight onto the DeviceNet trunk, enabling online configuration and firmware flashes of downstream field devices.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat physical cable guidelines must be followed when running 500-meter networks at 125 Kbps?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eUse thick DeviceNet trunk cable (Class 1) for main runs up to 500 meters. Drop lines to individual nodes must not exceed 6 meters (20 feet) each, with total cumulative drop length kept under 156 meters at 125 Kbps.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow many total bytes of input and output data can a single scanner module handle from its slave scanlist?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe module supports up to 1235 words (2470 bytes) of input data memory and 1235 words (2470 bytes) of output data memory, permitting extensive field I\/O mapping within a single ControlLogix project.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":45013808611510,"sku":"1756-DNB","price":265.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0722\/7863\/8774\/files\/1756-DNB.jpg?v=1787734734","url":"https:\/\/www.plcsparehub.com\/products\/1756-dnb-allen-bradley-controllogix-devicenet-communication-module","provider":"Global PLC Spare Hub","version":"1.0","type":"link"}