{"product_id":"allen-bradley-1785-l20b-e-plc-5-processor-module","title":"Allen-Bradley 1785-L20B\/E PLC-5 Processor Module","description":"\u003ch2\u003eAllen-Bradley 1785-L20B\/E PLC-5 Processor Module\u003c\/h2\u003e\n\u003cp\u003eConfigured for logic execution and communication management in PLC-5 control platforms, the \u003cstrong\u003eAllen-Bradley 1785-L20B\/E\u003c\/strong\u003e (\u003cstrong\u003e1785-L20B\u003c\/strong\u003e PLC-5 Processor Module) provides direct physical\/electrical execution through a 1771 I\/O chassis backplane with DH+, Remote I\/O, and serial communication interfaces.\u003c\/p\u003e\n\u003ch3\u003eHardware Specifications\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eModel\u003c\/td\u003e\n\u003ctd\u003e1785-L20B\/E\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eAllen-Bradley\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOrigin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eModule Type\u003c\/td\u003e\n\u003ctd\u003ePLC-5 Processor Module\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Line\u003c\/td\u003e\n\u003ctd\u003ePLC-5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e2.60 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temp\u003c\/td\u003e\n\u003ctd\u003e0 deg C to 60 deg C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower Consumption\u003c\/td\u003e\n\u003ctd\u003e12 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBackplane Current\u003c\/td\u003e\n\u003ctd\u003e2.3 A at 5 VDC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProcessor Type\u003c\/td\u003e\n\u003ctd\u003ePLC-5\/20 Standard Processor\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUser Memory\u003c\/td\u003e\n\u003ctd\u003e2K words battery-backed (16K words maximum memory specification)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCommunication Ports\u003c\/td\u003e\n\u003ctd\u003e1 x DH+, 1 x DH+\/Remote I\/O, 1 x RS-232\/422\/423 serial port\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaximum I\/O Capacity\u003c\/td\u003e\n\u003ctd\u003e1024 points (512 inputs and 512 outputs)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChassis Compatibility\u003c\/td\u003e\n\u003ctd\u003e1771 I\/O chassis\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBattery Type\u003c\/td\u003e\n\u003ctd\u003eLithium battery for memory retention\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eI\/O Scan Time\u003c\/td\u003e\n\u003ctd\u003e10 ms at 57.6 kbps, 7 ms at 115.2 kbps, 3 ms at 230.4 kbps\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStatus Indicators\u003c\/td\u003e\n\u003ctd\u003ePower, fault, and communication LEDs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStorage Temperature\u003c\/td\u003e\n\u003ctd\u003e-40 deg C to +85 deg C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003ePLC-5 Backplane Communication and Firmware Compatibility\u003c\/h3\u003e\n\u003cp\u003eThe 1785-L20B\/E processor module executes PLC-5 control logic through the 1771 chassis backplane interface. The processor manages user program execution, local and remote I\/O scanning, and communication exchange through Data Highway Plus, Remote I\/O, and serial communication channels.\u003c\/p\u003e\n\u003cp\u003eFor Allen-Bradley PLC architecture, the processor depends on backplane bus communication behavior and firmware compatibility between the CPU module, I\/O modules, and communication devices. The module supports I\/O density scaling within PLC-5 system limits and provides multiple communication paths for distributed control configurations.\u003c\/p\u003e\n\u003cp\u003eThe processor supports deterministic PLC-5 network communication through DH+ and Remote I\/O links. Firmware flash compatibility and processor revision verification are required when integrating the module into existing PLC-5 installations.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003eQ: What communication interfaces are available on the 1785-L20B\/E processor module?\u003cbr\u003eA: The module provides DH+, DH+\/Remote I\/O, and RS-232\/422\/423 serial communication interfaces.\u003c\/p\u003e\n\u003cp\u003eQ: How does the 1785-L20B\/E retain the user program during power interruption?\u003cbr\u003eA: The processor uses battery-backed memory with a lithium battery for program retention.\u003c\/p\u003e\n\u003cp\u003eQ: What chassis is required for the 1785-L20B\/E installation?\u003cbr\u003eA: The module is designed for installation in a compatible 1771 I\/O chassis and receives operating power through the chassis backplane.\u003c\/p\u003e\n\u003ch3\u003eField Installation Guidelines\u003c\/h3\u003e\n\u003cp\u003eInstall the 1785-L20B\/E processor module into the assigned 1771 I\/O chassis slot and verify correct backplane connector engagement before system startup. Confirm processor revision compatibility with existing PLC-5 I\/O modules and communication hardware.\u003c\/p\u003e\n\u003cp\u003eConnect DH+, Remote I\/O, and serial communication wiring according to PLC-5 installation requirements. Separate communication cables from high-voltage power wiring and apply appropriate shield grounding practices to reduce electromagnetic interference.\u003c\/p\u003e\n\u003cp\u003eVerify chassis power availability, battery condition, and processor diagnostic LEDs after installation. Confirm I\/O addressing, communication parameters, and user program execution before placing the PLC-5 system into operation.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":43739008368730,"sku":"1785-L20B\/E","price":123.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0612\/4601\/3530\/files\/1785-L20BE2.jpg?v=1785138866","url":"https:\/\/www.plcmasters.com\/products\/allen-bradley-1785-l20b-e-plc-5-processor-module","provider":"PLC Masters Ltd.","version":"1.0","type":"link"}