{"product_id":"allen-bradley-1785-bem-plc-5-backup-communication-module","title":"Allen-Bradley 1785-BEM PLC-5 Backup Communication Module","description":"\u003ch3\u003eDescription\u003c\/h3\u003e\n\u003cp\u003eThe \u003cstrong\u003eAllen-Bradley 1785-BEM\u003c\/strong\u003e is a backup expansion module designed specifically for use with the 1785-BCM series B module in high-reliability industrial automation applications. It serves as an integral part of a redundant architecture, providing the capability to switch two additional configurable communication channels when deployed alongside a PLC-5\/40, PLC-5\/60, or PLC-5\/80 processor.\u003c\/p\u003e\n\u003cp\u003eOperating within a dual-processor system, the \u003cstrong\u003e1785-BEM\u003c\/strong\u003e acts as a hardware bridge that isolates the standby system while enabling the active system to govern remote operations. By maintaining separate primary and secondary control paths, the module facilitates high-speed link synchronization and fault isolation, supporting consistent system up-time and minimized process disturbance during control switchover.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eExpands backup switching capabilities to accommodate up to two additional configurable communication channels.\u003c\/li\u003e\n\u003cli\u003eProvides dedicated physical ports to interface seamlessly with remote I\/O (RIO) links and Data Highway Plus (DH+) networks.\u003c\/li\u003e\n\u003cli\u003eIncludes an integrated customer relay rated at 0.25A at 24V DC resistive for driving external warning devices or status indicators.\u003c\/li\u003e\n\u003cli\u003eUtilizes a user-accessible 6-position switch assembly (SW2) located at the bottom of the module for field configuration of channel operating modes and baud rates.\u003c\/li\u003e\n\u003cli\u003eIntegrates directly with the 1785-BCM module through the local I\/O chassis backplane interface for reliable backplane communication.\u003c\/li\u003e\n\u003cli\u003eFeatures front-panel status indicators (RUN and FLT) for real-time visual hardware diagnostics and switch configuration error detection.\u003c\/li\u003e\n\u003cli\u003eMounts using a standard 1771-WG wiring arm to permit module installation and replacement without disturbing field wiring.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eApplications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eRedundant PLC control environments utilizing Allen-Bradley PLC-5\/40, PLC-5\/60, or PLC-5\/80 processors.\u003c\/li\u003e\n\u003cli\u003eProcess industries requiring high up-time and minimal disturbance switchovers (e.g., oil and gas, chemical processing, water treatment).\u003c\/li\u003e\n\u003cli\u003eData Highway Plus network partitioning and automated link backup routing.\u003c\/li\u003e\n\u003cli\u003eRemote I\/O link switching for critical distributed automation nodes.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eParameter\u003c\/strong\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cstrong\u003eSpecification\u003c\/strong\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eManufacturer\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eAllen-Bradley\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eProduct Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003ePLC-5 Backup Communication Module \/ Expansion Module\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eModel Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1785-BEM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCompatible Master Module\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1785-BCM Series B\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCompatible Processors\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003ePLC-5\/40, PLC-5\/60, PLC-5\/80\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBackplane Current Load\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0.6A at 5V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCustomer Relay Contact Rating\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0.25A at 24V DC (resistive load)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBaud Rate Support (RIO Mode)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e57.6 kbaud, 115.2 kbaud, 230.4 kbaud\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBaud Rate Support (DH+ Mode)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e57.6 kbaud\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eConfigurable Communication Ports\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eChannel 2A, Channel 2B\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eInstallation Guidelines\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eModule Placement:\u003c\/strong\u003e Insert the \u003cstrong\u003e1785-BEM\u003c\/strong\u003e module into the right-most slot of the first I\/O module group within the local I\/O chassis. The module must reside in the exact same module group (as defined by 2-slot addressing) as its companion 1785-BCM module.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChassis Addressing Configuration:\u003c\/strong\u003e Ensure that the local I\/O chassis backplane switch assembly is configured for 1\/2-slot addressing. Failure to select 1\/2-slot addressing when a \u003cstrong\u003e1785-BEM\u003c\/strong\u003e is installed will result in a processor fault.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSwitch Synchronization:\u003c\/strong\u003e The configuration switches on switch assembly SW2 must be set to the identical physical positions on both the primary and secondary \u003cstrong\u003e1785-BEM\u003c\/strong\u003e modules. Discrepancies between the two modules will cause the green RUN indicator to blink on the secondary unit and can prevent system switchover.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eElectrostatic Discharge (ESD) Protection:\u003c\/strong\u003e Wear an approved grounded wrist strap and avoid touching backplane connector pins or circuit components when setting switch parameters or handling the unit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChassis Keying:\u003c\/strong\u003e Utilize plastic keying bands on the backplane connector to guard against incorrect module insertion. Place the keying bands between positions 8 and 10, and between positions 34 and 36.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInductive Load Suppression:\u003c\/strong\u003e The customer relay contacts are rated for resistive loads. If the relay is utilized to switch external inductive loads, additional external surge suppression devices must be installed to protect the internal contacts.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":52695187194219,"sku":"1785-BEM","price":100.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0953\/3227\/0443\/files\/allen-bradley-1785-bem-backup-communication-module-riugat4aaxm_8b03c088-eecf-437f-a257-0c0a8df7f7b0.jpg?v=1766114499","url":"https:\/\/www.plcprotech.com\/products\/allen-bradley-1785-bem-plc-5-backup-communication-module","provider":"PLC ProTech Ltd.","version":"1.0","type":"link"}