{"product_id":"allen-bradley-1785-bem-backup-communications-expansion-module","title":"Allen-Bradley 1785-BEM Backup Communications Expansion Module","description":"\u003ch2\u003eAllen-Bradley 1785-BEM Backup Communications Expansion Module\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eAllen-Bradley 1785-BEM\u003c\/strong\u003e, also cataloged as the \u003cstrong\u003e1785-BEM\u003c\/strong\u003e Backup Communications Expansion Module, operates as a dedicated hardware component for communication channel switching and backup control execution within PLC-5 processor systems. The module interfaces with 1785-BCM Series B modules through the I\/O chassis backplane and provides two configurable communication links for DH+ and Remote I\/O networks.\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-BEM\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\u003eBackup Communications Expansion 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\u003e0.99 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003e4.5 x 12.4 x 6.3 in\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower Consumption\u003c\/td\u003e\n\u003ctd\u003e0.6 A at 5 VDC backplane current\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBackplane Requirement\u003c\/td\u003e\n\u003ctd\u003e0.6 A at 5 VDC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCommunication Interfaces\u003c\/td\u003e\n\u003ctd\u003e2 communication links\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNetwork Support\u003c\/td\u003e\n\u003ctd\u003eData Highway Plus (DH+) and Remote I\/O\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaximum Modules Per System\u003c\/td\u003e\n\u003ctd\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eExternal Power Supply\u003c\/td\u003e\n\u003ctd\u003eNone required\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStatus Indicators\u003c\/td\u003e\n\u003ctd\u003eOne diagnosis\/status LED per channel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelay Contact Rating\u003c\/td\u003e\n\u003ctd\u003e0.25 A at 24 VDC resistive load\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSignal Delay\u003c\/td\u003e\n\u003ctd\u003eAC Off: 29 +\/- 8 ms; DC Off: 30 +\/- 7 ms\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003ePLC-5 Backup Communication Channel Switching\u003c\/h3\u003e\n\u003cp\u003eThe 1785-BEM module provides additional communication channel switching capability when installed with a 1785-BCM Series B module in PLC-5\/40, PLC-5\/60, or PLC-5\/80 processor configurations. The module communicates through the PLC chassis backplane and supports switching of configurable communication paths.\u003c\/p\u003e\n\u003cp\u003eThe module contains two communication ports assigned for Data Highway Plus or Remote I\/O link operation. The SW2 switch assembly defines the communication function assignment for Channels 2A and 2B.\u003c\/p\u003e\n\u003cp\u003eThe local backplane interface transfers communication status and control information between the 1785-BEM and the associated 1785-BCM module. The customer relay output provides external device switching capability, with inductive loads requiring additional suppression components.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003eQ: What communication networks can the 1785-BEM interface with?\u003cbr\u003eA: The 1785-BEM provides two configurable communication links supporting Data Highway Plus (DH+) and Remote I\/O network connections.\u003c\/p\u003e\n\u003cp\u003eQ: What is the backplane current requirement of the 1785-BEM?\u003cbr\u003eA: The module requires 0.6 A from the 5 VDC I\/O chassis backplane supply.\u003c\/p\u003e\n\u003cp\u003eQ: Does the 1785-BEM require an external power supply?\u003cbr\u003eA: No external power supply is required. The module receives operating power through the PLC-5 chassis backplane interface.\u003c\/p\u003e\n\u003ch3\u003eField Installation Guidelines\u003c\/h3\u003e\n\u003cp\u003eInstall the 1785-BEM module in the designated PLC-5 I\/O chassis slot and verify proper seating of the module edge connector before operation. Confirm compatibility with the installed 1785-BCM Series B backup configuration.\u003c\/p\u003e\n\u003cp\u003eConfigure the SW2 switch assembly according to the required DH+ or Remote I\/O communication assignment before applying system power. Connect communication wiring using appropriate shielded industrial cable practices and route communication cables separately from high-voltage power conductors to reduce electrical interference.\u003c\/p\u003e\n\u003cp\u003eFor customer relay connections, install suppression devices when switching inductive loads. Verify chassis grounding, cable shield termination, and backplane power availability according to the PLC-5 installation documentation.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":43738684194906,"sku":"1785-BEM","price":123.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0612\/4601\/3530\/files\/1785-BEM2.jpg?v=1785135953","url":"https:\/\/www.plcmasters.com\/products\/allen-bradley-1785-bem-backup-communications-expansion-module","provider":"PLC Masters Ltd.","version":"1.0","type":"link"}