{"product_id":"allen-bradley-1785-bcm-b-backup-communication-module","title":"Allen-Bradley 1785-BCM\/B Backup Communication Module","description":"\u003ch2\u003eAllen-Bradley 1785-BCM\/B Backup Communication Module\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eAllen-Bradley 1785-BCM\/B\u003c\/strong\u003e, also cataloged as the \u003cstrong\u003e1785-BCM\/B\u003c\/strong\u003e Backup Communication Module, operates as a dedicated hardware component for redundant PLC-5 processor coordination within 1771 I\/O chassis platforms.\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-BCM\/B\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\u003eUnited States\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e0.6 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temp\u003c\/td\u003e\n\u003ctd\u003e0 to 60 deg C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower Consumption\u003c\/td\u003e\n\u003ctd\u003e5 VDC backplane current: 1.0 A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Type\u003c\/td\u003e\n\u003ctd\u003eBackup Communication Modules\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatible Processors\u003c\/td\u003e\n\u003ctd\u003ePLC-5\/15 Series B, PLC-5\/20, PLC-5\/25, PLC-5\/30, PLC-5\/40, PLC-5\/60\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInstallation Location\u003c\/td\u003e\n\u003ctd\u003e1771 I\/O chassis local slot\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCommunication Interface\u003c\/td\u003e\n\u003ctd\u003eHigh-Speed Serial Link (HSSL)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCommunication Speed\u003c\/td\u003e\n\u003ctd\u003e1.2 Megabaud\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCustomer Relay Output\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\u003eKeying Locations\u003c\/td\u003e\n\u003ctd\u003eBetween 8-10 and 34-36\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWiring Arm Compatibility\u003c\/td\u003e\n\u003ctd\u003e1771-WG\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStorage Temperature\u003c\/td\u003e\n\u003ctd\u003e-40 to 85 deg C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelative Humidity\u003c\/td\u003e\n\u003ctd\u003e5-95% non-condensing\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCertifications\u003c\/td\u003e\n\u003ctd\u003eUL Listed, CSA Class 1 Division 2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiagnostics\u003c\/td\u003e\n\u003ctd\u003eStatus indicators and system status word bits\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eEtherNet\/IP and PLC Communication Interface Characteristics\u003c\/h3\u003e\n\u003cp\u003eThe 1785-BCM\/B provides PLC-5 redundancy coordination through a dedicated backup communication path between primary and secondary processors. The module exchanges processor status information and manages control transfer conditions through the High-Speed Serial Link interface.\u003c\/p\u003e\n\u003cp\u003eThe module supports bumpless switchover operation by maintaining communication synchronization between paired PLC-5 processors. Within PLC-5 control architectures, the module manages redundancy state monitoring, processor health detection, and backup communication functions without adding I\/O capacity or processor execution resources.\u003c\/p\u003e\n\u003cp\u003eThe 1785-BCM\/B integrates with Allen-Bradley PLC-5 systems through the 1771 chassis backplane interface. Firmware and configuration compatibility must match the installed PLC-5 processor family and redundancy architecture.\u003c\/p\u003e\n\u003ch3\u003eFirmware and PLC-5 Redundancy Interface Characteristics\u003c\/h3\u003e\n\u003cp\u003eThe module operates within legacy PLC-5 redundant control systems and uses dedicated backplane communication for module coordination. The HSSL communication link provides data exchange between paired controllers at 1.2 Megabaud.\u003c\/p\u003e\n\u003cp\u003eSystem status word diagnostics and front-panel indicators provide hardware-level monitoring of communication state and fault conditions. Proper chassis keying and wiring arm installation are required to maintain correct module positioning and field connection.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003eQ: What PLC-5 processors are compatible with the 1785-BCM\/B?\u003cbr\u003eA: The module supports PLC-5\/15 Series B, PLC-5\/20, PLC-5\/25, PLC-5\/30, PLC-5\/40, and PLC-5\/60 processors.\u003c\/p\u003e\n\u003cp\u003eQ: What is the backplane power requirement of the 1785-BCM\/B?\u003cbr\u003eA: The module requires 1.0 A at 5 VDC from the 1771 chassis backplane.\u003c\/p\u003e\n\u003cp\u003eQ: Does the 1785-BCM\/B provide additional I\/O or processing capability?\u003cbr\u003eA: No. The module provides backup communication and redundancy coordination functions only.\u003c\/p\u003e\n\u003ch3\u003eField Installation Guidelines\u003c\/h3\u003e\n\u003cp\u003eInstall the 1785-BCM\/B in a compatible 1771 I\/O chassis slot using the specified keying positions and 1771-WG wiring arm. Confirm that the chassis power supply can support the module backplane current requirement before installation.\u003c\/p\u003e\n\u003cp\u003eConnect redundancy communication wiring according to the PLC-5 backup system configuration. Keep communication wiring separated from high-voltage power conductors and sources of electromagnetic interference.\u003c\/p\u003e\n\u003cp\u003eVerify module status indicators after power-up and confirm correct processor synchronization through PLC-5 diagnostic status information. Maintain environmental conditions within the specified temperature and humidity limits during operation.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":43738008223834,"sku":"1785-BCM\/B","price":123.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0612\/4601\/3530\/files\/1785-BCMB2.jpg?v=1785133410","url":"https:\/\/www.plcmasters.com\/products\/allen-bradley-1785-bcm-b-backup-communication-module","provider":"PLC Masters Ltd.","version":"1.0","type":"link"}