Features:
- Dual configurable communication channels supporting Data Highway Plus and Remote I/O redundancy
- Seamless integration with 1785-BCM module for extended backup communication capability
- Built-in relay switching and status indicators for reliable system switchover and monitoring
The Allen-Bradley 1785-BEM is a critical component in PLC-5 backup architectures, extending communication redundancy for industrial control systems. It works alongside the 1785-BCM module to provide additional communication channels that ensure continuous operation even during system faults. This capability is essential in industries where downtime can result in significant operational or financial impact. The 1785-BEM allows engineers to design systems with higher availability and fault tolerance. Its integration into PLC-5 platforms supports long-term reliability in legacy automation environments.
From a functional perspective, the 1785-BEM enables communication across Data Highway Plus and Remote I/O networks with flexible configuration options. The module’s switch assembly allows users to define communication modes and parameters based on system requirements. Internal relays automatically manage channel switching between primary and secondary processors, ensuring smooth transitions during failover events. The 1785-BEM also supports communication synchronization through high-speed links, enhancing coordination between redundant systems. These features contribute to stable and predictable system behavior.
In real-world applications, the Allen-Bradley 1785-BEM is used in systems that require continuous process control and minimal downtime. Its compatibility with PLC-5 processors and integration within 1771 I/O chassis make it suitable for upgrading or maintaining existing installations. The module operates reliably under industrial environmental conditions and meets recognized certification standards. Installation practices emphasize separation of local and remote I/O to ensure proper backup functionality. The 1785-BEM therefore provides a dependable solution for maintaining communication integrity in redundant PLC-5 systems.
The 1785-BEM Allen-Bradley PLC-5 Backup Communication Module may still be available for purchase and support from Apter Power beyond End-Of-Life (EOL) by the manufacturer (OEM).
Allen-Bradley 1785-BEM PLC-5 Backup Communication Module Manuals,Datasheets,Link
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
Allen-Bradley 1785-BEM PLC-5 Backup Communication Module Specs
General
- Manufacturer Allen-Bradley
- Model 1785-BEM
- Condition New Original ready stock
- Product Family 1785-BCM
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description. All prices are shown in USD.
- Seamless Dual-Machine Hot Standby Switching: As core hardware, this module, in conjunction with the main module, can smoothly switch control to the standby system within milliseconds in the event of a sudden failure or power outage of the main PLC-5 controller, achieving a seamless switchover.
- High-Speed Backplane Data Synchronization: Utilizing the dedicated internal backplane bus of the 1771 rack, it performs high-frequency bidirectional data synchronization with the adjacent 1785-BCM module, ensuring high consistency between the process image areas (I/O states, register variables) of the main and standby controllers.
- Independent Relay Action: An onboard hardware customer relay interface, rated at 24V DC / 0.25A, is dedicated to directly outputting hard-wired signals to trigger external alarms or disconnect physical circuits during main/standby system switching.
- Automatic Main/Standby Status Determination: After power-on, the module automatically and dynamically determines whether it is in "Primary" or "Secondary" operating mode based on hardware jumpers and the response status of the peer system.
- Metallurgical and Papermaking Continuous Production Lines: In steel plant heating furnaces or papermaking machine control systems where unexpected shutdowns are strictly prohibited and would result in significant economic losses, a dual-machine hot standby architecture provides 24/7 uninterrupted operation protection.
- Large-scale Water Treatment and Pumping Station Centralized Control: Applied to remote distributed I/O systems in municipal wastewater treatment plants and water supply pumping stations, the 1785-BEM network bridging capability enables uninterrupted data acquisition from control nodes scattered across several kilometers.
- Petrochemical Long-Distance Pipeline Monitoring Systems: Deployed in critical valve chambers or pressurization stations of oil and gas pipelines, even if a rack or central processing unit is damaged due to lightning strikes or other failures, the backup system can immediately take over remote I/O control.
- Power Plant Auxiliary Workshop Control System (BOP): In highly available automated systems such as chemical makeup water, ash removal, and coal conveying, it serves as a physical communication bridge for seamless redundant connection between the PLC-5 system and the upper-level data network (DH+).
- Multi-link Remote I/O Bridging: Provides dedicated communication ports for simultaneous or independent connection of dual high-speed Remote I/O links, ensuring that the primary and backup systems can simultaneously perform real-time scanning of distributed field devices.
- Data Highway Plus Networking: Integrates a Data Highway Plus (DH+) interface, supporting the mounting of backup pairs to the plant-level monitoring network. The host computer SCADA system can access these pairs via a single network address or automatic addressing through dual links.
- Underlying Physical Path Switching: Internally designed with a dedicated network switching circuit (Switch Assembly), it directly hard-switches the physical control of the remote I/O bus and DH+ bus to the backup rack when the primary system fails.
- Block-Transfer Control: Fully supports block-transfer commands in the PLC-5 system, allowing configuration control words to be sent online to the 1785-BEM module via logic programs to dynamically adjust the operating parameters of the high-speed serial link.
