1785-BEM/B

Overview of Allen-Bradley 1785-BEM Backup Communication and Expansion Module

The Allen-Bradley 1785-BEM is a backup communication and expansion module designed for the PLC-5 system. It provides high-speed backup communication and automatic switchover for Data Highway Plus (DH+) and Remote I/O (RIO) links, ensuring system reliability in case of processor or communication failures. The module occupies a single I/O slot in the chassis and supports backup of all processor communication channels.

Key Features of Allen-Bradley 1785-BEM

• Backup Capabilities: Provides backup for DH+ and Remote I/O communication channels to enhance system uptime.
• Communication Speed: High-Speed Serial Link (HSSL) communication operating at approximately 1.2 megabaud.
• Module Size: Single slot module designed to fit standard PLC-5 chassis.
• Power Consumption: Requires 0.6 A at 5 V DC from the backplane.
• Connection: Compatible with 1771-WG wiring arm for easy installation and maintenance.
• Output Relay: Includes a customer relay rated at 24 V DC resistive load.
• Operating Environment: Industrial grade designed for reliable operation under typical factory conditions.
• Dimensions: Approximately 4.5 x 12.4 x 6.3 inches (115 x 317 x 160 mm).

Technical Specifications of 1785-BEM

Applications / Use Case of Allen-Bradley 1785-BEM

The 1785-BEM module is critical in PLC-5 systems requiring reliable communication backup to maintain system operation during network disruptions or processor faults. It is widely used in high-availability industrial control environments where downtime must be minimized, supporting seamless transition between primary and secondary communication channels.