Allen-Bradley 1785-L30B Controller Module

Technical Specifications

Key Operational Characteristics

• Versatile Communication Ports: The unit features two universal channels that users can configure for either Data Highway Plus (DH+) or Remote I/O (RIO) scanner/adapter modes. This flexibility allows the processor to act as a master controller for field devices or as a peer on a plant-wide data network.
• Comprehensive I/O Support: The 1785-L30B manages up to 1024 discrete I/O points. Because it supports up to 28 remote racks, maintenance teams can implement distributed control architectures that reduce field wiring costs over large physical areas.
• Integrated Memory Protection: An internal lithium battery safeguards the volatile RAM during power outages. Consequently, the controller retains its operating system, user programs, and variable data for nearly three months without external power, preventing costly data loss.
• Standardized Serial Connectivity: The dedicated serial port supports multiple electrical standards, including RS-232 and RS-422A. This allows the controller to communicate directly with peripheral devices like barcode scanners, HMIs, or industrial printers using DF1 protocol.
• Manual Control and Diagnostics: The front panel incorporates a physical three-position keyswitch for selecting between Run, Program, and Remote modes. Furthermore, a suite of diagnostic LEDs—including PROC, BATT, and FORCE—provides immediate visual feedback regarding the operational health and I/O status of the system.

The Allen-Bradley 1785-L30B serves as a high-performance central processing unit within the classic PLC-5 platform. This “Enhanced” processor delivers robust control logic capabilities for industrial automation systems that require substantial I/O density and diverse communication options. With a user memory capacity of 32,000 words, the module effectively manages complex ladder logic programs and extensive data tables.