Overview
The Allen-Bradley 1785-L86B is a high-performance PLC-5/86 processor module engineered for industrial automation control in 1771 I/O chassis environments. This enhanced programmable controller with protected memory is a high-speed controller installed in a single 1771 I/O chassis slot with an I/O capacity of 3072. The processor leverages protected memory to restrict access to critical program areas, enhancing system security and integrity for control applications requiring multi-user environments with varying privilege levels.
Key Features
- Protected Memory Architecture: Memory protection limits access to critical or proprietary areas of programs and allows selective guarding of processor memory and I/O words.
- 100K Word SRAM: The controller processes I/O information using the 100K words SRAM memory, providing ample program space for complex control logic.
- Multiple Communication Ports: Communicates through the 4 Data Highway Plus/Remote I/O communication ports and supports the Ladder Logic, Sequential, and Structured Text programming languages.
- Extensive I/O Support: The 1785-L86B supports and processes information from the 8-point, 16-point, 32-point, and intelligent 1771 I/O modules.
- Remote Chassis Capability: It can accommodate a total of 93 I/O chassis links with 32 remote chassis per link, and it supports a maximum of 24 I/O racks.
Technical Specifications
- Processor Type: PLC-5/86 (Enhanced with Protected Memory)
- User Memory: 100,000 kilowords SRAM
- Maximum I/O Capacity: 3072 Max Analog I/O
- Communication Ports: 4 × Data Highway Plus/Remote I/O (configurable)
- Backplane Current: 3.3A at 5V DC
- Power Dissipation: 17.3W heat during operation
- Operating Temperature: 0 to 60°C (32 to 140°F) at 5–95% relative humidity without condensation
- Storage Temperature: –40 to 85°C (–40 to 185°F)
- Mechanical Shock: 30G operational shock and 2G vibration at 10–500 Hz frequency
- Module Weight: Approximately 1.42 kg
- Certifications: CSA, UL, C-TICK and CE standards
- Voltage Isolation: 500V for 60 seconds between communication ports and 300V for 60s between ports and relay cartridge
Typical Applications
The 1785-L86B serves demanding control applications including manufacturing lines, process control systems, batch operations, and large-scale machine automation requiring secure access management. Its high I/O capacity and protected memory make it ideal for multi-function plants where different operators need restricted access to specific program logic or data areas. Common deployments include automotive assembly, chemical processing, pharmaceutical manufacturing, and packaging facilities using legacy 1771 I/O infrastructure.
Compatibility & Replacements
The PLC-5-86 uses the 1785-RC relay cartridge for interface with other devices and is compatible with the 1771 memory modules. The Allen-Bradley PLC-5/86 protected processor is equivalent to the Allen-Bradley PLC-5/80 standard processor, respectively, plus the added memory protection feature. For upgrade paths, consult Rockwell Automation documentation or contact our technical team for ControlLogix migration strategies. The module integrates with Rockwell Software programming tools and supports ladder logic, sequential function charts, and structured text programming methods.
