Overview
The Allen-Bradley 1785-LT2 is a PLC-5/25 processor from the established PLC-5 family of programmable logic controllers. This processor delivers reliable performance for medium-to-large scale industrial automation applications requiring substantial memory and I/O capacity. The 1785-LT2 is engineered for robust control of complex processes and is widely used in legacy manufacturing systems where continuity and proven uptime are critical.
Key Features
- Memory: 13K words of user memory, expandable to 17K or 21K words
- I/O Capacity: Supports up to 1024 total digital and analog I/O points
- Communication Ports: One DH+ (Data Highway Plus) channel and one Remote I/O channel for network integration
- Compatibility: Uses same programming software and instructions across PLC-5 processor family; ladder programs and SFCs compatible
- Robust Design: Proven performance in industrial environments with reliable signal processing and I/O scan capabilities
Technical Specifications
- Part Number: 1785-LT2
- Series: A (SER A)
- Processor Type: PLC-5/25
- User Memory: 13K words (expandable to 17K or 21K)
- Memory Type: SRAM
- Maximum I/O: 1024 total points (digital and analog)
- Analog I/O Support: 1024 analog I/O capable
- DH+ Channels: 1
- Remote I/O Channels: 1
- Operating Temperature: 0 to 60°C (32 to 140°F)
- Storage Temperature: -40 to 85°C (-40 to 185°F)
- Humidity Range: 5 to 95% (non-condensing)
- Weight: 1.370 kg (approx.)
- Certifications: Class 1 Division 2, Groups A, B, C, D, T5
- Backplane Power Requirement: 2.5A @ 5VDC
Typical Applications
The 1785-LT2 excels in large-scale automation environments including food and beverage processing, pharmaceutical manufacturing, automotive assembly lines, chemical processing, packaging systems, and metal fabrication. Its high I/O capacity and expandable memory make it suitable for systems controlling hundreds of sensors, motors, and discrete devices simultaneously. The DH+ and Remote I/O communication options enable integration with remote facilities and distributed control architectures.
Compatibility & Replacements
The Allen-Bradley 1785-LT2 is part of the classic PLC-5 processor family and shares the same physical dimensions, programming platform, and instruction set as other PLC-5 models (1785-L2, 1785-L3, 1785-L4, 1785-L8). Ladder programs written for the 1785-LT2 are compatible with other processors in the family, simplifying system standardization. The module uses the leftmost slot in 1771 I/O chassis and requires the 1785-BCM (Battery/Backup Module) for multi-processor configurations. Note: The 1785-LT2 does not support removal and insertion under power; ensure power is disconnected before servicing.
