Brand:Allen Bradley PLC Item No.:1785-L40B Product Origin:USA Product Dimensions:165 x 51 x 89 mm Product Weight:1.42 kg Payment:T/T, Western Union, Credit Card Goods_stock:15 Shipping Port:Xiamen, China Lead Time:1-3 Days Condition:Brand New And Original Warranty:1 Year Certificate:COO
The Allen-Bradley 1785-L40B PLC-5/40 Processor is a powerful legacy industrial controller designed for complex automation and process control applications. As part of the PLC-5 family, it provides deterministic control and robust communication capabilities for large-scale industrial systems.
It features expanded memory capacity and supports multiple communication channels, including Data Highway Plus (DH+) and Remote I/O, enabling integration across extensive industrial networks. The processor is commonly used in plant-wide control systems where reliability and long-term stability are essential.
Although discontinued, the 1785-L40B remains widely deployed in existing industrial infrastructure, particularly in sectors where system replacement is costly or operational continuity is critical.
Technical Specifications
Parameter
Specification
Product Model
1785-L40B
Product Type
PLC-5/40 Processor Module
System
Allen-Bradley PLC-5 (1771 chassis)
Memory
48K word SRAM
Communication
DH+, Remote I/O, serial
Max I/O Capacity
Up to 2048 I/O (system dependent)
Program Backup
Battery-backed SRAM + EEPROM option
Backplane Load
5V DC (high current PLC-5 architecture)
Mounting Type
1771 chassis slot
Dimensions
165 × 51 × 89 mm
Weight
1.42 kg (3.13 lb)
Industrial Applications
The Allen-Bradley 1785-L40B PLC-5/40 Processor is a high-performance legacy PLC-5 controller used in industrial automation systems for medium to large-scale control applications. It operates within the PLC-5 architecture and is typically installed in 1771 I/O chassis systems.
Typical applications include:
Large-scale manufacturing automation systems
Process control in chemical and petrochemical plants
Power generation plant control systems
Steel and heavy industry automation lines
Water and wastewater treatment systems
Legacy plant-wide distributed control systems
Machine sequencing and interlocking systems
Industrial system upgrades and maintenance projects
Product Advantages
High-capacity PLC-5/40 processor with expanded memory
Supports large distributed I/O architectures
Multiple DH+ and Remote I/O communication channels
Battery-backed SRAM for program retention
EEPROM backup capability for program recovery
Designed for long-life industrial operation
Strong compatibility with legacy Rockwell PLC-5 systems
Stable deterministic control performance
Technical FAQs
1. What is the main function of this module?
It is a PLC-5/40 CPU module used to control industrial automation processes and manage I/O systems.
2. What system does it belong to?
It belongs to the Allen-Bradley PLC-5 platform using 1771 chassis architecture.
3. What kind of applications is it used for?
It is used in large industrial plants requiring reliable, deterministic control and legacy system support.
4. Is it still manufactured?
No, it is a legacy/discontinued product, but still widely used in existing industrial installations.
5. What communication interfaces does it support?
It supports DH+, Remote I/O, and serial communication interfaces depending on configuration.
6. What is its role in a PLC system?
It acts as the central processor managing logic execution and I/O scanning.
7. Does it support large I/O systems?
Yes, it supports large distributed I/O architectures typical of PLC-5 systems.
8. Why is it still used today?
Because many industrial plants still run PLC-5 systems that have not been fully migrated.
9. What is required for operation?
A compatible 1771 I/O chassis, power supply, and I/O modules.
10. Is it suitable for new systems?
No, modern systems typically use ControlLogix or CompactLogix platforms instead.
