Product Overview
The Allen-Bradley 1785-L40L is a PLC-5/40L Standard Processor designed for complex industrial automation. With 48K words of user memory and support for up to 2048 analog I/O points, this module coordinates field devices with precision. Its extended local I/O capability makes it ideal for distributed control systems.
Key Features & Benefits
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High I/O Capacity: Supports up to 2048 total I/O (any mix) or 2048 in/2048 out complementary, handling large-scale operations.
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Flexible Memory: 48 kilowords of battery-backed static RAM ensures program retention; optional EEPROM backup via 1785-ME16/-ME32/-ME64/-M100.
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Versatile Networking: Double DH+ or Remote I/O port configurable for adapter or scanner roles, plus one RS-232-C/422-A/423-A port.
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Robust Construction: UL, CE, C-TICK, and CSA certified; operates in 0–60°C environments.
Technical Specifications
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number |
1785-L40L |
| Module Type |
Standard Processor |
| Processor |
PLC-5/40L |
| Max User Memory Words |
48 Kilowords |
| Battery-Backed Static RAM |
Yes |
| EEPROM Backup Option |
Yes (1785-ME16, -ME32, -ME64, -M100) |
| Protected Memory |
No |
| Max Total I/O |
2048 (any mix) or 2048 in + 2048 out (complementary) |
| Max Analog I/O |
2048 |
| I/O Scan Time Per Rack |
0.5 ms (ext. local), 10 ms @57.6 kbits/s, 7 ms @115.2 kbits/s, 3 ms @230.4 mbits/s |
| Max I/O Chassis Total |
61 |
| Max I/O Chassis Extended Local |
16 |
| Max I/O Chassis Universal Remote |
32 per I/O link |
| RS-232-C/422-A/423-A Ports |
1 |
| Control Coprocessor Expansion Port |
Yes |
Industry Applications
The 1785-L40L excels in manufacturing lines, material handling, and process control. For example, in a bottling plant, it coordinates hundreds of sensors and actuators across multiple I/O chassis, ensuring precise filling and capping. Its high analog I/O capacity suits continuous processes like temperature or flow control.
Installation & Setup
Install the 1785-L40L in the leftmost slot of a 1771 I/O chassis. Connect the backplane power supply; the module draws 3.3A at 5V DC. For extended local I/O, use an adapter to link up to 16 additional chassis. Configure communication ports via software for DH+ or Remote I/O operation.
Maintenance & Reliability
Periodically check the battery-backed RAM to ensure program retention. The module dissipates 17W heat; ensure adequate ventilation. Inspect connections and verify scan times remain within specs. Its robust design minimizes downtime, offering long-term cost savings.
Compatibility & Integration
The 1785-L40L works with Bulletin 1771, 1794, 1746, and 1791 I/O modules. It supports 8, 16, and 32-point modules with half/single/double slot addressing. It connects to DH+ and Remote I/O networks, enabling integration with existing Allen-Bradley systems.
Buying Guide
Before purchasing, verify your system's backplane current capacity (3.3A at 5V) and memory requirements. Confirm the need for EEPROM backup modules. PLC Source PRO offers genuine Allen-Bradley 1785-L40L processors with fast shipping and expert support.