Allen-Bradley 1785-L20E Ethernet PLC-5 Programmable Controller

The 1785-L20E is an industrial-grade Ethernet PLC-5 programmable controller designed by Allen-Bradley for control and automation across specialized industrial environments. Operating as an open-type modular component within the 1771 I/O architecture, this processor features 16 Kilowords of maximum user memory and an integrated battery-backed static RAM to preserve active program data. The module provides multi-protocol network communication interfaces, including an embedded RJ45 Ethernet port supporting high-speed data transmission, email client functionality, and integration with machinery supervisory networks. It functions effectively as a control system component to manage field inputs and outputs while reducing downtime in large-scale manufacturing and processing operations.

Features

• Equipped with 16 Kilowords of maximum user memory words and battery-backed static RAM for volatile memory preservation.
• Support for dynamic or static network IP assignment via BOOTP, DHCP, or manual configuration.
• Integrated email client functionality capable of transmitting standard SMTP protocol messages triggered by internal program instructions.
• Configurable auto-negotiation settings supporting data transmission rates of 10/100 Mbps in full-duplex or half-duplex operating modes.
• Features an embedded HTTP web server and Simple Network Management Protocol (SNMP) functions that can be enabled or disabled via configuration software.
• Removable memory backup extension option utilizing 1785-ME16, -ME32, -ME64, or -M100 EEPROM modules.

Applications

• Distributed automated processing systems across oil and gas refinement utilities.
• High-speed assembly line sequence automation and production machinery.
• Water treatment plants and chemical processing multi-chassis control configurations.
• Power generation station subsystem handling and sequence-of-events reporting.

Technical Specifications

Connections/Interfaces

Installation Guidelines

• Always mount the module within a protective enclosure that requires a dedicated tool for access, ensuring the local atmosphere meets Pollution Degree 2 conditions.
• Set the unique DH+ Station Address for Channel 1A using the rear-panel switch assembly SW-1 before inserting the unit into the chassis slot.
• Prevent internal hardware damage from electrostatic discharge by wearing an approved grounding wrist strap and avoiding physical contact with connection pins or circuit components.
• Limit adjacent slot thermal loading by confirming that adjacent hardware slot power dissipation remains below a maximum limit of 10 W.
• Isolate communication lines from high-voltage cables, routing signal wiring through dedicated instrument trays to minimize the risk of electromagnetic noise coupling.
• If changing the operational settings for the embedded HTTP web server or SNMP client while online, a complete system power cycle must be performed for adjustments to take effect.

Compliance and Certifications

• IEC/CISPR Publication 11 (Group 1, Class A Industrial Equipment) 
• Class I Division 2 Groups A, B, C, D Hazardous Locations (North American Hazardous Location Approval)