1785-L20E/E

Overview

The 1785-L20E/E is a PLC-5/20E Ethernet processor module from Allen-Bradley, built for medium-scale automation tasks. It offers reliable communication through multiple embedded interfaces and supports a wide range of remote I/O configurations.

Processor & Memory

• Processor Type: PLC-5/20E

• Max User Memory: 16K words

• Battery-Backed RAM: Yes (Battery: 1770-XYC)

• EEPROM Backup Support: Yes (1785-ME16/-ME32/-ME64/-M100 compatible)

• Protected Memory: Not supported

I/O Capability

• Max Total I/O: 512 (any mix) or 512 in + 512 out (complementary)

• Max Analog I/O: 512

• Max I/O Racks: 4 (Rack 0–3)

• Remote I/O Chassis Supported: 12

• Max Universal Remote I/O Chassis: 12

• Max I/O Chassis (Total): 13

• Extended Local Chassis: 0

Communication Interfaces

• Embedded Ports:
  • 1 Ethernet
  • 1 DH+ (Fixed)
  • 1 DH+/Remote I/O (Adapter or Scanner)
  • 1 serial port (RS-232, RS-423, RS-422A selectable)

• Coprocessor Expansion Port: Supported

Performance & Electrical

• I/O Scan Time per Rack:
  • 10 ms at 57.6 kbps
  • 7 ms at 115.2 kbps
  • 3 ms at 230.4 kbps

• Backplane Current Load: 2.3 A

• Power Dissipation: 12 W

• Power Supply Compatibility: 1771-P4S, -P6S, -P4S1, -P6S1

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