ControlNet PLC-5/20C Processor 1785-L20C Allen-Bradley

Product Overview

The Allen-Bradley 1785-L20C is a ControlNet PLC-5/20C processor module. It provides 16K words of user memory, supports up to 512 I/O points and integrates dual-media ControlNet with DH+ and remote I/O capabilities for distributed control architectures.

Technical Specs

• Processor: PLC-5/20C ControlNet
• User memory: 16K words
• Max I/O: 512 any mix (or 512 in + 512 out complementary)
• Max analog I/O: 512
• Networks: Dual-media ControlNet, DH+, Remote I/O (adapter/scanner)
• Serial port: RS-232-C / 422-A / 423-A
• Max I/O chassis: 13 total (12 universal remote)
• Typical scan time: 2 ms/Kword
• Battery: 1770-XYC lithium

Key Features

• Native ControlNet connectivity for high-speed deterministic I/O
• Supports complementary I/O and multiple communication ports
• Battery-backed memory with EEPROM backup option
• Compatible with standard 1771 chassis

FAQ

• Memory size? 16K words.
• Max I/O? 512 points.
• Network? ControlNet (dual media) + DH+/RIO.

Installation Guide

1. Install the processor in the leftmost slot of a 1771 I/O chassis.
2. Connect ControlNet media with proper terminators.
3. Install the battery and set backplane switches as required.
4. Configure the processor and I/O in RSLogix 5.
5. Download the program and verify ControlNet and I/O status.

Selection Tips

• Choose for medium-sized ControlNet PLC-5 applications.
• Pair with 1785-ME series EEPROM for program backup.
• Confirm ControlNet cable and node addressing requirements.