Allen‑Bradley 1785‑L80E Ethernet PLC‑5/80E Processor

Product Introduction

The 1785‑L80E is a feature‑rich Ethernet PLC‑5/80E programmable controller from Allen‑Bradley. It is specifically designed for large‑scale applications with complex control requirements, including discrete and analog control, motion control, calculations, counting, and advanced PID algorithms.

This controller offers 100 Kilowords of user memory for program storage and configuration. Its battery‑backed static RAM, powered by the 1770‑XYC lithium battery, retains data during power loss. For additional non‑volatile backup, you can install EEPROM memory cartridges such as the 1785‑ME16 (16K), ‑ME32 (32K), ‑ME64 (64K), or ‑M100 (100K).

The 1785‑L80E mounts in the left‑most slot of a 1771 I/O chassis and supports up to 93 I/O chassis total, with 32 remote chassis per link. It handles up to 3072 I/O points in any mix, or 3072 inputs plus 3072 outputs in complementary mode, making it suitable for large distributed systems.

Communication Capabilities

The 1785‑L80E stands out with its versatile embedded communication ports, all of which operate independently and simultaneously:

• One 25‑pin RS‑232‑C / RS‑422‑A / RS‑423‑A serial port supporting DF1 Full‑Duplex and Half‑Duplex protocols for point‑to‑point connections.

• One 8‑pin mini‑DIN programming terminal for local access.

• Two combo ports (Channels 1A and 1B) configurable as either Data Highway Plus (DH+) or Remote I/O (RIO) adapter/scanner.

• One dedicated Ethernet port with 10/100 Mbps auto‑negotiation for high‑speed plant‑wide networking.

Furthermore, the Ethernet port enables seamless integration with modern control systems, HMIs, and supervisory software. The DH+ and RIO ports support baud rates of 57.6 Kbps, 115.2 Kbps, and 230.4 Kbps, providing flexibility for legacy and current devices.

Technical Specifications

The 1785‑L80E delivers consistent performance with a program scan time of 0.5 ms per K word for bit logic and 2 ms per K word for typical instructions. Its I/O scan times vary by network type:

• 0.5 ms for extended‑local I/O adapter.

• 10 ms per remote rack at 57.6 Kbps.

• 3 ms per remote rack at 230.4 Kbps.

The controller supports three hardware addressing modes:

• 2‑slot: any mix of 8‑point and 16‑point pair modules.

• 1‑slot: any mix of 8‑ and 16‑point modules; 32‑point modules require I/O pairs.

• ½‑slot: any mix of 8‑, 16‑, and 32‑point modules.

Additionally, the internal clock/calendar maintains time with an accuracy of ±5 minutes per month, and the controller supports up to 65 I/O chassis per link.

Mechanical & Environmental Ratings

Built for rugged industrial use, the 1785‑L80E operates without derating under the following conditions:

• Operating temperature: 0 to 60 °C (32 to 140 °F).

• Non‑operating temperature: ‑40 to 85 °C (‑40 to 185 °F).

• Relative humidity: 5‑95 % (non‑condensing).

• Operational shock: 30G.

• Vibration: 1G at 10‑500 Hz.

The module draws 3.3 A from the 5 V DC backplane and dissipates approximately 65 BTU/hour when operational. It is certified with CE, UL, CSA, and C‑TICK, ensuring compliance with international safety and performance standards.

Installation and Mounting

Installing the 1785‑L80E is simple. Place the module in the left‑most slot of any compatible 1771 chassis (such as ‑A1B, ‑A2B, ‑A3B, or ‑A4B). Ensure the backplane power supply can deliver the required current. For memory backup, insert a 1770‑XYC battery into the dedicated compartment, and optionally install an EEPROM cartridge for non‑volatile storage.

When connecting to Ethernet, use a standard CAT5/6 cable with an RJ‑45 connector. For DH+ or RIO networks, use the combo ports with appropriate cabling. Always verify node addresses and network settings before powering up the system.

Packaging List

Your shipment for the 1785‑L80E includes:

• One 1785‑L80E Ethernet PLC‑5/80E processor module.

• One 1770‑XYC battery (pre‑installed).

• One printed quick‑start installation guide.

• One warranty information card.

Note: Cables, programming software, EEPROM cartridges, and I/O modules are sold separately.
Shipping method: FedEx, UPS, or DHL (carrier selected at checkout).

Frequently Asked Questions (FAQ)

1. What is the key advantage of the 1785‑L80E over other PLC‑5 controllers?
The 1785‑L80E includes a dedicated Ethernet port (10/100 Mbps) for high‑speed networking, in addition to DH+ and RIO combo ports. This makes it ideal for integrating with modern plant‑wide systems while retaining legacy connectivity.

2. Can the 1785‑L80E communicate with both DH+ and RIO devices simultaneously?
Yes. The two combo ports (Channels 1A and 1B) can be independently configured as DH+ or RIO adapter/scanner. Together with the serial and Ethernet ports, all communication interfaces can operate at the same time.

3. What memory backup options does the 1785‑L80E support?
It uses a 1770‑XYC battery for RAM retention. For permanent backup, you can install an EEPROM cartridge like the 1785‑ME64 or 1785‑M100 to store your program without continuous power.

4. How many I/O racks can the 1785‑L80E manage?
It supports up to 93 I/O chassis total, with a maximum of 32 remote chassis per I/O link. This provides ample capacity for large distributed control systems.

5. What software is required to program the 1785‑L80E?
Allen‑Bradley’s RSLogix 5 (version 3.0 or later) is the standard programming package. Use the serial port, DH+, or Ethernet connection to download and debug your program.