The EtherNet/IP Edge Router: Connecting Allen-Bradley PLCs Securely

Connecting an Allen-Bradley PLC to the cloud seems daunting, but it doesn't have to be. The key challenge with EtherNet/IP is that it's "tag-based," not register-based like Modbus. This guide explains how a modern industrial edge router with a native EtherNet/IP driver can directly read your PLC tags (from ControlLogix or CompactLogix) and translate them to MQTT—no complex middleware like RSLinx or Kepware required. This edge router approach simplifies PLC data collection and reduces costs.

If your factory floor runs on Rockwell Automation, you know the ecosystem: Allen-Bradley PLCs (like ControlLogix and CompactLogix) are powerful, reliable, and the backbone of your operation. You also know they can feel like a "walled garden."

Getting data out of them isn't as simple as polling a Modbus register. They speak EtherNet/IP (the Common Industrial Protocol, or CIP), a sophisticated, tag-based language. This is where many PLC data collection projects hit a wall, get overly complex, or become incredibly expensive.

As an engineer, I've seen teams spend a small fortune on OPC servers and complex middleware just to get a single data point to the cloud. It doesn't have to be that hard. The secret is to stop thinking of this as a PC software problem and start thinking of it as a hardware solution. The modern industrial edge router is the key.

This is the fundamental hurdle.

• Modbus: (Like we discussed in our Modbus edge router guide) is simple. You ask for data from a numbered address, like 40001.
• EtherNet/IP: This protocol is tag-based. You have to ask for data by its name, like Main_Drive_Speed or Tank_1_Pressure.

This is far more intuitive, but it means your data collector can't be a simple poller. It needs to be an intelligent edge router that can log into the PLC, browse its tag database, and request data by its specific name. A basic edge router can't do this. You need a "smart" edge router that is also a powerful IoT Gateway.

A true industrial edge router (like an EG-series) is also a powerful IoT Gateway. This single device is designed to be the all-in-one solution for allen-bradley plc connectivity.

This "smart" edge router has the native drivers built-in to "speak Rockwell."

This is the "OT" part of the job. The edge router logs into the PLC's tag database just like another HMI or laptop.

1. It Connects: The edge router opens a connection to the PLC's IP address.
2. It Requests: The edge router sends a request: "Hello, 192.168.1.10. Please give me the current value of the tag named 'Motor_Speed_RPM'."
3. It Translates: The PLC responds with the value (e.g., 1750.5). The edge router then takes this data, wraps it in a clean JSON format with a timestamp, and publishes it to the cloud via MQTT.

Your cloud platform never needs to know what EtherNet/IP or "CIP" is. It just receives clean, usable data. This is the core ethernet/ip edge router function.

This is the "IT" part. While the edge router is translating data, it's also being your secure border checkpoint.

• It Isolates: The secure edge router creates a small, firewalled network for the PLC, isolating it from the general corporate IT network. This is a critical ot security function.
• It Connects Securely: The cellular edge router (like the EG5120 ) uses a 4G/5G connection to bypass the IT network entirely, creating a true "air gap" for your data.
• It Encrypts: It sends all MQTT data out over a secure, encrypted VPN tunnel.

This is the real business case. For years, the "official" way to connect Allen-Bradley PLCs was to buy a powerful PC, install Windows Server, and buy an expensive middleware license from vendors like Kepware (KepServerEX) or even Rockwell itself (RSLinx).

This server would sit on the factory floor, talk to the PLCs, and then (maybe) talk to the cloud. A modern industrial edge router makes this entire stack obsolete.

Let's be brutally honest about the TCO of the "old way":

• PC Hardware: $1,000
• Windows Server License: $1,000
• OPC/Middleware License: $2,000 - $5,000
• Maintenance: (Windows Updates, patches, fan failures, etc.)
• Total: $4,000 - $7,000+... just to get data from one line.

The "new way" is a single, solid-state, industrial edge router that costs a fraction of that, has no moving parts, and requires no Windows patching. The edge router tco comparison is a no-brainer. This edge router is the clear winner.

This is the ROI superpower that closes the deal. The sameindustrial edge router that's collecting your data also connects to Add One Product: RCMS (Robustel Cloud Manager Service).

• The Problem: Your Allen-Bradley machine in another state is down. You have to fly an engineer out ($5,000 cost) with their laptop running Studio 5000.
• The Edge Router Solution: Your engineer opens their laptop, logs into RCMS, and activates RobustVPN.
• The Result: They are now securely "tunneled"through the edge router and can remotely access the CompactLogix or ControlLogix PLC with their Studio 5000 software (and RSLinx).
• The Payoff: You just saved $5,000 and fixed the machine in 30 minutes. This edge router just paid for itself 10 times over. It's an edge routerand a plc remote access gateway in one.

Stop thinking Allen-Bradley data is "locked up" or requires a massive, expensive software project. It's not. The EtherNet/IP protocol is powerful, and with the right tool, it's easy to access.

A modern industrial edge router is that tool. It's a single, rugged device that securely reads EtherNet/IP tags natively, translates them to MQTT for the cloud, and can even provide secure remote access for your engineers—all without a single PC or middleware license. This edge router solution is simpler, cheaper, more secure, and more reliable.