node-red-contrib-wow-ethernet-ip 1.0.0

Node-RED nodes for communicating with EtherNet/IP industrial devices (CompactLogix and MicroLogix) using the wow-another-ethernet-ip library. Read, write and monitor PLC tags in real time.

npm install node-red-contrib-wow-ethernet-ip

@keest/node-red-contrib-wow-ethernet-ip

Node-RED nodes for communicating with EtherNet/IP industrial devices — CompactLogix and MicroLogix 1400 (Allen-Bradley / Rockwell Automation).

Built on top of the wow-another-ethernet-ip library.

Features

• Device configuration node — register devices with IP, port, type and a list of tags to poll automatically
• On Change node — observe a tag and emit a message only when its value changes (event-driven)
• Read node — read any tag/address on demand (direct read, no polling cache)
• Write node — write values to any tag/address
• Auto-reconnect — automatic reconnection on connection loss
• Configurable polling interval — set the tag reading cycle (default: 1500 ms)
• CompactLogix buffer tuning — configure read/write cycle times to batch requests and avoid spamming the device
• Supports atomic types (INT, DINT, REAL, etc.), strings (ASCIIString82) and arrays

Installation

Via Node-RED Palette Manager

1. Open Node-RED
2. Go to Menu → Manage palette → Install
3. Search for @keest/node-red-contrib-wow-ethernet-ip
4. Click Install

Via npm (command line)

cd ~/.node-red
npm install @keest/node-red-contrib-wow-ethernet-ip

From local folder (development)

cd ~/.node-red
npm install /path/to/node-red-contrib-wow-ethernet-ip

Restart Node-RED after installing.

Nodes

After installation, three new nodes appear in the EtherNet/IP category on the palette:

🔧 ethip-device (Configuration Node)

A configuration node that manages the connection with a physical device. It is shared between all the other nodes.

Tag address examples:

🔵 ethip onchange

Observes a tag from the device's configured polling list and emits a message only when the value changes.

• No input — this node has no input connector; it fires automatically
• Select the device and pick a tag from the dropdown (populated from the device configuration)
• Perfect for triggering flows on value changes (e.g., save to database when an operator name changes)

Output msg properties:

🟢 ethip read

Performs a direct on-demand read from the device when it receives an input message.

• The tag address can be set in the node config or sent dynamically via msg.address
• The address does not need to be in the polling list — you can read any valid tag
• Each invocation performs a fresh read directly on the device (not from the polling cache)

Input msg properties:

Output msg properties:

🟠 ethip write

Writes a value to a tag/address on the device when it receives an input message.

• The tag address can be set in the node config or sent dynamically via msg.address
• The value to write comes from msg.payload
• For CompactLogix, the library automatically resolves the data type

Input msg properties:

Output msg properties:

Usage Example

Scenario: Monitoring a MicroLogix 1400

Imagine you have a MicroLogix 1400 controlling a furnace. You want to:

1. Monitor the operator name (ST:3) and save it to a database whenever it changes
2. Read the produced quantity (N7:1) on demand
3. Write a reset command to N7:50

Step 1 — Configure the device

Create a device configuration:

• Nome: forno
• Tipo: MicroLogix 1400
• IP: 192.168.1.1
• Porta: 2232
• Tags:
  • N7:1 — quantidade_produzida
  • ST:3 — nome_operador

Step 2 — Monitor operator name changes

1. Drag an ethip onchange node onto the canvas
2. Select device forno, tag nome_operador (ST:3)
3. Connect it to a database node (e.g., MySQL, PostgreSQL)
4. Whenever the operator name changes, the flow triggers automatically

Step 3 — Read produced quantity on demand

1. Drag an ethip read node onto the canvas
2. Select device forno, address N7:1
3. Connect an inject node as input to trigger the read
4. Connect the output to a debug node to see the value

Step 4 — Write a reset command

1. Drag an ethip write node onto the canvas
2. Select device forno, address N7:50
3. Connect an inject node that sends msg.payload = 1
4. When triggered, the value 1 is written to N7:50

Example Flow

An importable example flow is included. In Node-RED, go to Menu → Import and load the file from:

examples/basic-usage.json

Or find it in Menu → Import → Examples → @keest/node-red-contrib-wow-ethernet-ip.

Supported Devices

CompactLogix — Supported Data Types

• Atomic: SINT, INT, DINT, REAL, BOOL
• Struct: ASCIIString82
• Arrays: accessed via TAG_NAME[index]

MicroLogix 1400 — Supported Data Files

• N (Integer)
• ST (String)

Requirements

• Node-RED ≥ 2.0.0
• Node.js ≥ 14.0.0
• Network access to the EtherNet/IP device (TCP port, typically 44818)

License

MIT

Author

Samuel Machado Rodrigues — @keest

Related

• wow-another-ethernet-ip — The underlying EtherNet/IP communication library