node-red-contrib-s2

Node-RED nodes for the S2 energy management protocol (EN 50491-12-2).

S2 is a European standard for demand-side energy flexibility. It defines how a Customer Energy Manager (CEM) communicates with Resource Managers (RMs) to coordinate energy consumption, production, and storage.

Requirements

• Node-RED >= 4.1.0
• Node.js >= 24

Nodes

| Node | Description | |------|-------------| | s2-rm | S2 Resource Manager - manages protocol sessions with one or more CEMs | | s2-rm-config | Configuration for RM identity: resource ID, name, roles, control types, serial number | | s2-cem-config | Configuration for CEM connection (WebSocket URL and credentials) | | s2-websocket | WebSocket transport for S2 communication with a CEM |

Features

• S2 protocol handshake and session management
• Operation Mode Based Control (OMBC)
• Power Envelope Based Control (PEBC) with configurable power constraints
• PowerMeasurement forwarding (3-phase symmetric or per-phase L1/L2/L3)
• PowerForecast support
• Multiple concurrent CEM sessions
• Configurable RM roles (Consumer, Producer, Storage)
• Context variable templates in serial number (e.g. {{global.vrmId}})

Installation

Install via the Node-RED palette manager, or from the command line:

cd ~/.node-red
npm install node-red-contrib-s2

Quick start

1. Add an s2-rm-config node and configure your Resource Manager identity (name, roles, control types).
2. Add an s2-cem-config node with the WebSocket URL and credentials of your CEM.
3. Wire an s2-websocket node to an s2-rm node:
   • s2-websocket output 2 -> s2-rm input
   • s2-rm output 1 -> s2-websocket input
4. s2-rm output 2 carries S2 messages from the CEM (e.g. SelectControlType, ReceptionStatus).
5. s2-rm output 3 carries instructions from the CEM (e.g. PEBC.Instruction, OMBC.Instruction).

Sending PowerMeasurements

To send power measurements to the CEM, inject a message into the s2-rm input:

{
  "payload": {
    "command": "PowerMeasurement",
    "cemId": "cem",
    "values": [
      { "commodity_quantity": "ELECTRIC.POWER.3_PHASE_SYMMETRIC", "value": 1500 }
    ]
  }
}

The s2-rm node emits a PowerMeasurementStart signal on output 1 when the CEM selects a control type, so you can use that to trigger periodic measurements.

Sending PowerForecasts

{
  "payload": {
    "command": "Forecast",
    "cemId": "cem",
    "forecast": {
      "startTime": "2026-04-14T10:00:00Z",
      "elements": [
        {
          "duration": 900000,
          "power_values": [
            { "commodity_quantity": "ELECTRIC.POWER.3_PHASE_SYMMETRIC", "value_expected": 1500 }
          ]
        }
      ]
    }
  }
}

Updating PEBC PowerConstraints

{
  "payload": {
    "command": "PowerConstraints",
    "cemId": "cem",
    "constraints": {
      "commodityQuantity": "ELECTRIC.POWER.3_PHASE_SYMMETRIC",
      "minPower": -3000,
      "maxPower": 3000
    }
  }
}

Constraints are stored at the node level and automatically sent when a CEM selects PEBC.

Development

npm install
npm run build
npm test

License

MIT - Copyright (c) 2026 Victron Energy BV