@signalk/node-red-contrib-signalk

Node-RED nodes for reading from and writing to a Signal K server.

This package is intended for external Node-RED installs that connect to Signal K over WebSocket using @signalk/client.

This cannoat be used in the embedded node-red that runs in the signalk-server via the signalk-node-red plugin.

Install

Search for node-red-contrib-signalk in the node-red Pallete Manager

Signal K Client Config Node

Most nodes use the signalk-client config node.

Config fields:

• Host
• Port
• Use TLS
• Username
• Password

The config node connects and authenticates automatically.

Node Reference

Inputs / Subscriptions

signalk-subscribe (0 in / 1 out)

Subscribe to a Signal K path and emit updates.

Key options:

• path (required)
• context (default vessels.self)
• mode: sendAll, sendChanges, sendChangesIgnore
• flatten: output each path/value as a simple message
• source: optional $source filter
• period: subscription period in ms

When flatten is enabled, output looks like:

{
  "topic": "navigation.speedOverGround",
  "payload": 2.45,
  "source": {
    "label": "actisense",
    "type": "NMEA2000",
    "pgn": 129026,
    "src": "3"
  },
  "context": "vessels.self",
  "$source": "actisense.3",
  "timestamp": "2026-05-14T12:00:00.000Z"
}

signalk-notification (0 in / 1 out)

Subscribe to notification updates and emit messages for matching state/path.

Options:

• notification: a notification path (or leave empty for all)
• state: any, normal, alert, warn, alarm, emergency

Output:

{
  "payload": {
    "path": "notifications.anchor",
    "value": {
      "state": "alarm",
      "method": ["visual", "sound"],
      "message": "Anchor alarm"
    }
  }
}

signalk-geofence (1 in / 3 out)

Checks vessel position against a circular fence.

Outputs:

• Output 1: inside fence
• Output 2: outside fence
• Output 3: either state (inside or outside)

Input can update the fence center/radius:

{
  "payload": {
    "latitude": 60.15,
    "longitude": 24.88,
    "distance": 150
  }
}

If Use My Position is enabled, the fence center tracks vessels.self.navigation.position.

signalk-put-handler (0 in / 1 out)

Handles incoming PUT requests for one path.

Behavior:

• On connect, publishes metadata with supportsPut: true for the configured path.
• Emits PUT requests as Node-RED messages.
• If Use Put Response is disabled, responds immediately with COMPLETED 200.
• If enabled, responds with PENDING 202 and expects a later signalk-put-success or signalk-put-error response.

Output message:

{
  "topic": "electrical.switches.anchorLight.state",
  "payload": true,
  "requestId": "..."
}

Processing Nodes

signalk-flatten-delta (1 in / 1 out)

Flattens a Signal K delta (msg.payload) into one output per path/value.

Output fields include topic, payload, context, $source, and source.

signalk-geofence-switch (1 in / 2 out)

Routes an incoming message by geofence result.

• Output 1: inside fence (passes original message)
• Output 2: outside fence (passes original message)

You can update config at runtime by sending:

• msg.topic = "signalk-config"
• msg.payload = { latitude, longitude, distance }

signalk-delay (1 in / 1 out)

Delays forwarding until the payload has stayed unchanged for delay milliseconds.

Useful for suppressing short transients (for example, startup voltage dips).

Outputs / Writers

signalk-send-pathvalue (1 in / 0 out)

Sends a delta value update.

• Path from configured path or msg.topic
• Value from msg.payload
• Optional configured $source
• Optional configured meta JSON (sent once per path)

Example input:

{
  "topic": "navigation.speedOverGround",
  "payload": 5.3
}

signalk-send-delta (1 in / 0 out)

Sends a fully formed Signal K delta from msg.payload.

signalk-send-notification (1 in / 0 out)

Sends notification deltas.

• Uses node config by default
• If msg.payload is an object, it can override path, state, method, message, and $source
• path is auto-prefixed with notifications. if needed

Example input:

{
  "payload": {
    "path": "notifications.anchor",
    "state": "alarm",
    "method": ["visual", "sound"],
    "message": "Anchor alarm"
  }
}

signalk-send-put (1 in / 2 out)

Sends a Signal K PUT request.

• Path from configured path or msg.topic
• Value from msg.payload
• Context defaults to vessels.self
• Optional configured source

Outputs:

• Output 1: success (COMPLETED 200)
• Output 2: error (non-200 completion)

signalk-put-success (1 in / 0 out)

Responds to a pending PUT request with success.

Expected input:

• msg.requestId (required)
• msg.statusCode (optional, default 200)
• msg.message (optional)

signalk-put-error (1 in / 0 out)

Responds to a pending PUT request with an error.

Expected input:

• msg.requestId (required)
• msg.statusCode (optional, default 500)
• msg.message (optional)

Typical Flow Patterns

Read a single path and only emit changes

1. Add signalk-subscribe.
2. Set path (for example navigation.speedOverGround).
3. Set mode to sendChanges.
4. Connect to debug/function nodes.

Handle remote PUT requests asynchronously

1. Add signalk-put-handler with Use Put Response enabled.
2. Process request in your flow.
3. Send success to signalk-put-success or failure to signalk-put-error using the same requestId.

License

Apache-2.0