node-red-contrib-signalbox

A Node-RED node that does nothing to your messages - it passes them through completely unchanged - but watches the traffic going past, the way a signalman in a signal box logs every train that passes their section of track. No configuration is required to use it.

Install

From your Node-RED user directory (typically ~/.node-red):

npm install node-red-contrib-signalbox

Or use the Manage Palette command in the Node-RED editor.

Usage

Wire it into any point in a flow - one input, one output, message unchanged. Optionally give it a Name to identify it within its group's combined stats, and a Group (see below) to combine its numbers with other signalboxes.

Status badge

Updates continuously (not just when messages arrive), e.g.:

3s ago · 12/hr · 340/day

By default the dot also changes color as things get stale:

| Color | Meaning | |--------|---------| | Green | Fresher than Warn after | | Yellow | Between Warn after and Error after | | Red | Older than Error after |

Untick Change status color as it gets stale for a neutral blue dot with text only.

Node context

Each instance writes a snapshot to its own node context under the key signalbox:

{
  id: "<node id>",
  name: "front-door-sensor",
  lastSeen: 1737000000000,
  counts: { hour: 12, day: 340, week: 2100, total: 58211 },
  avgIntervalMs: 4213,
  topPayloads: [ { value: "\"open\"", count: 88 }, ... ],
  topPayloadsSince: 1736913600000,
  updated: 1737000005000
}

Grouping and combined global stats

Every signalbox with the same Group combines into one shared aggregate under global['signalbox-<group>'] - or global.signalbox if Group is left blank. This is the combined view across every member, not a separate entry per node:

{
  counts: { hour: 40, day: 1180, week: 7350, total: 210044 },  // summed across the group
  busiest: { id: "<node id>", name: "back yard camera", dayCount: 640 },
  topPayloads: [ { value: "\"motion\"", count: 820 }, ... ],   // merged across the group
  members: {
    "<node id 1>": { name: "front door camera", counts: {...}, ... },
    "<node id 2>": { name: "back yard camera", counts: {...}, ... }
  },
  updated: 1737000005000
}

From a Function node:

const cameras = global.get("signalbox-cameras");
console.log(cameras.busiest, cameras.counts.day, cameras.topPayloads);

Members that stop reporting (deleted, or moved to a different group) drop out of the aggregate automatically after 5 minutes of silence, so removed nodes don't permanently inflate the group's totals.

Top payload tracking

Tracks the top 10 most frequent payload values seen, using a tally that resets on the Reset tally every interval (default: daily) rather than a true sliding window, and is capped at 500 distinct values (least frequent evicted first) to bound memory. Works best for payloads with a naturally small set of repeating values (status strings, event names, error codes) rather than continuously-varying data like raw sensor readings. Untick Track top 10 payloads by frequency to disable this entirely.

Update interval

Update every controls how often the status badge refreshes and how often snapshots are written to context/global.signalbox - it has no effect on message flow itself, and is decoupled from message rate so a high-throughput flow won't write to context on every single message. Defaults to 5 seconds.

A note on persistent context stores

If you've configured a persistent (non-memory) context store as your default, each signalbox writes into it on every Update every tick. With many instances, or a slow store, consider increasing the interval.

License

Apache-2.0