# Reference — Examples

![code-ref](https://img.shields.io/badge/code--ref-26e92b5-blue)

> [!NOTE]
> Every example flow shipped under `nodes/machineGroupControl/examples/`, plus how to load them, what they show, and the debug recipes that go with them. Live source: `nodes/machineGroupControl/examples/`.

---

## Shipped examples

| File | Tier | What it shows |
|:---|:---:|:---|
| `examples/01-Basic.json` | 1 | One MGC + three `rotatingMachine` pumps driven by inject buttons. A Setup group once-fires `virtualControl` + `cmd.startup` on all three pumps; mode / demand are then driven by buttons. |
| `examples/02-Dashboard.json` | 2 | Same command surface driven by a FlowFuse Dashboard 2.0 page — mode buttons, demand slider, live status rows (mode / total flow / total power / capacity / active machines / BEP %), trend charts, and a raw-output table. |

MGC is not a standalone node — it needs at least one `rotatingMachine` child to dispatch to. Both flows ship three child pumps.

---

## Loading a flow

### Via the editor

1. Open the Node-RED editor at `http://localhost:1880`.
2. Menu → Import.
3. Drag-and-drop the JSON file, or paste its contents.
4. Click Deploy.

### Via the Admin API

```bash
curl -X POST -H 'Content-Type: application/json' \
  --data @nodes/machineGroupControl/examples/01-Basic.json \
  http://localhost:1880/flows
```

---

## Example 01 — Basic standalone

> [!IMPORTANT]
> **Screenshot needed.** Capture of the basic flow in the editor. Save as `wiki/_partial-screenshots/machineGroupControl/01-basic-flow.png`. Replace this callout with the image link.

### Nodes on the tab

| Type | Purpose |
|:---|:---|
| `comment` | Tab header / instructions / driver-group labels |
| `inject` | Setup auto-injects (virtualControl + cmd.startup per pump), mode buttons, demand-by-percent buttons, demand-by-absolute-unit buttons, stop-all button |
| `machineGroupControl` | The unit under test |
| `rotatingMachine` × 3 | Children A / B / C (each with its own simulated pressure pair) |
| `debug` | Port 0 (process), Port 1 (telemetry), Port 2 (registration) per node |

### What to do after deploy

1. Wait ~1.5 s. The Setup group auto-fires `virtualControl` + `cmd.startup` on all three pumps.
2. Click `set.demand = 50` (bare number = percent). MGC selects the best combination via BEP-Gravitation, plans a rendezvous, and dispatches `flowmovement` to the selected pumps.
3. Click `set.demand = 100`. The optimizer probably engages a third pump; the planner schedules its `execsequence(startup)` at tick 0 and delays the running pumps' down-moves so they all hit their new targets together at `t*`.
4. Click `set.mode = priorityControl`. Subsequent demands route through `equalFlowControl` — equal-flow per active pump in priority order. (Planner is bypassed in this mode — see [Limitations](Reference-Limitations).)
5. Click `set.demand = {value: 80, unit: 'm3/h'}` (or use the absolute-unit button). Same path, but the percent-mapping step is skipped — the value lands on the gate as canonical m³/s directly.
6. Click `set.demand = -1`. `turnOffAllMachines` runs: cancels any parked demand, sends `execsequence: 'shutdown'` to every active pump.

> [!IMPORTANT]
> **GIF needed.** Demo of steps 1–6 with the live status panel. Save as `wiki/_partial-gifs/machineGroupControl/01-basic-demo.gif`, target ≤ 1 MB after `gifsicle -O3 --lossy=80`.

---

## Example 02 — Dashboard

> [!IMPORTANT]
> **Screenshots needed.** Two captures from `02-Dashboard.json`:
> 1. The editor tab (left controls column + MGC + 3 pumps + dashboard widget cluster on the right).
> 2. The rendered dashboard at `http://localhost:1880/dashboard/mgc-basic`.
>
> Save as `wiki/_partial-screenshots/machineGroupControl/02-dashboard-editor.png` and `03-dashboard-rendered.png`. Replace this callout with both image links.

### What it adds vs Example 01

| Addition | Why |
|:---|:---|
| FlowFuse `ui-base` + `ui-theme` + `ui-page` setup | One dashboard page hosting four widget groups |
| `ui-button` cluster (Controls) | Mode buttons, `Initialize pumps`, `Stop all` |
| `ui-slider` (Demand) | Drag-to-set demand; passes through the same canonical `set.demand` topic the injects use |
| `ui-text` cluster (Status) | Mode / total flow / total power / capacity / active machines / BEP % rows |
| `ui-chart` × N (Trends) | Flow, power, BEP trends over time |
| `ui-template` (Raw output) | Full key/value table of the latest Port 0 payload |
| Fan-out function | Caches last-known values so delta-only Port 0 updates never blank a status row, and forwards numeric values to charts |

The dashboard buttons fire the **same canonical `msg.topic`** as the inject nodes in Example 01 — there is no separate dashboard command surface to learn.

Required: `@flowfuse/node-red-dashboard` (Dashboard 2.0) installed in the Node-RED instance.

### What to do after deploy

1. Open `http://localhost:1880/dashboard/mgc-basic`.
2. The page auto-initialises the pumps; the `Initialize pumps` button re-runs the setup manually.
3. Drag the **Demand** slider. The Status row's `total flow` and `BEP %` react; the trend charts plot the transition.
4. Switch modes. The mode row in Status reflects the change immediately.
5. Inspect the **Raw output** table for the full Port-0 surface — `headerDiffPa`, `flowCapacityMax`, `machineCountActive`, `relDistFromPeak`, …

> [!IMPORTANT]
> **GIF needed.** Capture clicking through demand 30 % → 80 % → -1 with the trends reacting. 30–45 s is enough.
>
> Save as `wiki/_partial-gifs/machineGroupControl/02-dashboard-demo.gif`. Replace this callout with the image link.

---

## Docker compose snippet

To bring up Node-RED + InfluxDB with EVOLV nodes pre-loaded:

```yaml
# docker-compose.yml (extract)
services:
  nodered:
    build: ./docker/nodered
    ports: ['1880:1880']
    volumes:
      - ./docker/nodered/data:/data/evolv
  influxdb:
    image: influxdb:2.7
    ports: ['8086:8086']
```

Full file: [EVOLV/docker-compose.yml](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/development/docker-compose.yml).

---

## Debug recipes

| Symptom | First thing to check | Where to look |
|:---|:---|:---|
| `mode is not a valid mode` warns every dispatch | `mode.current` is `maintenance` (or a typo). Reset to `optimalControl` or `priorityControl`. | `_runDispatch` switch. |
| `No valid combination found (empty set)` | Demand outside the dynamic envelope, OR every child filtered out (state in `off / coolingdown / stopping / emergencystop` or `auto`-mode rejects the action). | `validPumpCombinations` + state of each child. |
| Group flow stuck at zero after `set.demand` | Pumps never reached an active state — check per-pump startup logs. | Each pump's `state` on its Port 0. |
| Pump warmingup, but then drops back to idle when demand keeps changing | Pre-2026-05-15 race condition: shutdown's for-loop barged through after a residue-handler operational transition. The fix is the `sequenceAbortToken` mechanism in rotatingMachine's FSM. Verify the rotatingMachine submodule is at `394a972` or newer. | rotatingMachine `state/sequenceController.js`. |
| Header pressure not equalising | Pressure children must register with `asset.type='pressure'` and a matching `positionVsParent`. Pure-numeric pressures with no unit are rejected by MeasurementContainer. | `operatingPoint.equalize`. |
| Optimiser picks unexpected combination | Verify `optimization.method` — default is `BEP-Gravitation-Directional`. Per-method scoring lives in `optimizer/`. | `optimizer/{bestCombination, bepGravitation}.js`. |
| Status badge shows `scaling=norm` even after a unit-tagged demand | Badge cosmetic only — the `scaling` field is a legacy artifact and currently always reads `norm`. The dispatch path is unit-self-describing. | `io/output.js` `getStatusBadge`. |
| Per-pump flow / power trends missing | MGC only emits group aggregates on Port 0. Subscribe to each `rotatingMachine`'s Port 0 if you need per-pump series. | `io/output.js` `getOutput`. |

> Never ship `enableLog: 'debug'` in a demo — fills the container log within seconds and obscures real errors.

---

## Related pages

| Page | Why |
|:---|:---|
| [Home](Home) | Intuitive overview |
| [Reference — Contracts](Reference-Contracts) | Topic + config + child filters |
| [Reference — Architecture](Reference-Architecture) | Code map, dispatch lifecycle, planner internals |
| [Reference — Limitations](Reference-Limitations) | Known issues and open questions |
| [EVOLV — Topology Patterns](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topology-Patterns) | Where this node fits in a larger plant |