MQTT

ActionsFrom Trader

• Trigger
• Message

MQTT

broker.example.com · bellchain/alerts · at most every 4 h

This is how the node looks on the board: inputs on the left. As an action it sits at the end of the chain.

Like a slot in a sorting rack: Bellchain drops each alert into a topic’s slot on your broker, and every device subscribed to it picks it up, such as Home Assistant or Node-RED.

Alert to a topic on your MQTT broker. Sends every alert as a message to a topic on your own MQTT broker, for example for Home Assistant, Node-RED or a dashboard. The broker must be reachable from the internet, encrypted and with a valid certificate. The message is the same JSON as with the webhook. MQTT comes with the Trader plan and up. Example: on “Price below 80,000”, Home Assistant turns the office light red.

What it looks like

• signal true
• alert goes out
• held back
• cooldown running

The alert comes when the trigger switches from false to true. If it stays true, no second one comes. If it switches again during the cooldown, Bellchain holds the alert back (circle); the replay counts such cases as “held back by the cooldown”.

Settings

The settings appear on the right under “Properties” once you click the node on the board. Below each field you find the same explanation as here.

Broker

Default: empty · any text, at most 300 characters, must be filled in before activating

Address of your broker with mqtts:// (TLS, usually port 8883) or wss:// (WebSocket over TLS, usually port 443 or 8884, often ending in /mqtt). Unencrypted (mqtt://) and addresses on your own network do not work.

Topic

Default: bellchain/alerts · any text, at most 200 characters, must be filled in before activating

The topic every alert goes to, such as bellchain/alerts. Without + and #, those exist only for subscribing.

Username

Default: empty · any text, at most 200 characters

Username for the broker; leave empty if it needs none.

Password

Default: empty · any text, at most 500 characters, empty when you export a chain

Password for the broker. Ideally create a user of its own that may only write to this topic. It stays empty when you export the chain.

Delivery

Default: Confirmed (QoS 1) · under “More”

QoS 1: the broker confirms each message, otherwise Bellchain tries again. QoS 0: without confirmation.

• Confirmed (QoS 1) (default): Without a confirmation, Bellchain sends again.
• Unconfirmed (QoS 0): Send once without waiting for the broker.

Keep last alert

Default: Do not keep · under “More”

With “Keep” (retain) the broker stores the last alert; whoever subscribes to the topic anew gets it at once, such as a dashboard after a restart.

• Do not keep (default): Only current subscribers get the alert.
• Keep: The broker keeps the last alert for new subscribers.

Content

Default: JSON as with the webhook · under “More”

JSON with chain, pair, price, values and message, as with the webhook, or just the message text, for example for a display.

• JSON as with the webhook (default): All data of the alert for further processing.
• Message only: The message text without highlighting.

At most every … hours

Default: 4 h · from 0 to 168 h

Cooldown: after an alert the action waits at least this long before the next one. 4 hours suit most chains. 0 means an alert every time the condition turns true.

Message

Default: {{chain}}: {{values}} · any text, at most 1,000 characters, multi-line

The alert text. {{chain}} inserts the chain’s name, {{values}} the values of the nodes, {{price}} the price; there are also {{pair}}, {{coin}} and {{time}}. Use **bold**, _italic_ and `code` to highlight text. If a message template is connected to the Message input, its text is used instead.

Example

Sends the alert as JSON to the topic on your MQTT broker, for example for Home Assistant (Trader plan).

How to connect the nodes:

1. Candle (Price) → RSI (Value)
2. RSI (RSI) → Compare (Value)
3. Compare (true/false) → MQTT (Trigger)

On the board it reads: broker.example.com · bellchain/alerts · at most every 4 h

Chain as JSON

To try it, copy it and paste it in the editor under “Import”. Importing creates a new chain.

mqtt.json

{
  "name": "Example: MQTT",
  "version": 1,
  "nodes": [
    { "id": "c1", "type": "core.candle", "position": { "x": 40, "y": 40 }, "settings": { "pair": "BTC/USDT", "timeframe": "1h" } },
    { "id": "r1", "type": "core.rsi", "position": { "x": 260, "y": 40 }, "settings": { "length": 14 } },
    { "id": "k1", "type": "core.compare", "position": { "x": 480, "y": 40 }, "settings": { "operator": "below", "value": 30 } },
    { "id": "q1", "type": "core.mqtt", "position": { "x": 700, "y": 40 }, "settings": { "url": "mqtts://broker.example.com:8883", "topic": "bellchain/alerts", "username": "bellchain" } }
  ],
  "edges": [
    { "from": "c1.close", "to": "r1.in" },
    { "from": "r1.out", "to": "k1.in" },
    { "from": "k1.out", "to": "q1.in" }
  ]
}

Inputs and outputs

Only matching types connect: number series to number series (round pin), signal to signal (square), message to message (diamond).

Direction	Pin	Type	Note
Input	Trigger	Signal (true/false)	required
Input	Message	Message	optional
Output	–	–	No outputs.

Good to know

• Search also finds it under: notification, message, alert, mqtt, broker, home assistant, node-red, iot.

Technical details

MQTT 3.1.1 over TLS (mqtts://) or WebSocket over TLS (wss://): per alert connect, publish with QoS 0 or 1, disconnect. Client ID bellchain-…, clean session. The delivery log keeps host, port and topic, never the password.

• Type in the chain: core.mqtt · Version 1.0.0 · Category key act
• Settings in the chain: url (Broker), topic (Topic), username (Username), password (Password), qos (Delivery), retain (Keep last alert), format (Content), cooldown (At most every … hours), message (Message)
• Pins in the chain: Input in, message
• Effect: notifies via MQTT
• How a node is built