startup

Sends one message with a fixed payload each time the flow starts.

Properties

• payload type — bool, number, string, or start reason.
• value — the fixed value to send, matching the chosen type. Not used with start reason.

Output

Every message has a reason field saying why the flow started. With payload type start reason, the payload is that same string.

reason	the flow started because
deploy	you clicked Deploy
power_on	the board was powered up
hard_reset	the reset button was pressed
watchdog	a watchdog timer reset the board
deep_sleep	the board woke from deep sleep
soft_reset	software restarted the board, for example machine.reset()
unknown	the board can't tell

Not every board reports every reason. ESP32 boards report the reset button as power_on, because on those chips the button cuts power to the core. A board running a runtime older than 5.1.0 always sends unknown.

Behavior

The flow starts after every Deploy, and again whenever the board resets or powers up with a saved flow. So startup runs even when the editor isn't connected. Use it for setup work, such as setting an output to a known state or drawing a first screen.

It fires once per start and never repeats. For a message you trigger by hand, use inject. For a repeating one, use timer.