An emitter has only an outlet, so it always starts a branch. Pick how often it samples — anywhere from every second to every five minutes — and wire the payload into a Condition for a threshold alert, a Time Series for a live chart, or an AI Prompt for a read on what's happening.
A flow whose only sources are emitters is silent until you press ▶ on the canvas. It is never started by the Enabled toggle or by launching the app, and the stream stops when you press ■ or quit — this is the one kind of flow that does not survive a relaunch on its own.