The Start trigger block#

Triggers are the entry points of a flow. Every flow opens with one Start block, and you cannot add another. This page covers what Start does and why it is fixed.

Start#

Every new flow has a Start block already on the canvas. The block list does not offer Start, so you cannot place a second one.

The block has no input ports and one Output port that carries any value. When you run the flow, Start fires first and emits the flow's initial input. Connect Start's Output to the input of the first block you want to run.

Why Start is fixed#

Start is the root of the flow. The engine reads the graph out from Start to work out the order in which blocks run. Without Start there is nothing to read out from, and every downstream block becomes orphaned. The canvas keeps Start in place to prevent that.

Trigger the first block#

Most action blocks have a trigger input port, such as Send or Run. Connect Start's Output to that port so the block runs as soon as the flow starts.

Start's Output also carries any initial data. When a Flow block in another flow runs this flow, the value the parent passes in arrives on Start's Output.