Run Modes: Manual, Automatic, Periodic
Dynamo can run in three modes: Manual, Automatic, and Periodic. This setting is specific to the file, and it is saved with the file.
Automatic: By default, new Dynamo definitions are set to run automatically. This means that the graph is run, or “executed” by the computer, each time there is a change. This has the feeling of running continuously and responsively so that changes you make to the graph at any point cause the appropriate outcome everywhere else.
Manual: Depending on the workflow, you may want to run your Dynamo graph only when you want it to. When you set the run mode to “Manual,” a Run button appears. Your Dynamo graph will only execute when this button is pressed, which means you can make changes without asking the computer to calculate the result until you’re ready. It may seem odd that the output of your graph may not match the input until the graph is run. (If something looks wrong, a little voice should say to you: ”Hit the Run button!”) This run mode is especially useful if your Dynamo graph will start a process that takes some time. For example, if your Dynamo graph places 1,000+ panels in a Revit project, you may want to force Revit to update only when you are ready.
Periodic: Dynamo has the ability to run the graph rhythmically, every x milliseconds, with a frequency you can set. This option is enabled only when a node in the canvas specifically calls for this type of run behavior. Periodic-enabled nodes are those that might inject continually changing information into the Dynamo graph, such as data from a sensor or microcontroller or data from a web service like weather information or stock prices.
Under the hood: Dynamo keeps track of the parts of the graph that must be recalculated each time a change is made, and the next time the graph is run, only the changed parts of the graph and the nodes downstream of those changes are updated. This behavior is especially useful for workflows where large calculations are required; for example, if I use Dynamo to place 1,000 panels in a Revit project, then those panels don’t have to be re-placed each time I update unrelated parts of my Dynamo graph. When your graph is running automatically, the updates happen immediately, but when you run the graph in manual mode, you can get a sneak peak of which parts of the graph will execute. In the Settings menu, check “Show Run Preview”.