You can access a Component's Fields, Tables, Resources, Controls, Texts and Pages from a containing Form using the components
interface. E.g. components.myComponent.fields.myField.value;
// Get the specific Component
// The Component has the prefix "myPrefix_"
var myComponent = components.myPrefix_myComponent;
// Access a Field from the Component
event.owner.addInfoMessage("The value of myField is " + myComponent.fields.myField.value);