Fault Tree Nodes

There are three types of fault tree nodes: Binary Events, Values, and Embedded Modules.

Binary Events

A binary event is an uncertainty with two possible outcomes: true and false. In a fault tree, a binary event represents a particular risk or fault. Each binary event has a probability of occurrence (being true). Binary events appear as green elongated ovals ().


A value in a fault tree stores a number or expression. If this quantity is between zero and one, it can be used to initialize the probability value of a binary event. A value is not an event itself and cannot be connected to a gate. Values appear as blue rounded rectangles ().

Values can also be used to provide cost data for a binary event. A value node that provides either a probability value or cost data to a binary event must be connected to the event.

Expressions entered into a value node's data can use an unlimited number of value node variable names but all value nodes that are referenced in the expression must be connected to the value node.

Embedded Modules

A DPL Fault Tree can have multiple fault tree modules that interact to perform one overall calculation. You can implement this by creating a single node that represents an entire fault tree. This node is called a module. When you incorporate a module into a decision model or another fault tree, it is referred to as embedding a module. There is no limit to either the number of modules you can embed or the number of times you can embed the same module. Embedded modules appears as orange hexagonal nodes. For information on how to embed a module, see Embedding a Module in a Fault Tree.

For information on creating fault tree nodes, see Creating Fault Trees.

Versions: DPL Fault Tree

See Also

Fault Trees Overview

Fault Tree Node Definition



Embedding a Module in Fault Tree

Arranging Fault Tree

Report Node Information to the Log

Copying, Pasting and Duplicating Fault Tree Nodes