ITEM TOOLKIT

184 ITEM ToolKit Getting Started Guide
What is a Gate?
A gate is used to describe the relationship between the input and output events in a Fault Tree. For example, a specific
output can occur if and only if specific input events occur. These specific inputs and outputs define each gate. A Fault Tree
can have several different kinds of gates. The gate type defines the appearance of the gate symbol when drawn in the Fault
Tree. In addition, the gate type determines how the inputs to the gate are logically connected for the minimal cut set
analysis process.
Adding a Gate
Fault trees are created by adding gates and events directly into the Fault Tree diagram edit area. As you add gates and
events to a fault tree diagram, the system will automatically position the diagram symbols in the diagram edit area.
Once a new Fault Tree System is added into a Project the TOP gate is automatically created. You can enter and add gates to
the Fault Tree by using the Select and Click method from the Fault Tree Toolbar or by using the Add pull-down menu and
selecting a Gate. You can continue to add gates by simply clicking on any gate.
1. Click on the Fault Tree Tab to open the Fault Tree Canvas (A).
2. Select an OR gate symbol from the Fault Tree Toolbar with the left mouse button (B).
3. Move the mouse cursor to a target gate within the Fault Tree canvas.
4. Once the target gate has been reached, click the left mouse button to add (C).
5. Click on the Select Symbol to stop adding Gates (D).
D
B
C
E
A
F