State Transition Diagram for an ATM System

uccState Transition Diagram are also known as Dynamic models. As the name suggests, it is a type of diagram that is used to represent different transition (changing) states of a System. It is generally used to graphically represent all possible transition states a system can have and model such systems. It is very essential and important and right for object-oriented modeling from the beginning.

The System consists of various states that are being represented using various symbols in the state transition diagram. You can see the symbols and their description given below :

  1. Initial State –

  2. Final State –

  3. Simple State –



  4. Composite State –


Type of State Description
Initial State In a System, it represents Starting state.
Final State In a System, it represents Ending state.
Simple State In a System, it represents a Simple state with no substructure.
Composite State In a System, it represents a Composite state with two or more parallel or concurrent states out of which only one state will be active at a time and other states will be inactive.

Now let us see the State Transition Diagram of Automated Teller Machine (ATM) System. In this you will see the processing when the customer performs transactions using ATM card.


When the customer inserts the bank or credit card in the ATM’s card reader, the entry action i.e readcard is performed by the ATM machine. If the card is not valid then the machine will perform exit action. After the card is being read successfully, the ATM machine will ask for Pin. Then the customer enters the pin and ATM machine then reads pin. If the pin entered is not valid then machine will perform exit action. If the pin entered is valid, then the machine further process towards transaction. After successful transaction, machine undergoes the exit action i.e., ejectcard that discharges the customer’s card.

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