In this System Configuration:

• Pin 3 (GPIO02) of the Raspberry Pi 2 GPIO header is configured as an output using an instance of the DO_PI type.
• Pin 5 (GPIO03) is configured as an input using an instance of the DI_PI type.
• The output on pin 3 is connected to the input on pin 5 via a jumper wire for loopback testing.
• Upon launching the system configuration, the following test window is opened:
  
• Clicking on the OUTPUT check box causes the OUTPUT.OUT value to flip; this value is passed to the PIN3.X input.
• An event is passed from OUTPUT.IND to PIN3.REQ; this causes the flipped value at PIN3.X to be written to pin 3 of the Raspberry Pi 2 GPIO header.
• The output state is passed electrically from pin 3 to pin 5 of the GPIO header.
• An event is passed from PIN3.CNF to PIN5.REQ, which causes the value of the input at pin 5 of the header to appear at PIN5.X, which is passed to INPUT.IN.
• An event is passed from PIN5.CNF to INPUT.REQ, which causes the INPUT display to be updated with the new value of PIN5.IN.