US Patent 7574318 I/O port tester

An I/O port tester includes a first relay, a second relay, a first resistor, a second resistor, a plurality of serial plugs, a water sensor plug, a direct current (DC) voltage plug, and two data plugs. A half of the serial plugs is correspondingly connected to the other half of the serial plugs. The DC voltage plug is connected to the water sensor plug via a switch of the first relay and the first resistor, and connected to the water sensor plug via a switch of the second relay and the second resistor. The first and second resistors respectively simulate two different working conditions. The data plugs are respectively connected to an inductance coil of the first relay, and an inductance coil of the second relay.