Abstract: A tester for characterizing an Ethernet connection is provided. In one example the tester has a connector for coupling to an Ethernet port. The connector has a set of output lines connected to a selector. A controller configures the selector to selectively couple pairs of the output lines to a measurement circuit. Different pairs of output lines are measured to determine which, if any, of the pairs are powered. The tester may also characterize the type of power found. For example, the power may be an “always on” AC or DC power, or provided according to a vendor-specific handshaking sequence. In another example, the power may be compliant with a power standard, such as IEEE802.3af. In characterizing the power according to a particular power implementation, the tester may have to emulate handshaking or other expected responses according to the standard or vendor specification. The tester may also be constructed to characterize the power requirements for a powered Ethernet device.