Null Modem Cable (DB9F - DB9F) is a cross linked cable. The cable has enough cross-links between the signals to transmit and receive data with accuracy. Moreover, this is used mostly to transfer files from one computer to another.
The null modem cable is ideal to establish connection between ALIX / APU boards, between PCs or between any devices with DB9M (male) connectors..
The cable can transfer data at a maximum 1Mbps speed between two computers.