In order to connect two DTEs (computer, terminal, printer etc.) directly using a RS-232 serial cable, a communication method such as a null modem should be utilized. The original RS-232 standard only defined the connection of DTEs with DCEs i.e. modems. With a null modem connection, the transmit and receive lines are crosslinked. Depending on the purpose, sometimes also one or more handshake lines are crosslinked. Several wiring layouts are in use because the null modem connection is not covered by a standard. Null modem adapters converts any straight-through wired cable with connectors into a null modem “cross-wired” configuration, suitable for many serial PC to PC, and PC to printer, applications.