Null modem adapters are used to connect two DTEs (computer, terminal, printer etc.) directly using a RS- 232 serial cable. The original RS-232 standard only defined the connection of DTEs with DCEs (i.e. modems). With a null modem adapter, the transmit and receive lines are cross-linked. Depending on the purpose, one or more handshake lines are cross-linked. Several wiring layouts are in use because the null modem connection is not covered by a standard. B&B Electronics’ Null Modem adapters come with a variety of connector options and pin-outs to cover most common applications.
NULL MODEM ADAPTER, DB9 MALE MALE