Null Modem-0812 page 1/1
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MFNM25, MMNM25, MF23R25, MFDTE25, MMNM9
RS-232 Null Modem Adapters
Interconnect two devices with similar ports
Reverse Pin 2 (TD) and Pin 3 (RD)
Multiple Pin Arrangements
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.
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