Classic RS232 Connections

When connecting two serial devices, different cable types must be used, depending on the characteristics of the serial device and the type of communication used.

Overview of RS232 SUB D9 (D-Sub DB9) interconnections

serial device 1	serial device 2	flow control (handshaking)	recommended cable
DTE (Data Terminal Equipment)	DTE	no handshake signals	simple null modem cable
DTE	DTE	DTE/DCE compatible hardware flow control	null modem cable with partial handshaking
	DCE (Data Communications Equipment)	no handshake signals	simple straight cable
DTE	DCE	hardware flow control	full straight cable
DCE	DCE	no handshake signals	simple null modem cable, but with SUB D9 male connectors on both ends
DCE	DCE	hardware flow control	null modem cable with partial handshaking but with SUB D9 male connectors on both ends

NOTE: A great alternative to make the correct interconnection between various DTE and DCE type devices is to use the Yost Serial Device Wiring Standard approach by Dave Yost.

SUB D9 Simple Straight Cable

Area of Application: DTE-DCE Communication where no additional handshake signals are used.

DL-3LineCable

SUB D9 Full Straight Cable

Area of Application: DTE-DCE Communication with hardware flow control using additional handshake signals.

DL-1-1_CableFullyAssigned

SUB D9 Simple Null Modem Cable without Handshaking

Area of Application: DTE-DTE Communication where no additional handshake signals are used.

DL-SimpleNullModemCable

SUB D9 Null Modem Cable with Full Handshaking

Area of Application: DTE-DTE Communication with DTE/DCE compatible hardware flow control. Works also when no handshake signals are used.

DL-FullNullmodemCable