Epson 4100 manual DTE Device DCE Device Pin # Signal Abbreviation, Common RS-232-C

B-4	Appendix B—Serial Interface
DTE Device					DCE Device
Pin #		Signal	Abbreviation		Pin #
1		Frame Ground	FG		1
2	%	Transmitted Data	TxD	%	2
3	&	Received Data	RxD	&	3
4	%	Request To Send	RTS	%	4
5	&	Clear To Send	CTS	&	5
6	&	Data Set Ready	DSR	&	6
7		Signal Ground	SG		7
8	&	Data Carrier Detect	DCD	&	8
20	%	Data Terminal Ready	DTR	%	20

Common RS-232-C

Note that two signal names in this group, Transmitted Data and Received Data, are defined from the perspective of the DTE device. The same terms are used, however, for DCE devices. For DTE devices, the Transmitted Data signal is assigned to Pin 2 and is a data output; for DCE devices, the Transmitted Data signal is also assigned to Pin 2, but is a data input.

To avoid confusion, note that Transmitted Data and Received Data are misleading terms when used to describe DCE signals. The following chart defines these and the other nine common RS-232-C signals in relationship to DTE and DCE devices.