RS-232 signal wiring

Wiring

Since the RS-232 interface is not strictly defined, many devices have their own connection methods which may ignore some signal lines or define reserved lines for other functions. It is best to refer to the user’s manual for your device for installation instructions. You may find the following helpful.

In general, DTE (Data Terminal Equipment) refers to the device that is leading the communication. Examples include PC’s, terminals and some printers. DCE refers to the device being communicated with or controlled. Examples include modems, DSU’s (digital service units), printers and lab/factory equipment.

In some situations you may be able to get by with just three lines: data on TXD, a signal ground and a handshaking line. Examples are printer or plotter connections, troubleshooting and situations where you require only one-wire communication.

Terminal or PC (DTE) connections

DB-25 Male: PCL-849		DB-25 Male or Female:
		Terminal
Pin	Signal	Pin	Signal
2	TxD	3	RxD
3	RxD	2	TxD

4	RTS	5	CTS

5	CTS	4	RTS
6	DSR	20	DTR
7	GND	7	GND

20	DTR	6	DSR

8	DCD	8	DCD

Chapter 4 Wiring