Wiring; Rs-232 Signal Wiring - Advantech PCI-1602UP User Manual

5.2

Wiring

5.2.1

5.2.1 RS-232 Signal Wiring

Since the RS-232 interface is not strictly defined, many devices have their own con-
nection 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 sig-
nal ground and a handshaking line. Examples are printer or plotter connections, trou-
bleshooting and situations where you require only one-wire communication.
Table 5.18: Terminal or PC (DTE) Connections
Pin
2
3
4
5
6
7
20
8
Table 5.19: Modem Connections
Pin
2
3
4
5
6
7
20
8
PCI/ PCI Express-Communication User Manual
DB-25 Male
Signal
TxD
RxD
RTS
CTS
DSR
GND
DTR
DCD
DB-25 Male
Signal
TxD
RxD
RTS
CTS
DSR
GND
DTR
DCD
DB-25 Male or Female: Terminal
Pin
3
2
5
4
20
7
6
8
Modem (DCE)
Pin
3
2
5
4
20
7
6
8
50
Signal
RxD
TxD
CTS
RTS
DTR
GND
DSR
DCD
Signal
RxD
TxD
CTS
RTS
DTR
GND
DSR
DCD