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21–1
Chapter 21
ZyXEL MODEMS AND A PC
All of the modems of the 2864 series may be used with a PC. If you install the in-
ternal PC card model, you don't need a serial cable. The modem's standard profiles
should be just fine with most applications. If you are connecting to the modem’s
parallel port, make sure that you have a bidirectional PC parallel port and use a
25-wire cable to make the connection. The ZyXEL serial/parallel adapter card pro-
vides you with a special high-speed PC-modem communication advantage when
working with a 2864 series modem.
Serial Cable
Most PCs are equipped with more than one serial port. Standard cables are readily
available from many suppliers. Usually, serial ports are manufactured in two forms,
either with a 25-pin male jack or a 9-pin male jack.
To connect a PC to the modem, you need the following 9-wire cable:
Computer
Signal Modem
9-pin 25-pin
18CD 8
2 3 RXD 3
3 2 TXD 2
4 20 DTR 20
5 7 Signal Ground 7
6 6 DSR 6
74RTS 4
8 5 CTS 5
922RI 22
12345
6789
1 2 3 4 5 6 7 8 9 10 11 12 13
14 15 16 17 18 19 20 21 22 23 24 25
Fig. 21.1: 25-pin and 9-pin male connectors usually found in PCs.