MFJ-1270C/1274C COMPUTER INTERFACING
Page 10
If your computer is a IBM or compatible, you should have a serial port with
standard DB-25 or DB-9 pin connector. You may used a standard IBM
serial
modem cable
with the correct gender on each end of the cable.
MFJ Enterprises, Inc. offers optional Starter Pack (MFJ- 1284) for the IBM or
compatible computers. The Starter Pack is supplied with the computer
connecting cable (DB-25 male to DB-25 female) for connecting your MFJ TNC
For other computers with a 25-pin RS-232C port, you should consult your
computer manual or accessory manual to see which pins it uses to send and
receive data on, as well as which pin is used for signal common. Follow the
computer manufacturer's recommendations for connecting the serial port to a
modem. You may also find the technical information in this section useful.
Your MFJ TNC is configured as
D
ata
C
ommunications
E
quipment (DCE), the
technical term for an RS-232C modem. Most computers are configured as
D
ata
T
erminal
E
quipment (DTE). If this is the case for your computer, you will
probably be able to simply wire pin 2 of the MFJ TNC connector to pin 2 of
your computer's RS-232C port, pin 3 to pin 3 and pin 7 to pin 7. You can
provide these connections with a standard 3- wire male-to-female or male-to-
male RS-232C extension cable, depending on whether your computer has a
DB25S or DB25P connector.
If your computer is configured as DCE, you will have to wire pin 2 of your MFJ
TNC to pin 3 of the computer connector, and pin 2 of the computer connector to
pin 3 of your MFJ TNC . Pin 7 of the computer connector will still connect to
pin 7 of your MFJ TNC serial port. Some computers may require that pin 5 of
the computer serial port connector be connected to an appropriate signal. Others
may require connections for pin 8 and pin 20. You can use the computer's
output signals on pins 4 and 6 as shown in Fig. 2-3.
MFJ TNC
RS-232c
Computer
2 2
3 3
7 7
4
5
6
8
