2400 BPS Pocket FaxModem  (250-3105)                   Faxback Doc. # 5769

Connecting The FaxModem To The CPU

This section explains the procedure for connecting the faxmodem to the
phone line, the power, the computer or other serial device and, if
desired, a telephone.

Once the faxmodem is connected it must be configured.  Configuration is
covered in the next chapter, "Getting Ready to Communicate".

The diagram below shows the faxmodem connected using a serial cable, which
is the recommended configuration.  Although the faxmodem can be plugged in
directly to a computer that has a 25-pin serial port, it is recommended
that you use a serial cable.  Using a cable will prevent the physical
damage to the faxmodem or the computer's serial connector that could
result if the faxmodem were bumped too severely while connected directly.

                       ┌────────────────┐      ┌─┐
                  ┌────┤    FaxModem    │      │ │
                  │    └────────┬┬┬─────┘      ├─┤Power Connection
     ┌──────────┐ │             ││└────┐       │█│
     │          │ │             │└───┐ │       └█┘
     │ Computer │ │             └──┐ │ └────────┘
     │Connection├─┘                │ │
     │          │                  │ └──────┐
     └──────────┘                  │        │    ┌──┐
                              ┌────┴─────┐  └────┤  │
                              │Telephone │       │  │
                              │Connection│       └──┘
                              │(Optional)│        Telephone
                              └──────────┘        Line Connection

The Serial Connector

To connect the faxmodem to your computer, the computer must have an unused
serial port, also known as an RS-232 interface.  The jack that you plug
this serial connection into comes in several different shapes, but the
most common by far is the DB-25 connector, followed by the "DB-9" on older
Macintosh computers, and the "Circular 8" on the Mac Plus and the Mac SE.

On computers with plug-in expansion slots like the IBM PC and compatibles,
the serial port is normally part of an expansion card, and therefore can
be found at the expansion card slot openings at the back of the PC. Many
other machines, particularly those without expansion slots (including
laptops and other portables), have the serial port built-in.  Either way,
it will normally be labelled "serial port" or "RS-232C".

The Serial Cable

If you are using a cable to connect the faxmodem to your computer (which
is the recommended configuration), read the following discussion about
cables.  Otherwise, you can skip ahead to "The Phone Line and Telephone
Connections".  External faxmodems normally do not come with serial cables,
since each computer requires a different cable depending on the type of
serial connector it uses and how that connector is wired.

Since the serial port of this faxmodem is compatible with the Hayes 2400
external modem, the easiest way to specify the correct cable to your
computer dealer is by asking for the cable to connect a Hayes 2400 bps
modem to your brand and model of computer.

If you are using a Macintosh computer, see Appendix C for information
about the correct cable to use.

More About Serial Cables

There are two types of serial configuration: Data Communication Equipment
(commonly known by the initials (DCE) and Data Terminal Equipment
(commonly known by the initials (DTE).  The serial port of this faxmodem
is configured as Data Communication Equipment (DCE), just like the Hayes
Smartmodem 2400.  The serial ports of all terminals and most computers are
configured as Data Terminal Equipment (DTE).

Each type of computer requires a special cable with a male (with the pins
sticking out) DB-25 connector on one end to plug into the faxmodem, and
the appropriate connector for your computer or terminal on the other end.
Therefore, if your computer is configured DTE (and most are), you should
ask for "a DTE-to-DCE straight-through cable with a male DB-25 connector
on one end, and the appropriate connector for your computer or terminal on
the other end".  The cable should be shielded.

Some computers (but not many) are configured DCE instead of the normal
DTE.  For these computers, instead of a straight-through cable, you would
ask for "a null-modem cable" (sometimes called a "crossover cable" or a
"modem eliminator cable").  "See Faxback Document Number 5763 for
Pinouts."

Making the Serial Connection

Once you have the proper cable to connect the faxmodem to your computer,
the most difficult part of the job is done.

To complete the serial connection, just plug the cable into the connectors
on the faxmodem and the computer, and if the connectors have locking
screws, turn them until they are tight (but not too tight) to hold the
connectors in place.

The Phone Line and Telephone Connections

There are two standard modular phone jacks (RJ11C) on the faxmodem.  One
of these jacks goes to the wall jack where you would normally plug in a
standard single-line phone. If you would like you may plug a standard
single-line phone into the other. You don't need to plug in a phone to use
the faxmodem, but you may find it convenient to have a phone beside your
computer.

The two phone jacks on the faxmodem are interchangeable. You may plug the
telephone or the cord connecting the faxmodem to the phone line into
either jack.

The cord provided for connecting the faxmodem to the phone line has a
modular RS11 plug on both ends.  If you phone system does not have modular
jacks, you will need a modular adapter, sold at most hardware stores or
any place that telephone accessories are sold.

(smc-01/10/94)