HP 95LX - Page 91

Three of the most useful adapters for the HP 95LX are these:
Connects a 9-pin female (2-3-5) with a 25-pin female (3—2—7)—common for
computer serial ports. This is the adapter you get in the Connectivity Pack.
Connects a 9-pin female (2-3-5) with a 25-pin male (2-3-7). This is a common
adapter for modem connections.
Connects a 9-pin female (2-3-5) with a 25-pin male (3—2—7). This is a common
adapter for serial printer connections.
Of course, your equipment may not match these examples. To figure out exactly
what adapter(s) you need, do the following:
1. Read the manual for the device you're trying to connect to. Note which pins (or
signal lines) are used to transmit, receive, and act as signal ground; note the
size (9-pin, 25-pin, etc.) and gender of the serial connector on the device.
Evaluate what kind of device you are connecting to: A modem is a communi-
cations device—which sends on pin 3 and receives on pin 2. You want the
Transmit line (pin 2) from the HP 95LX to match with the Receive line in the
modem (and vice versa). Note that everything matches up perfectly without
swapping pins. Unfortunately the 9-pin to 25-pin adapter included in the
Connectivity Pack (type A above) , swaps pins. This means that, if you use this
adapter to get a 25-pin connection to a modem, you must use a null modem
adapter to switch the pins back the way they are in the HP 95LX. Of course,
you can use a single Type B adapter instead of the Type A adapter plus a null
modem adapter. Computers and printers are terminal devices—that send on
pin 2 and receive on pin 3. Again, you want the Transmit line on the 95LX to
match with the Receive line on the other device and vice versa. Here you need
to swap pins—which the Connectivity Pack’s Type A adaptor does. The only
modifications you may need to add to connect to a printer are gender changers
that don’t swap pins. Alternatively, a single Type C adapter will do the trick
for printer connections.
Take the information you've gathered in steps 1-2 to your computer dealer or
electronics store and look for an adapter that has one end with a 9-pin male (2—
3-5) and the other end configured to connect properly with the your device. Be
sure to notice the pin configuration of the transmit and receive lines as well as
the gender of both ends of an adapter. You may need to use a combination of
size-and-style adaptors, gender changers, and null modem adapters, to accom-
plish the task. Whatever you do, don’t use a cable (even if it has the adapters
you need on the ends). The added length of signal travel through the cable may
result in poor transmission quality.
Making the Connection 91