Jornada Cradle Modification.

If you are worried about Warranty, this page is not for you !

The Jornada has a Serial Port and comes standard with a Serial cable designed to connect directly into a desktop or laptop 9 pin RS-232 . It is wired in a null modem manner to facilitate communication between the Jornada and PC.

The program I am developing  requires the Serial port to be a true PC COM1 port (i.e. DB9 Male Plug) and the wiring should be the same as a regular COM port on a PC.

First I tried adapters, while they worked OK they were big and awkward. I also needed the USB connection to the PC for ActiveSync to update my files. This meant using the cradle. As the standard cradle delivered with the unit is USB only there is no way to get at the COM1 RS-232 port ! I checked the HP web site and sure enough they make a Serial Cradle, but it does not have USB, and as my program needs the COM1 there would be no connection to the PC at all.

I then decided to buy a Net work card and found it works very well so ActiveSync can now update the files and it freed up COM1 for my application. 

I used that for a day or two, but did not like the arrangement. The cradle is a nice device, it puts the Jornada at a convenient angle and makes developing a program much more pleasant. see MCAce.exe

So the next step was to get a Serial Cradle and use the Network card for active sync.

As I already had a serial cable and a USB cradle I studied the arrangement and found it was a simple matter to turn the cradle into a dual purpose Serial and USB cradle. Both the USB and Serial ports can be used at the same time.

 The modified cradle, I call it "The Developers Cradle"

Here's how I did the conversion using the parts that came with the standard Jornada 548.

Dismantle the Serial plug and remove the 12 pin connector.

Pry off the shell.

Dismantle the cradle, there are three screws holding the heavy metal base, and 6 very small screws that hold the back of the cradle together.

Remove the connector, notice this one only has 4 pins in it, and the serial cable connector has all pins. the object here is to swap these two connectors and add a cable for the COM1 connection.


The cradle connector is mounted on a small PCB, it has all the connection ready for the RS-232 cable.

Next prepare the Serial cable for connection to the cradle PCB. Cut off the remains of the serial connector and

strip, twist and tin the wires. I added a pig tail to the braiding and insulated it.

I did not intend to leave the DB9S on the cable and so both ends should be  prepared the same way.


Ty-wrap the new cable to the USB cable and connection as follows.


As the connections are not marked in any way, I had to make a decision about pin numbering. So my pin numbering may not be the correct numbering as compared to the original manufacturer numbering.

Using part of the original Serial Cable the connection list between the new DB9M (male) as normal COM1 and Jornada Connector (using my pin numbering). Note! wire coloring may be different, it depends on production.


How to Make a Real COMx Cable

    If you just need to convert a regular Jornada Serial Cable to turn it into a "Normal COMx" cable, then simply use

    the table shown above. Cut off the Female DB9, strip back and prepare the wires, and connect a Male DB9 .

    If your wire coloring is different, simply use an Ohm meter and make a table of the connections.

If HP ever makes the connectors available, it will not take long to rebuild the serial cable.

Note! Palm makes connectors readily available to developers, however at HP's developer web site there is no mention of

any hardware being available for developers, not even this kind of cradle that a developer MUST have.

You can buy Connectors here

If you have questions, send me an email.

I have modified two cradles with 100% success, however you are alone if you use this information, Ohm out the connections, double check my connection list.  If you try this and break your cradle and/or the Jornada, you have been warned.

Disclaimer:-    No warranties given or implied. Use this information at you own risk. I will not be responsible for your mistakes.

(C) Copyright 2005 Hans Wedemeyer, Houston, Texas, U.S.A. All rights reserved.

This information (text and images) may not be reproduced in any form for commercial purposes.

All trade marks are the property of their respective owners.

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