1G The Easy Way to Make a 1G USB Datalogging Cable

Making your own USB data logging cable is just as easy, if not easier than making the standard serial cable. It is also more cost effective since the DB-9 serial version would require a USB to RS232 adapter, unless you have a laptop with a serial port. I selected this particular cable because it also has built in RX and TX LEDs. With that being said, here's what I did for less than $30.

Parts Required:

QTY-1 FTDI USB to RS232-WE-1800-BT_0.0 (Available @Mouser Electronics) USB-RS232-WE-1800-BT_0.0 FTDI Cables (Cable Assemblies)
QTY-1 1N914 Diode
QTY-1 10k Resistor
QTY-3 3" Lengths of wire 18-24 AWG w/ header pins (I pulled mine from a spare connector)
QTY-1 (Optional) ALDL connector

Tools and Supplies Required:

Soldering Iron
Solder
Electrical Tape
Heat Shrink Tubes

PDF Documentation: http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USB_RS232_CABLES.pdf

The link will provide you with the color coded wire pin out so you know which wires are connected to the pins of the embedded RS 232 converter. In addition, the applicable driver(s) software is listed, as well as a link to the download. The PDF says there are two drivers, the VCP, and the D2XX which probably not necessary, unless the logging program used requires DLL in the cable interface.

The basic layout of the cable is the same as the standard serial, depending on if you are making a PC or PDA version. I drew a little diagram that shows how the configuration goes for the PC setup. The Green, Red, and Brown wires are not used at all for this application, so they were bent back out of the way and trimmed in staggered lengths to avoid them shorting on one another.

All the components were kept inline to keep the design slim, and wrapped it with a nice protective coat of electrical tape when I was finished, which also provides the needed rigidity to help safeguard against damage to the components and solder joints.

I already had the driver for the cable on my PC from FTDI, so when I plugged in the cable it was automatically configured. Then I hooked it up in the car, and tested the cables connectivity with TunerPro RT, Palm Emulator/MMCD, TMO, and EvoScan. It works with all of the logging software I've tested it with so far! This cable with shipping cost me less than $30 to make.The price including the diode, resistor(already had but price included), and probably the ALDL, by the time it's pillaged from the junk yard. The header pins and wire extras, so no cost to me there.