A company named Elexol makes a second generation serial-to-USB port adapter called the USBMOD3. Many newer notebook computers are being built with USB ports, and without the classic serial ports. Here are the pin connections needed to connect a USBMOD3 to the datalogging port of a Honda ECU:

Pin 4 (Vcc) is hooked to Pin 8 (Reset In) since an external device doesn't need to reset the device.

Pin 9 (Enumeration Power) is hooked to Pin 10 (Reset Out) for bus powered operation per the user's manual.

Pin 18 (Power Control) is wired to ground to select bus powered operation per the user's manual.

Pin 23 (Data Set Ready) is hooked to Pin 24 (Data Terminal Ready) for modem control handshaking.

Pin 25 (Clear To Send) is hooked to Pin 26 (Request To Send) for modem control handshaking.

Pin 27 (RXD) is temporarily hooked to Pin 28 (TXD) for a loopback test.

Pin 12 (VIO) hooked to Pin 13 (V+) to power the UART IO properly.

You can get the USBMOD3 driver from FTDI.

After you plug in the USBMOD3, you can test that it is recognized by your MS Windows computer by checking Device Manager under Ports to see which COMn: port is mapped to which USB port. You can set the serial port settings such as baud rate and parity by opening the Properties window and selecting the Port Settings tab.

You can test the USBMOD3 by opening Windows Hyperterminal, and pointing it at the proper serial port, the one that you saw in Device Manager. With Pins 27 and 28 connected fot the loopback test, everything you type in Hyperterminal will echo to the Hyperterminal window on your PC.

After that test is successful, all you need to do is connect Pin 27 (RXD) to the ECU TXD signal and connect Pin 28 (TXD) to the ECU RXD signal as described at ECU Control under the How to Mod my ECU link. (Thanks Nicolas)

-- markolson - 29 Oct 2004