If you have an iMac, iBook, or a G3/G4/G5 computer that does not have a serial port, there are a few options available for getting your ULI or Serial Box Interface to work with it. This document is meant to advise of many of the options we are aware are available. Please note that we are now shipping our new LabPro Interface which does not need an adapter, as it has built-in USB support.

Note: New model Macintosh computers starting in January 2006 using Intel processors do not support Mac OS 9 applications or classic mode. Since Logger Pro 2 only runs in “Classic” mode, and Logger Pro 3 does not support the ULI or Serial Box Interface, there is no way to use older Vernier interfaces on Intel-based Mac computers.

Note: There are no USB/serial converters that will work with the Serial Box Interface and Windows 2000, XP, or Vista.


This will not work on new Intel-based Mac computers. For G3/G4/G5 computers, the fastest and easiest way to get your interface working on your USB computer is to use the Keyspan Twin USB to Serial adapter. We have tested the Keyspan on Mac computers and have had good results. These devices sell for about $80 each, and you will need one adapter for each interface.

To make a ULI or Serial Box Interface work, you will need:

-Mac OS 8.6 or newer

-Software drivers for the Keyspan. These are included on the CD that comes with the Keyspan device, and updated drivers are available at www.keyspan.com/downloads

Note that Keyspan makes both a Mac OS 9 and Mac OS X driver. You should install ONLY the Mac OS 9 driver. You will probably need to rebuild your desktop after installing these drivers (see details below).

We do not sell the Keyspan adapter. Keyspan products are available at:

(510) 222-0131

The long answer:

There are several other options for getting serial devices to work on USB computers. Our test results are summarized below, listed by device name. All of the devices that we list as recommended work with ULIs, Serial Box Interfaces, and TI-Graph Link cables. The Keyspan is our preferred solution, but we can’t guarantee that it will work in every possible configuration.

Keyspan Twin USB to Serial Adapter: www.keyspan.com (~$80)

This device connects to one of the USB ports on your computer and emulates a printer port and a modem port. We recommend that you use Logger Pro version 2.2.1.

Keyspan makes both a Mac OS 9 and Mac OS X driver. You should install ONLY the Mac OS 9 driver. If the Mac OS X driver is also installed, it will prevent Classic programs from seeing the Keyspan. If you have already installed the Mac OS X driver, it will need to be removed before installing the Mac OS 9 version. After installing the Mac OS 9 drivers, be sure to rebuild your desktop. If you are booting into Mac OS 9, restart the computer and hold down the Apple and Option keys the entire time the computer is starting up. (These are usually the two keys to the immediate left of the spacebar). A message will ask you if you are sure you want to rebuild the desktop. Click OK, and it will run through a routine.

If you are booting into Mac OS X, go into the System Preferences and open “Classic”. There is an “Advanced” tab that has a button for “Rebuild Desktop.

If you have not rebuilt the desktop in a long time, your Mac usually runs better after you have rebuilt it. This refreshes the index list of files on your hard drive, including USB drivers.

When you choose �Setup Interface� in Logger Pro, which ports are available in the operating system are determined and displayed. If �No Port Foundï¿ is displayed, then the computer is not identifying the Keyspan. (Regardless of what Logger Pro is doing). Try re-installing the OS 9 version of the drivers, and rebuilding your desktop. If that fails quit Logger Pro and open the Keyspan USB Serial Assistant program, and determine why the computer cannot locate the device.

If you need to use our older programs (Data Logger, MacMotion, etc.), you will need to connect your interface to Port 1 on the Keyspan. Port 1 corresponds to the Printer port, so the software will also need to be set up for an interface on the Printer Port. All of our older programs work well with this adapter, except for ULI Timer. To do photogate experiments with a USB computer, Logger Pro is required.

GeeThree Stealth Serial Port: www.geethree.com/ (~$50)

This is a clever and inexpensive device that provides a “real” serial port, rather than an emulated one. The tower-style and iMac computers often come with built-in modems. This device installs into the inside of the computer and replaces the modem with serial port. This is a good option if you do not need the internal modem. Installation of this device is relatively simple on a G3/G4 tower, but is more complicated on an iMac. We recommend that a technician install this device. Note that there are different models of this device for different model Mac computers.

Keyspan SX Pro Serial Card: www.keyspan.com(~$180)

Keyspan makes a PCI card that provides 4 serial ports. These cards install into a slot on your tower and provide a “real” serial port, rather than emulating one over the USB device chain. Because it requires a PCI slot, this device only works with G3/G4/G5 towers. Test results with this card are excellent, but note that the card needs to be installed into your computer. On Mac towers, this is a relatively easy task, but we recommend that only people who are comfortable with this type of installation do the work. If you would like to use one of these cards with our older software (DataLogger, MacMotion, etc.), you will need to go into the Keyspan control panel and make sure that one of the ports on the card is emulating the printer port. This ensures that one of the Keyspan serial ports is named “Printer.” Our older software can only connect to an interface that is on a port named “modem” or “printer”, but Logger Pro can connect to any interface that is on any available port, regardless of the port name.

iDock USB Hub with Swivel Base (~$180)

This device is swivel base for an iMac that also acts as a USB to serial converter and a USB hub. This is a good option if you plan to connect several different USB and serial devices.

In our testing, the following models did not work well with the ULI or Serial Box Interface:
– Belkin F5U103-MAC
– Entrega (~$50)
– Ariston iSerial 2 (~$190)

USB troubleshooting tips:

1. Do not connect your USB to serial adapter through a USB hub. We recommend that you connect the USB to serial converter or LabPro interface directly to the computer. Some hubs do not provide the same power to the USB port that the computer USB port does, which can cause intermittent connection problems. Plug the device into USB port #1 on the computer, and put the keyboard in USB port #2. This is particularly important on original (bondi blue) iMac computers.

2. Check the version of the drivers that you are using. We generally recommend the latest driver version from the device manufacturer, but you may want to check the compatibility list for the driver that was tested with your device. Manufacturers of these devices often release updated device drivers which may not necessarily work better with ULIs, Serial Boxes, or TI-Graph Link cables.
Apple improved the way newer versions of the operating systems handle USB device drivers compared to older versions. If you need to upgrade to OS 8.6, it is available from Apple:

Other operating system updates are also available on this website if you change directories.