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Dude, Where's My Serial Port?

Computer manufacturers are moving away from the RS-232 serial port in favor of the faster Universal Serial Bus (USB) port. This may present a problem if you need an RS-232 port to transfer data between a computer and a LI-COR instrument. If your computer does not have an RS-232 port, simply use a Serial-to-USB adapter to establish the connection. This allows the USB port to transfer data using an RS-232 cable. Serial-to-USB adapters are available from most computer supply stores, and adapters that have been tested with LI-COR instruments can be ordered directly from LI-COR (p/n 6400-27).

To install the Serial-to-USB adapter:

1. Plug the USB end of the adapter into a USB port on the computer (be sure that the RS-232 end of the adapter is not connected to anything yet). If this is the first time the adapter has been used on the computer, a "New Hardware Found" message will be displayed as the computer determines how to use the new hardware.

In most cases, the operating system will find a generic driver and indicate that the hardware is ready to use. If the operating system does not find the correct driver, insert the CD-ROM that was provided with the adapter and direct the operating system to locate the driver on the CD. Follow any additional instructions that are included with the adapter.

2. After the computer recognizes the adapter, you will need to determine the serial (COM) port designation assigned to the Serial-to-USB adapter.

a. There are several ways to find this information, but one of the easiest is to click on the "Start" menu and then click "My Computer". Under the "System Tasks" heading on the left, click on "View System Information".

The "System Properties" window will open. Click on the "Hardware" tab and then the "Device Manager" button.

b. In the "Device Manager" window, click the "+" by the "Ports (COM & LPT)" heading. Identify the appropriate COM port and record its number. Typically, it will be called "USB Serial Port (COM#)" and the # indicates the number used to identify the COM port.

3. Plug the RS-232 end of the adapter into the RS-232 port on the instrument or into a serial cable attached to the instrument.

4. To connect the LI-COR instrument to the computer, follow the instructions provided with the instrument. For many LI-COR instruments, the "Connect" command is initiated with the "Connect" button on the toolbar, or it may be found under the "Remote", "File", or "Connection" menu, depending on which instrument you are using.

5. After initiating the connection, select the appropriate COM (serial) port by entering the number recorded in step 2b. Then proceed with establishing the connection by following the instructions for your instrument. Note: Some Serial-to-USB adapters may provide too weak a signal or otherwise be incompatible. If the Serial-to-USB adapter is configured correctly but still is unable to establish a connection, consider another adapter. Adapters that have been tested with LI-COR instruments can be ordered directly from LI-COR (p/n 6400-27).

More detailed instructions for using a Serial-to-USB adapter with the LI-8100, LI-6400, or LAI-2000 are available at the
LI-COR Technical Resources Library.