How to Identify Ports on a Computer using Device Manager

Author Laplink Software on January 27, 2012 | Print | Bookmark
Last updated on April 6, 2012

Document relates to: All Laplink Products


I'm uncertain which port I need to use to make a successful Laplink connection. Can you help?


Laplink connections can be made over 3 types of cables; Serial, Parallel and USB. Certain operating systems do not support each cable type, however. For a complete listing of Laplink-brand cable options (including Windows compatibility), please Technical Document 708: Which USB Cable do I Have?

Serial Port

serial port is male in gender, and has either 9 pins or 25 pins. The shape of the port is slightly D-shaped. A serial computer port may be used for a mouse, external modem, scanner, or other linking software such as for a personal data assistant (PDA). 

Serial Port

NOTE: Do not mistake the computer's Parallel port for a serial port. Only very old computers have a 25-pin serial port. You cannot attach the wide end of the Laplink serial cable to a parallel port, nor can you attach a gender-changer adapter to force the cables to connect. This is not supported by Laplink technicians and will not work since the port communication method is different between serial and parallel ports.

On most computers, there are 2 ports and they can be marked as COM, SER, with a symbol representing 10101, or completely unmarked. ON moderately old computers, is also very common for computer manufacturer’s to have installed 2 physical serial ports, but to leave one port disabled in the BIOS. On newer computers, there may be onely one serial port, or none at all (especially on a lpatop). Also, for newer computers, it's not uncommon for the serial port to be left disabled in the BIOS, which frees up the resources for other devices. Consult your product specs or PC manufacturer for more information. 

Before using a serial port and Laplink's blue cable to make a connection, you need to locate a port that is available physically on the back of the computer and enabled within Windows configuration. Note: Laplink technicians will not support any connection using special port adapters or gender-changer devices. If both of your PC's do not have compatible, functional serial ports, you must switch to a different cable type or connection method. 

There are 4 steps to naming the external serial ports on a computer:

  1. Count the number of serial devices on the back of the computer. These include external serial ports and internal modems. The phone jack ports on a card in a slot can identify an internal modem. An serial port may have a mouse or hand-held computer cradle attached to it.

  2. See how Windows is detecting the available devices from Device Manager:
    1. Open Device Manager. See Technical Document 359: How to Open Windows Device Manager for more information. 
    2. Locate the Modem line, click on the plus (+) sign to expand,

    3. Click to highlight on the name of the installed modem.

    4. Click on Properties, and then the Modem tab. The name of the modem's port will be listed. Write down this information.

    5. Click on OK to close the modem properties.

    6. Locate the Ports (COM and LPT) line, click on the plus (+) sign to expand. The ports recognized by Windows will be listed here. Write down any port names that are listed as Communications Port (COMx), where x is the number of the port.

  3. If the computer has an infrared port, it's port name needs to be determined. This is usually configured in the computer's BIOS utility.

  4. Compare the results. There must be one port name for each serial device. If there are more ports than port names, then one of the serial ports is disabled in the computer's BIOS. Consult your computer's user guide for steps on how to enable the port.

  5. If all ports can be accounted for, but you are still uncertain as to how the ports are named, systematic trial and error is the best method to use. For example, two unnamed ports are on the computer, and Windows says that they are named COM2 and COM3. Using Laplink, enable first COM2, then COM3 in Port Setup. With the cable attached to a port, see if Laplink connects. If so, then mark the attached port as COM2. If not, return to Port Setup and try COM3. If neither enabled port makes a connection, try moving the cable to the other port and begin again.

Parallel Port

parallel port is female in gender, and has 25 pins. The shape of the port is slightly D-shaped. This is the same port as where your printer attaches. On most computers, there is only 1 port and it can be marked as LPT or with a printer symbol.
Parallel Port

Note: The Laplink parallel cable is proprietary, and must be used to connect over the LPT port.

Before using a parallel port and Laplink's yellow cable to make a connection, you need to locate a port that is available physically on the back of the computer and enabled within Windows configuration. It is very unusual for more than one LPT port to be installed on a computer and if so, has usually been done by a computer owner rather than the manufacturer. Using the information from Device Manager's Ports (COM and LPT) line as described above, it is easy to determine the port name for a parallel port. If you're still uncertain, check the settings for your printer. 

USB (Universal Serial Bus) Port

USB: A USB port is a slot port, approximately ½" long. On most computers there are 2 ports, and can be marked with a symbol that represents daisy chaining or networking. This type of port will be found only on computers that have been built after 1997.

USB Port

Before using a USB port and Laplink's USB cables to make a connection, you need to locate a port that is available physically on the back of the computer and enabled within Windows configuration. USB ports are not named in the same manner as serial or parallel ports. To confirm that a computer's USB ports are available, use the computer's user guide for steps on how to check the computer BIOS. Additionally, check Device Manager to ensure that it lists the Universal Serial Bus as a device. 

Note: Laplink USB cables are proprietary and must be used for connections using the USB ports. Several USB cables have been released by Laplink, Inc. See our Cable Drivers page for more information.

This Article can be found by searching for:

Keywords:   Cable: Parallel, Cable: Serial, Cable: USB, Connections: Cable, How To: Windows, Product: Compatibility

Platforms:   Win95, Win 98/SE, WinNT, WinME, Win2k, WinXP, WinVista, Win7

Article#: 117

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Category: Cables

Last updated on April 6, 2012 with 12959 views

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