Lesson 1: Understanding Connection Types

As a desktop support technician (DST), you will often be approached by users who are having trouble with devices that are attached to their computer. From an application support standpoint, you may be faced with questions about why a user cannot print a document, scan in an image, or get a handheld device to work. To support locally attached devices, it is important that you first understand how they are attached. This lesson introduces you to the common connection types available on modern computers.

After this lesson, you will be able to

• Identify the common ports available on most computers.

• Explain the use of each port type and identify the peripherals that use the port types.

• Identify common problems associated with each type of port.

Estimated lesson time: 15 minutes

Understanding Ports and Connectors

Every computer has several different types of ports available. Typically, ports are accessed from the back of the computer, although some computers also have ports on the front. These ports offer a place to connect portable devices such as printers, scanners, keyboards, and mice. The following are the six common types of ports that you will work with:

• Serial

• Parallel

• Universal serial bus (USB)

• FireWire (IEEE 1394)

• Infrared Data Association (IrDA)

• Wireless

The next several sections discuss each type of port in detail.

Note

Obviously, there are more types of ports than those listed in this section. You are likely to see specialized ports, such as network or modem ports for network cables and modems, display ports for monitors, and audio jacks for speakers and other audio devices. However, this section focuses on multifunction ports—those to which different types of devices can be connected.

Serial Port

Almost all computers come with a serial port. Serial ports were, at one time, the primary way in which data was transferred between the computer and its peripheral devices. Today, serial ports are still used to connect some mice and keyboards, but they can also be used to connect older modems, Global Positioning System (GPS) hardware, and musical synchronizers that offered only a serial connection when they were manufactured. A serial port transfers data between devices one bit at a time, which is quite slow; thus, serial ports are unlikely candidates for peripherals needing fast transfer rates.

The cables that are used with serial ports vary. When connecting a printer to a serial port, a special type of serial cable called a null modem cable is needed. Special conversion cables can be purchased, too, and these cables can connect a USB device (among other things) to an available serial port.

Many end users who have older computers have only serial ports, and these users must have a way to connect their newer devices to their older computers’ serial ports. Because of this, manufacturers have created devices and converters that can connect to these ports for backward compatibility. These devices include (but are not limited to) the following:

• PDAs, Pocket PCs, and other personal organizers

• Synchronization cradles for PDAs and other personal organizers

• Card readers

• Digital converters

• Digitizer tablets

• Serial-to-USB adapters

When troubleshooting a device that connects by using a serial port, always verify that there is not another faster port available. If there is not, verify that the serial port is functional by plugging in another device (such as a mouse), that the connection to and from the peripheral and the computer is solid, and that the cable that connects the two is not worn or damaged.

Exam Tip

If you are working with a computer that has older serial-based devices such as modems, a common problem is that different serial devices may be configured to use the same system resources (resources such as interrupt request, or IRQ, numbers). If a mouse or modem is not recognized by Windows, or if the mouse pointer behaves erratically when using a modem, use the Input Devices And Modem troubleshooters available in the Help and Support Center.

Parallel Port

Almost all computers come with a parallel port. Parallel ports have 25 pins and may be referred to as parallel ports or Centronics ports (after the company that designed the original specification). You most often use parallel ports to connect print devices, and they are common ports for connecting print servers. You can also use parallel ports to connect Zip drives, but you probably will not find many PDAs or similar devices connected there. Parallel ports send data one byte at a time.

USB Port

Almost all newer computers come with two or more USB ports. USB 1.1, which supports 12 Mbps data transfer, is used to connect a myriad of devices. USB 2.0, which supports transfer rates up to 480 Mbps, is quickly becoming standard equipment on all new computers. Connecting a USB 2.0 device to a USB 1.1 port will generally produce problems and create error messages, but it also slows the transfer rate down to USB 1.1 levels. Devices can include printers, scanners, flash drives, external drives, digital cameras, PDAs, and handheld devices.

You can also use USB ports to connect these PDA peripherals:

• Synchronization kits

• Charger kits

• Cradles

• Adapter cables

When you troubleshoot a device that connects by using a USB port, always verify that there is not another faster port available, such as FireWire. If there is not, verify that the port is functional by plugging in another device (such as a printer, scanner, or flash drive), ensure that the connection to and from the peripheral and the computer is solid, and verify that the cable that connects the two is not worn or damaged.

FireWire Port

Many newer media centers and high-end computers now come with FireWire ports (often called IEEE 1394 ports, after the Institute of Electrical and Electronics Engineers standard that defines the technology). FireWire can transfer data at a rate of 400 Mbps or 800 Mbps. FireWire is used mainly for video transfer from digital movie cameras, but it will soon become a popular option for newer PDAs and handhelds, including cradles, chargers, and synchronizers.

When troubleshooting a device that connects by using a FireWire port, always verify that the port is functional by plugging in another device (such as a digital camera), ensure that the connection to and from the peripheral and the computer is solid, and verify that the cable that connects the two is not worn or damaged.

IrDA Ports

Many newer media centers and high-end computers now come with IrDA ports. IrDA is another type of port used to transfer data between devices. IrDA data transfer requires a clear line of sight between devices and that the devices should be in close proximity to each other. IrDA ports are found on many devices, including the following:

• Media centers

• PDAs, handhelds, and portable computers

• Printers

• Digital cameras

• Other devices that connect and share information and data

When you troubleshoot a device that connects by using an IrDA port, always verify that the port is functional and that it is transmitting and receiving data, that the connection to and from the peripheral and the computer is within the required proximity, and that the two devices have a clear line of sight. You might also need to verify that the connection is enabled by using the Network Connections window.

Wireless Access Points

Wireless local area networking is a technology that allows computers and other network devices (such as smart displays, PDAs, and handheld computers) to transfer data without cables or wires. A wireless access point is a device that allows users to connect to a network by using a wireless networking card that is installed in their computing device. The wireless access point functions as a bridge between wireless devices and allows those devices to communicate. Depending on the environment, one access point can offer up to 300 feet of wireless coverage.

Many devices have wireless networking cards and can communicate with a wireless access point, including the following:

• Media centers

• Smart displays

• Laptops

• Handheld computers, PDAs, and Tablet PCs

• Printers

When you troubleshoot devices that use a wireless access point, verify that the connection is enabled and functioning by using Network Connections, ping the access point’s Internet Protocol (IP) address, verify the signal strength by hovering over the network connection icon in the notification area, try changing channels if applicable, ensure that the clients are in the required range, and verify that connectivity (if any exists to another network) is connected securely and properly.

Troubleshooting Ports and Connections

Every type of external device that is connected to your computer, from printers to scanners to digital cameras, is either connected to a port by a cable or connected wirelessly. When you troubleshoot locally attached devices, you must be able to isolate the problem before you can propose a solution. The following list shows some of the problems that can prevent a device from working properly within an application:

• The application is not properly configured to use the device. If a device seems to be working but is not providing the results that a user expects, the problem may well be in the application settings, not with the device itself. For example, a user might print a document from Microsoft Word and complain that certain parts of the document do not print (such as reviewer comments). In this case, you would need to configure Word to print comments.

• The device is connected and functions but is not properly configured in Windows. You can use Device Manager (from the Start menu, right-click My Computer and choose Properties, click the Hardware tab, and then click Device Manager) to determine whether a device is enabled in Windows XP, has drivers installed, and is working properly. For more information on using Device Manager, see Microsoft Knowledge Base article 314747.

• The device does not have a proper driver or other software installed. Without a driver installed, Windows cannot interact with a device. Windows XP ships with a large number of hardware drivers but may not have built-in drivers for hardware that was shipped after the release of Windows XP.

• The device is not turned on.

• The device is not properly connected to the computer, or the cable used for the connection is damaged.

• The device itself is malfunctioning.

The Windows XP Help and Support Center offers a number of troubleshooters that can help you isolate and resolve issues with connected devices. You can also work through the troubleshooters yourself to learn a lot about the process of troubleshooting connected devices. You can access a list of troubleshooters using the following steps:

1. From the Start menu, select Help And Support.

2. In the Help And Support Center window, select Fixing A Problem.

3. In the Fixing A Problem list on the left side of the window, select Troubleshooting Problems.

4. In the Troubleshooting Problems list on the right side of the page, select List Of Troubleshooters.

   Exam Tip

   When you come across a device that is not working as expected, start troubleshooting from the highest interface level (the application) and work your way to the lowest level (the device itself). Check application configuration, then Windows configuration, then the device driver or other software, then the port, then the cable, and then the device.

Real World: Configuring the Computer’s BIOS

A computer’s BIOS is built-in software that contains the code that is required to boot the computer and control the keyboard, display, disk drives, and serial communications on a computer. The BIOS is stored on a chip that is connected to the computer’s motherboard, so it is not affected by disk drive failures.

Some products (often printers or imaging devices) require that specific ports be configured in the BIOS before the products can be used. Generally, configuring the BIOS involves booting the computer and pressing Del or F1, F2, F3, or another function key before the operating system has started. The documentation that comes with the device will have specific directions if configuring these ports is required.

The BIOS also allows you to configure the hardware settings for both serial and parallel ports (the base I/O address and interrupt) in the BIOS setup utility. You can enable or disable bidirectional communication, Enhanced Capabilities Port (ECP), and Enhanced Parallel Port (EPP) for the parallel port, or enable or disable serial and parallel ports altogether. When troubleshooting devices that use serial or parallel connections, make sure that you verify that the ports are enabled in the BIOS.

Practice: Configure Ports

In this practice, you will change the port speed of a serial port. You will also disable and then re-enable a parallel port.

Exercise 1: Change the Port Speed on a Serial Port

1. Log on to Windows XP using an account with administrator privileges.

2. From the Start menu, select Control Panel.

3. In Control Panel, select Performance And Maintenance.

4. In the Performance And Maintenance window, select System.

5. On the Hardware tab, select Device Manager.

6. Expand Ports (COM & LPT), right-click Communications Port (COM1) and choose Properties, and then select the Port Settings tab.

7. On the Bits Per Second drop-down list, choose 128000.

8. Click OK and close all the open dialog boxes.

Exercise 2: Disable and Re-enable a Parallel Port

1. Log on to Windows XP using an account with administrator privileges.

2. From the Start menu, select Control Panel.

3. In Control Panel, select Performance And Maintenance.

4. In the Performance And Maintenance window, select System.

5. On the Hardware tab, select Device Manager.

6. Expand Ports (COM & LPT), right-click Printer Port (LPT1), and choose Properties.

7. On the General tab of the Printer Port (LPT1) Properties dialog box, in the Device Usage drop-down list, select Do Not Use This Device (Disable). Click OK.

8. In the Device Manager window, note that the icon for Printer Port (LPT1) has a red X on it, indicating that the device is disabled. Right-click Printer Port (LPT1) and choose Properties.

9. On the General tab of the Printer Port (LPT1) Properties dialog box, in the Device Usage drop-down list, select Use This Device (Enable). Click OK.

10. Close all open dialog boxes.

Lesson Review

The following question is intended to reinforce key information presented in this lesson. If you are unable to answer the question, review the lesson materials and try the question again. You can find answers to the question in the “Questions and Answers” section at the end of this chapter.

1. For each of the connection types listed, match its name on the left with its description on the right.

   1. Serial	A. Sends data at 12 Mbps.
   2. Parallel	B. Sends data one bit at a time.
   3. USB 1.1	C. Sends data at 400 Mbps or 800 Mbps.
   4. FireWire	D. Can transmit data between wireless devices up to 300 feet apart.
   5. Wireless access point	E. Sends data one byte at a time.

Lesson Summary

• Common port types that are available on most computers include serial, parallel, USB, FireWire, IrDA, and wireless.

• When you troubleshoot connections, ensure that the device is enabled and listed as working properly in Device Manager. If the device is enabled, the problem is most likely with the application. If the device is not listed as working properly in Device Manager, make sure that the device is turned on, that the port is configured properly, and that the cable is in working order. You can also use the Windows troubleshooters to help isolate the problem.