Networking.docx

Virtual Printers All the print technologies that we have covered so far are physical technologies—that is, they do something to the paper to produce an image, by using ink, toner, or heat. Another concept that we need to cover is virtual printing, which sends the desired output to a file instead of...

Virtual Printers All the print technologies that we have covered so far are physical technologies—that is, they do something to the paper to produce an image, by using ink, toner, or heat. Another concept that we need to cover is virtual printing, which sends the desired output to a file instead of to paper. From the end user’s standpoint, starting the printing process is the same. They click Print in their application and the process starts. From there, though, instead of sending the output to an electromechanical device, a new file containing the output is generated. Printing to a file is nothing new; this option has been around for probably 20 years or more. You open the document (or other file) that you want to print, select Print, and a print window similar to the one shown in Figure 5.22 opens. Once there, you check the Print To File box, and then click OK. (Other programs may have you choose the option to print to file in a drop-down list of printers.) Then, choose where to save the file (just as saving any other file), and after you chose a destination, you are done. Some programs or operating systems would even let you print to an image (such as JPG) instead of a file, but the process works the same way. Figure 5.22 Print To File option 262 It used to be that people only chose this option when the printer was not available. You could print your output to a file, take the file to a different machine that had a printer available, and print the file from that machine. Now, you might ask, why wouldn’t you just take the original file from the first computer to the second and print it from the application? That would make sense, but this method allowed you to print from a second computer that didn’t have the application in which you created the file installed on it. There was one big caveat: You had to be printing to the same type of printer using the same printer driver as you used to publish the electronic print file; otherwise, it wouldn’t work. The upshot was that it was rarely, if ever, used. Another option has emerged, though, and this one is actually useful! Instead of printing to a generic file format that can be later used to produce a paper copy, you can print to a Portable Document Format (PDF) file. Basically, you are just creating a PDF file using your application’s print function. There are a few different ways to print to PDF from Windows and Windows-based applications. Some apps natively print to PDF, whereas others require you to install a third-party application that supports printing to PDF. There is no shortage of apps in the market that will do this; for example, Adobe Acrobat (www.adobe.com), CutePDF Writer (www.cutepdf .com), and Nitro PDF (www.gonitro.com) will do the trick. When you print, you will get a screen similar to the one shown in Figure 5.23. Figure 5.23 Printing to PDF 263 Select Print to PDF (or your version of it) and click Print. A window will pop up asking where you want to save the file. Save it, and a PDF file is created for you. It’s as easy as that.  Current versions of Microsoft Office products also let you create a PDF file automatically. For example, in Word, you can choose File ➢ Save As, and one of your options in the drop-down menu will be the PDF format. Another way is to click File ➢ Save & Send, and then choose Send As PDF. Another option, besides printing to PDF, is to print to XPS. An Open XML Paper Specification (XPS) file is Microsoft’s version of a PDF. It’s designed to be an open standard, like PDF, but it hasn’t really taken off in terms of popularity. In fact, with the introduction of Windows 8, Microsoft included support for OpenXPS (OXPS), which is incompatible with the XPS reader included with Windows 7. In addition, Windows 8 and newer include a native PDF reader, so it seems that Microsoft isn’t heavily invested in supporting the XPS format itself. Let’s go back to printing to an image for a minute. If your program doesn’t support printing to an image but you need the output of the file in an image format (JPG, TIF, PNG, or other), you can print the file as a PDF first, and then convert it to an image file. There are dozens of free image file converters on the web. To summarize, there are four potential options for printing to a virtual printer: print to file, print to image, print to PDF, and print to XPS. Of the four, the only one that you will likely find to be useful is print to PDF. 3D Printers In 2011, the first commercially available 3D printer hit the market. Although the word “printing” is used, the technology and process are completely different from putting ink to paper. 3D printing is really a fabrication process, also called additive manufacturing. In it, a three-dimensional product is produced by “printing” thin layers of a material and stacking those layers on top of each other. The first 3D printers were used in manufacturing environments. Over time, smaller, more economical models have been made for home use as well, although the technology still remains fairly expensive. Most 3D printers intended for the home use rolls of plastic filament to create objects, but industrial printers can use a variety of materials, including aluminum, copper, and other metals. Some enterprising soul also created a 3D printer that prints using melted chocolate. They very likely deserve a Nobel Prize. Parts of a 3D Printer They can produce complex creations, but 3D printers are relatively simple devices with few parts. For the examples here, we will use smaller 3D printers designed for home or small business use. Therefore, we’ll focus on printers that use plastic filament as opposed to other materials. The primary components are as follows: Frame Printing plate 264Extruder Cooling fan PCB circuit board Filament The frame holds the printer together. On the bottom of the printer will be the printing plate, where the object is created. The extruder heats up and melts the filament, which is used to create the object. A cooling fan keeps the extruder from overheating. A PCB circuit board will be installed somewhere, to control the movement of the extruder assembly. Some printers will also have electronic displays and a clear protective case. Figure 5.24 shows a simple MakerBot 3D printer 24. It’s relatively easy to see the frame, printing plate, display, and filament tube. 3D printers are connected to a computer using a USB cable. Figure 5.24 A 3D printer On most 3D printers, the extruder is attached to metal rods that control the position of the extruder on X, Y, and Z axes. As mentioned earlier, the extruder heats up and melts plastic filament. The extruder then moves around to create the object, adding one thin layer of material to the printing plate at a time. Figure 5.25 shows an extruder from a different 3D printer—it’s the small black block at the bottom of the image. In this image, the filament tube is seen coming from the top of the extruder assembly. Figure 5.25 3D printer extruder 265 Filament comes on a spool, much like wire, and is shown in Figure 5.26. Be sure that the filament is compatible with the printer you intend to use it with. Here are the things to consider when purchasing replacement filament: Type More than a dozen different types of plastic filament are available. The most popular are polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). Each has different characteristics—for example, ABS shrinks as it cools, so a heated printing plate is recommended. Size The most common size is 1.75 mm, but 3.0 mm filament (which is actually 2.85 mm thick) was the original size and is still used today. Color The printer doesn’t really care what color you use, but a variety of colors are available. Replacing filament is a straightforward process. The 3D printer’s app (or interface panel) will have a Replace Filament button or option. Once you start the process, the extruder will heat up and start to expel the current filament. At some point, it will tell you to replace the roll. You remove the old roll and feed the new filament through the filament tube into the extruder. After a short time, you will see the new color come through as melted filament (if you changed colors), and you can use the app or interface panel to stop the replacement. Figure 5.26 3D printer PLA filament 266 The 3D Printing Process Every 3D printer comes with its own software that helps manage the printing process; therefore, the process will differ slightly from printer to printer. The following steps are general steps taken to get from idea to 3D printed object. Design the object using a computer-aided design (CAD) program. The most well-known commercial software for this is probably AutoCAD by Autodesk. Another option is the free Tinkercad. Export the file from the CAD software. Doing so will cause the CAD program to “slice” the object into layers, preparing it for printing. The exported file will be a .STL file. This step will vary somewhat, depending on the 3D printer’s software. In many cases, the .STL file can be imported into the printer’s app, and the app will slice the file yet again, formatting the model specifically for the printer. Some apps can’t slice, though, so third-party slicing software is needed. Examples include Cura, SliceCrafter, and Slic3r. Most slicers are free, although commercial versions are available. Send the job to the printer. This is basically just pushing the Print button. The printer will perform a calibration and self-test. The extruder will heat up and calibrate its position on the X, Y, and Z axes. Printing begins. 267 Small print jobs may take over an hour, depending on the printer and size of the object. Larger jobs may take days to complete. The maximum object size will be determined by the model of printer. After the job is done, a little sanding or filing may be required to remove excess filament. A completed 3D print job (actually several jobs) is shown in Figure 5.27. In total, the objects are about 1.5″ long. Higher-end 3D printers can create components that move, such as hinges and latches. Figure 5.27 3D printed objects Installing and Maintaining Printers Odds are that if someone owns a computer, they own a printer as well. If they don’t, they have easy access to a printer at a library, work, or some other place. Many retailers and computer manufacturers make it incredibly easy to buy a printer because they often bundle a printer with a computer system as an incentive to get you to buy. The CompTIA A+ 220-1001 exam will test your knowledge of the procedures to install and maintain printers. In the following sections, we will discuss connecting printers through various interfaces, installing and sharing local and networked printers, performing printer maintenance, and installing printer upgrades.  Many inkjet and laser printers today provide several functions, including copying, scanning, and faxing. These devices go by several names, including multifunctional printer, multifunction device (MFD), multifunction product (MFP), or all-in-one printer. Printer Interface Components A printer’s interface is the collection of hardware and software that allows the printer to communicate with a computer. The hardware interface is commonly called a port. Each printer has at least one interface, but some printers have several interfaces, to make them268more flexible in a multiplatform environment. If a printer has several interfaces, it can usually switch between them on-the-fly so that several computers can print at the same time. An interface incorporates several components, including its interface type and the interface software. Each aspect must be matched on both the printer and the computer. For example, an older HP LaserJet 4L has only a parallel port. Therefore, you must use a parallel cable as well as the correct software for the platform being used (for example, a Macintosh HP LaserJet 4L driver if you connect it to a Macintosh computer). Interface Types When we say interface types, we’re talking about the ports used in getting the printed information from the computer to the printer. There are two major classifications here: wired and wireless. Wired examples are serial, parallel, USB, and Ethernet. Wireless options include 802.11 and Bluetooth. You’ve learned about the wired connections in Chapter 3, “Peripherals and Connectors,” and you will learn more about the wireless connections in Chapter 6, “Networking Fundamentals.” Here you will learn how they apply to printers. Serial When computers send data serially, they send it 1 bit at a time, one after another. The bits stand in line like people at a movie theater, waiting to get in. Old-time serial (RS-232) connections were painfully slow, but new serial technology (Thunderbolt, eSATA, and others) makes it a more viable option than parallel. While it’s quite common to see USB (another type of serial connection) printers on the market, it’s rare to find any other types of serial printers out there. Parallel When a printer uses parallel communication, it is receiving data 8 bits at a time over eight separate wires (one for each bit). Parallel communication was the most popular way of communicating from computer to printer for many years, mainly because it was faster than serial. In fact, the parallel port became so synonymous with printing that a lot of companies simply started referring to parallel ports as printer ports. Today, though, parallel printers are uncommon. The vast majority of wired printers that you see will be USB or Ethernet. A parallel cable consists of a male DB25 connector that connects to the computer and a male 36-pin Centronics connector that connects to the printer. Most of the cables are shorter than 10’. The industry standard that defines parallel communications is IEEE 1284; parallel cables should be IEEE 1284-compliant.  Keep printer cable lengths shorter than 10’. Some people try to run printer cables more than 50’. If the length is greater than 10’, communications can become unreliable due to crosstalk, which is the degrading of a signal due to electromagnetic interference (EMI). Universal Serial Bus The most popular type of wired printer interface is the Universal Serial Bus (USB). In fact, it is the most popular interface for just about every peripheral. The convenience for printers269is that it has a higher transfer rate than older serial or parallel connections, and it automatically recognizes new devices. And, of course, USB is physically very easy to connect. Ethernet Many printers sold today have a wired Ethernet interface that allows them to be hooked directly to an Ethernet cable. These printers have an internal network interface card (NIC) and ROM-based software that allow them to communicate on the network with servers and workstations. As with any other networking device, the type of network interface used on the printer depends on the type of network to which the printer is being attached. It’s likely that the only connection type that you will run into is RJ-45 for an Ethernet connection. Wireless The latest trend in printer interface technology is to use wireless. Clearly, people love their Wi-Fi because it enables them to roam around an office and still remain connected to one another and to their network. It logically follows that someone came up with the brilliant idea that it would be nice if printers could be that mobile as well—after all, many are on carts with wheels. Some printers have built-in Wi-Fi interfaces, while others can accept wireless network cards. Wi-Fi-enabled printers support nearly all 802.11 standards (a, b, g, n, ac), and the availability of devices will mirror the current popularity of each standard. The wireless technology that is especially popular among peripheral manufacturers is Bluetooth. Bluetooth is a short-range wireless technology; most devices are specified to work within 10 meters (33 feet). Printers such as the HP Sprocket series and Officejet 150 mobile printers have Bluetooth capability. When printing with a Bluetooth-enabled device (like a smartphone or tablet) and a Bluetooth-enabled printer, all you need to do is get within range of the device (that is, move closer), select the printer driver from the device, and choose Print. The information is transmitted wirelessly through the air using radio waves and is received by the device.  When Wi-Fi is used to connect printers to a network on a more permanent basis, it is known as infrastructure mode. Wi-Fi and Bluetooth can be used to connect a printer temporarily to a single computer (or mobile device), and the connection does not have permanent status. This type of configuration is known as an ad hoc network connection. Interface Software Now that we’ve looked at the ways that you can connect your printer, it’s time to face a grim reality: Computers and printers don’t know how to talk to each other. They need help. That help comes in the form of interface software used to translate software commands into commands that the printer can understand. There are two major components of interface software: the page-description language and the driver software. The page-description language (PDL) determines how efficient the printer is at converting the information to be printed into signals that the printer can270understand. The driver software understands and controls the printer and must be written to communicate between a specific operating system and specific printer. It is very important that you use the correct interface software for your printer. If you use either the wrong page-description language or the wrong driver software, the printer will print garbage—or possibly nothing at all. Page-Description Languages A page-description language works just as its name implies: It describes the whole page being printed by sending commands that describe the text as well as the margins and other settings. The controller in the printer interprets these commands and turns them into laser pulses (or pin strikes). Several printer communication languages exist, but the three most common are PostScript, Printer Command Language (PCL), and Graphics Device Interface (GDI). The first page-description language was PostScript. Developed by Adobe, it was first used in the Apple LaserWriter printer. It made printing graphics fast and simple. Here’s how PostScript works: The PostScript printer driver describes the page in terms of “draw” and “position” commands. The page is divided into a very fine grid (as fine as the resolution of the printer). When you want to print a square, a communication like the following takes place: POSITION 1,42%DRAW 10%POSITION 1,64%DRAW10D% . . . These commands tell the printer to draw a line on the page from line 42 to line 64 (vertically). In other words, a page-description language tells the printer to draw a line on the page and gives it the starting and ending points—and that’s that. Rather than send the printer the location of each and every dot in the line and an instruction at each and every location to print that location’s individual dot, PostScript can get the line drawn with fewer than five instructions. As you can see, PostScript uses commands that are more or less in English. The commands are interpreted by the processor on the printer’s controller and converted into the print-control signals. PCL was developed by Hewlett-Packard in 1984 and originally intended for use with inkjet printers as a competitor to PostScript. Since then, its role has been expanded to virtually every printer type, and it’s a de facto industry standard. GDI is actually a Windows component and is not specific to printers. Instead, it’s a series of components that govern how images are presented to both monitors and printers. GDI printers work by using computer processing power instead of their own. The printed image is rendered to a bitmap on the computer and then sent to the printer. This means that the printer hardware doesn’t need to be as powerful, which results in a less expensive printer. Generally speaking, the least expensive laser printers on the market are GDI printers.  Most newer printers can handle both PS and PCL (and GDI) and will automatically translate for you. Therefore, it’s less likely that you’ll install the wrong printer driver than it was several years ago. The main advantage of page-description languages is that they move some of the processing from the computer to the printer. With text-only documents, they offer little benefit. However, with documents that have large amounts of graphics or that use numerous fonts,271page-description languages make the processing of those print jobs happen much faster. This makes them an ideal choice for laser printers, although nearly every type of printer uses them.