Printers require a method of communicating
with the computers they serve. Communication is accomplished through
the ports on both the printer and the computer (or network device) or
by using wireless technologies (such as infrared signals). Most
printers use serial, parallel, USB, SCSI, and network cables and ports
to receive information from computers.
Serial
Serial ports are usually found on dot matrix printers that do not
require high-speed transfers of data. Transmitting information
serially involves single characters being transmitted one at a time.
Serial ports are D-Shell ports that are categorized as being either
male or female and also by the number of pins available for each port.
Popular serial cables include 9-pin on both ends, 25-pins on both
ends, or a combination of the two. Usually, the ends of the printer
cables are secured to the ports on the printer and PC with
thumbscrews. The maximum length of serial cable is 50 feet (18m).
Parallel
Printers that use parallel communication have faster data transfer
rates than serial printers because parallel data transfer moves
multiple bits of information in a single cycle. This provides a wider
path for information moving to or from the printer.
IEEE 1284 is the
current standard for parallel printer cables. Other standards such as Enhanced
Parallel Port (EPP) and Enhanced Capabilities Port (ECP)
allow bi-directional communication across the parallel cable. Parallel
printer cables have two unique ends: a 1284 Type-A 25-pin DB 25
connector and a 36-conductor Centronics connector.
The Type-A connector connects to the PC (or daisy-chained peripheral)
and has two screws that should be hand-tightened. The Centronics
connector connects to the printer and should be secured in place with
the port clips. The maximum length for IEEE 1284 cables is 15 feet
(3M).
SCSI

Small Computer System Interface (SCSI) is a type of interface
that uses parallel communication technology to achieve high data
transfer rates. There are many types of SCSI with the most popular
being SCSI 1 (plain SCSI), SCSI 2 (wide SCSI), and SCSI 3 (fast SCSI).
SCSI printers and computers require the proper cabling for the ports. These ports can be DB 50 (male or female), MiniDB 50 (male or female),
and DB 68 (male or female).
USB

Universal Serial Bus is a very popular communication type for not only
printers but also other devices due to its speed and ease of setup.
Newer operating systems offer Plug and Play USB support. When a device
is added to a computer system via USB, it is automatically detected,
and the driver installation process begins. A USB cable is a four-wire
cable that also has two unique ends. One end of the USB is the wider,
slimmer end that connects to the PC. The other end, which is square,
connects to the printer. These ends are keyed so that they can only
fit one way into each port.
FireWire

FireWire, also known as i.LINK or IEEE 1394, is a high-speed,
platform-independent communication bus. It interconnects digital
devices such as digital printers, scanners, digital cameras, hard
drives, and so on. Developed by Apple, FireWire was designed to allow
peripherals to seamlessly plug into a computer. It also allows a
device such as a printer to be hot-plugged. FireWire provides a single
plug-and-socket connection on which up to 63 devices can be attached
with data transfer speeds up to 400 megabits per second (Mbps). IEEE
1394 implementations are envisioned to replace and consolidate modern
serial and parallel interfaces, such as Centronics parallel, RS-232C,
and SCSI. The first printers to be introduced with FireWire are just
beginning to come on the market.
Network
Network printers are now popular in the workplace because they act as
shared resources for all users on the network. Users are not required
to have their own printers. These printers offer many
options (such as LAN fax, duplex, and finishers) and have high-speed
outputs. Connecting a printer to the network requires the correct type
of cabling that is compatible with the existing network. Most network
printers ship with an RJ-45 interface for connection into an Ethernet
network. Other connection options include BNC and Token Ring ports.
The maximum length of a Cat 5 cable to connect a printer to the
network is 100 meters.
Infrared
Current wireless printing technology is built upon infrared
technology. This technology uses a spectrum of light that is invisible
to the human eye. For infrared communication to take place between a
printer and a computer, transmitters and receivers are required on
both devices. When setting up an infrared printer, there must be a
clear line of sight between the transmitters and receivers on both
devices with a maximum distance of three meters.