Editing Barcode reader (section)

== Methods of connection ==

=== Serial interfaces ===
Early barcode scanners, of all formats, almost universally used the then-common [[RS-232]] serial interface. This was an electrically simple means of connection and the software to access it is also relatively simple, although needing to be written for specific computers and their serial ports.

[[Image:Ps-2-ports.jpg|thumb|right|[[PS/2 connector|PS/2]] keyboard and mouse ports]]
As the [[personal computer|PC]] with its various standard interfaces evolved, barcode readers began to use keyboard serial interfaces. The early "keyboard wedge" hardware plugged in between the [[PS/2 port]] and the keyboard, with characters from the barcode scanner appearing exactly as if they had been typed at the keyboard. Today the term is used more broadly for any device which can be plugged in and contribute to the stream of data coming "from the keyboard". Keyboard wedges plugging in via the [[USB | USB interface]] are readily available. In many cases, a choice of [[USB]] interface types ([[USB HID|HID]], [[USB communications device class|CDC]]) are provided.

=== Proprietary interfaces ===
There are a few other less common interfaces. These were used in large [[Point of sale|EPOS]] systems with dedicated hardware, rather than attaching to existing commodity computers. In some of these interfaces, the scanning device returned analog signal proportional to the intensities seen while scanning the barcode. This was then decoded by the host device. In some cases the scanning device would convert the symbology of the barcode to one that could be recognized by the host device, such as [[Code 39]].
 	
=== Wireless networking ===
Some modern handheld barcode readers can be operated in [[wireless network]]s according to [[IEEE 802.11g]] ([[WLAN]]) or [[IEEE 802.15.1]] ([[Bluetooth]]). Some barcode readers also support [[radio frequencies]] viz. 433&nbsp;MHz or 910&nbsp;MHz. Readers without external power sources require their [[Battery (electricity)|batteries]] be recharged occasionally, which may make them unsuitable for some uses.