Barcode Scanner Interface: Connect and Communicate

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Did you know that there are multiple types of computers that you can attach a barcode scanner to?  The following post is intended to cover the most common barcode scanner interface options, primarily as they relate to the PC, but is by no means inclusive of all interface options.  It’s important to note up front that there are two main factors in scanner connectivity:  physical connection and communication protocol.

RS232 Interface

Barcode Scanner Interface: R232 DB9 Port

RS232 (commonly referred to as serial although it’s only one type of serial communication) is a communication protocol. It doesn’t tell us anything about the physical connection.  However, in practical terms, if your consumer or business PC even has an RS232 port, it’s almost certainly a 9 pin male connection.  It’s also safe to assume that you will require power from an external source.  RS232 scanner kits will almost always consist of a scanner, interface cable to 9 pin connections and a power supply.

Barcode Scanner Interface: RS232 RJ12 Port

Point of Sale systems sometimes use RS232 communication that connects via a Registered Jack, or RJ connection.  They may or may not require an external power supply.  The interface cables are wired in a specific way and the scanner itself is programmed to work with only that system.  This is known as a proprietary interface.  RS232 devices are found in the Windows Device Manager under “Ports” and have a “COM” address.  A physical port on a PC is usually COM 1.  Your software and hardware must be set to the same COM address to communicate with each other.

Keyboard Wedge Interface

Barcode Scanner Interface: PS/2 Keyboard Port

Keyboard Wedge refers to a barcode scanner sharing the same physical port as a keyboard.  Keyboard wedge refers to the physical connection (almost exclusively PS/2) and the communication protocol.  Everything scanned with a keyboard wedge scanner is sent to the host computer just as if it were typed.  This means that a user has to make sure the right window is in focus on their computer and the curser is in the right field, just as they would have to before starting to type with their keyboard.

Keyboard wedge scanner kits come with a Y shaped cable that allows you to “wedge” the scanner between the keyboard and the computer.  Most scanners can draw enough power from the keyboard port to function, so an external power supply is usually not needed.  USB is nearly ubiquitous these days and a lot of new computers don’t even have a PS/2 keyboard port.  Just as USB has become the norm for keyboards, it’s also the norm for barcode scanners.

USB Interface

Barcode Scanner Interface: USB Port

As I just mentioned, USB is the norm for connection to a PC.  USB is the physical connection, with multiple communication protocol options.  USB ports provide sufficient power for most scanners and the scanner itself can emulate the communications protocols I just summarized, plus a third protocol.

USB Keyboard Emulation.  This is the default for most USB scanners.  It functions identically to the Keyboard Wedge Interface described above.

COM Port Emulation.  Using a software driver, USB scanners can be assigned a virtual COM Port.  This usually gives the user more flexibility in managing multiple devices using COM Port communication, but keep in mind that the software and hardware must be set to communicate on the same COM Port.

HID Barcode Scanner.  HID stands for Human Interface Device.  There are numerous devices which communicate in USB HID mode, including keyboards, mice and other input devices.  An HID keyboard (which is what USB Keyboard Emulation is) only allows one-way communication from the keyboard to the computer.  HID Barcode Scanner offers bi-directional communication, which opens up the potential uses by your software application.

Summary

The important thing to remember is that the right barcode scanner interface for you is the one that your data collection software supports.  Consult your documentation or contact your software vendor if you’re not sure.  Once you know how the software communicates with barcode scanners, we can help you find the right one for your needs.  Whether it’s corded or cordless, linear or 2D, fixed mount or handheld, we can help you find the right solution.  As always, we’re here to talk to you, answer your emails or chat online.  Contact us today.