USB Barcode Scanner Application Integration Guide
This guide provides documentation, examples, software and source
code for the integration of hand-held USB and keyboard wedge barcode
scanners. Using these guidelines, hand held scanners may be easily integrated
with existing or custom applications as automation, input and verification
devices.
RS232 (serial port) barcode scanners have been commonly used as input
devices for several decades. RS232 scanners work very well in their
legacy applications, although their implementation is complex because
it requires that the application monitor and access the RS-232 API.
In addition, some new computer systems on the market today do not contain
RS232 ports and the serial port is a slow communication device.
USB and keyboard wedge
barcode scanners overcome these limitations by emulating the keyboard
so that anything scanned appears at the cursor as if it had been typed
in from the keyboard. The guidelines presented here offer several implementation
options.
Scanning data directly into a field is the easiest of all implementations.
The cursor is placed in the appropriate field that is to receive the
data from the scan and the trigger is pressed on the scanner. After
the trigger is pressed, the data appears at the cursor as if it had
been typed from the keyboard. This method may also be automated to include
functions such as tabs and
returns - even in web browsers and custom applications.
Program the Application to
Monitor for Specific Characters that Trigger an Operation
With this implementation, the cursor may be anywhere on the form.
The application is programmed to respond to a specific character that
is not frequently used. In this example, Visual Basic 6 is used to respond
to the tilde "~" character. However, applications may be programmed
to respond to any character that is not used for any other purpose in
the application.
To implement this example in Visual Basic 6, KeyPreview must be set
to True so the scanned data is evaluated:
Private Sub Form_Load()
Scanner_Activation_Form.KeyPreview = True
End Sub
Code is then placed in the application that will respond to the specific
character when scanned. ASCII 126 (the tilde key) is used to start the
process in this example. The tilde key may also be entered from the
keyboard to manually start the process.
Private Sub Form_KeyPress(KeyAscii As Integer)
If KeyAscii = 126 Then
KeyAscii = 0
ScannedData.Text = InputBox("Enter Data:")
End Ifbr>End Sub
After the data is scanned, the return function in the barcode chooses
the "OK" button after the data is automatically entered into the text
box. The character that triggers the process may either be encoded in
a barcode (as in the examples below) or added as a
preamble character in the scanner.
The trigger process may easily be tested with a barcode scanner and
the
sample application. If the
sample application example fails to execute, the
VB 6
runtime files may need to be installed. Scan the barcodes below
with the application open for an implementation example. The bar-codes
below encode a tilde at the beginning. Most modern scanners, such as
the
IDAutomation SC5 USB Barcode Scanner, automatically send a return
function by default after the data is scanned. Therefore, a return function
at the end of the barcode may not need to be encoded. The barcodes below
may be reproduced with any of IDAutomation's
barcode applications,
barcode font tools
and barcode components including
the free
online barcode image generator.
Code 128 barcode: Created by encoding
~TESTDATA into code 128. With Code 128 auto selected and ApplyTilde
enabled, a return function may be added to the end of the barcode by
encoding ~TESTDATA~013.
(This image was created with IDAutomation's
free on-line
barcode image generator)
Code 39 barcode: Created by encoding %STESTDATA
into Code 39. When using the
Code 39 Barcode
Font, *%STESTDATA* may be used. A return
function may be added to the end of the barcode by encoding
%STESTDATA$M.
(Note: Extended code 39 must be enabled in the scanner for the tilde
and return functions to work)
(This image was created with IDAutomation's
free on-line
barcode image generator)
Most modern scanners, such as the
IDAutomation SC5 USB Barcode Scanner, have the ability to encode
preamble characters. IDAutomation recommends using the GS character,
which is ASCII 29 for this operation. Normally, these characters are
not visible unless an application is used such as IDAutomation's
Barcode Scanner
ASCII String Decoder.
Program the application to respond to this character
as mentioned above, for example:
Private Sub Form_KeyPress(KeyAscii
As Integer)
If KeyAscii = 29 Then
KeyAscii = 0
ScannedData.Text = InputBox("Enter Data:")
End If
End Sub
How to Program a Barcode Scanner to Emulate Pressing a
Function Key
Very few Keyboard Wedge or USB Scanners can simulate pressing a function
key from the keyboard. However, if this operation is needed, the
IDAutomation SC5 USB Barcode Scanner can emulate all function keys
as well as other keys such PgUp, PgDn, Backspace, Tab, Enter, Esc, Insert,
Delete, Home and End. To activate this ability, simply enable "Function
Key Emulation Mode" by scanning the appropriate barcode in the manual.
Using this method, lower ASCII codes in a Code 128 barcode will simulate
pressing a key on the keyboard. For example, an ASCII 23 (0x17 in the
manual) digit encoded in a bar-code will send the same codes to a computer
as if the F7 function key was pressed. Because the scanner manual only
lists hexadecimal numbers, it may be necessary to refer to the
ASCII chart
for conversions.
IDAutomation's Free Barcode Scanner ASCII String Decoder is a software
application that decodes and reveals hidden, non-printable ASCII characters
and commands from keyboard emulation devices, such as
USB Barcode
Scanners. The application is compatible with Windows®
95 and greater, including Vista and Windows 7. Because certain commands
are not normally revealed when the barcode is scanned, this application
is useful in verifying commands like FS, RS, GS, and EOT when they are
encoded in barcodes. Symbols that include these characters include
UPS MaxiCode and
DOD UID.
This product is easy to use. After installing the application, ensure
the cursor is in the top text box. When the cursor is in this field,
any input from keyboard emulation devices is duplicated in the lower
text box. Information that is not normally visible is displayed between
greater-than and less-than signs according to its
ASCII function
or value.
Scanning may be automated to include functions such as tabs and returns
- even in web browsers and custom operating systems. Tabs and returns
may offer additional automation possibilities. For example, a single
barcode may enter data in one field, tab to another, enter more data
and choose the default button (a return) to perform a record lookup.
The functions may be programmed into the
barcode scanner or encoded directly in the barcode itself. Information
about encoding tabs and returns into barcodes is available in the
Code
39 FAQ and the
Code
128 FAQ.
Free support for hardware may be obtained by
contacting
the appropriate vendor of the scanner. Many other problems and solutions
are provided at IDAutomation's
support site and by searching resolved
public
help desk issues.
Priority
phone, email and help desk support is provided up to 30 days after
a purchase of a software product. Additional
priority
phone, email and help desk support may be obtained if the
Priority Support
and Upgrade Subscription is active for a software product.
IDAutomation offers many easy-to-use handheld and USB barcode scanners
including:
Barcode Printing Software Available
IDAutomation offers many products that print and/or create barcodes
including:
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