Compsee Apex III, Техническое справочное руководство

Страница: 95 / 168

Apex PDT Technical Reference Manual 6 Utility Programs
COAM30002 Rev. 2.00 8/13/02
6-23
Wedge Mode
The default mode when loading the driver is Wedge Mode. In
Wedge Mode, decoded symbols are placed into the standard
keyboard buffer and standard C calls are used to remove them (e.g.
getch(), getche(), etc.).
Factors affecting the use of Wedge Mode include the following:
q
Wedge Mode is limited by the size of the keyboard buffer,
which by default (in all DOS based computers) is limited to 15
characters. The buffer size is limited to the size of the
keyboard buffer.
q
The number of decoded characters is unknown. If decoded
data will not fit into the keyboard buffer, the data is truncated.
q
Applications must constantly read the keyboard buffer and
remove keystrokes to prevent data errors while in wedge mode.
q
The data may require termination with a carriage return
<ENT>, thereby reducing the size of the data characters that
will fit into the buffer by one.
q
In order to know the decoded symbology type, the symbology
type identifier must be turned-on thereby reducing the number
of data characters that will fit into the buffer.
q The application program can NOT recognize whether the data
came from the scanner or the keyboard.
q
The functions gets() and scanf() are NOT recommended for
removing keys since both require carriage returns.
q The functions gets() and scanf() are incompatible with the
Apex PDT Bar Code Driver utility program.
Use of the buffered mode of operation (application supplied
external buffer) is recommended, since this non-wedge mode
provides much finer control and reporting of the decoded symbol
information.
Additional BCDRIVER Resources
Additional Bar Code Driver programming resources are available to
the Apex PDT developer through the use of the Apex Programming
Resource (APR). Refer to the Apex Programming Resource section
of this manual for detailed information.