NCR RealScan 7802 Price Verifier User Guide
06/03
497-0425530 Release E
32 of 94
Software Developers Kit (SDK)
The CD-ROM shipped with RealScan 7802 contains the following items:
•
Unit Configuration
program for setting up the RealScan 7802 from the network.
Written in VisualBasic, the .exe, VB sources and an OCX are provided.
•
ServInstall
program for setting up the server to run slideshows.
•
User manuals and other useful documents in Acrobat (.pdf) format.
•
Source code for demo servers and some utilities. The sample programs demonstrate
communications with the RealScan 7802 via the ProductInfo and QFX protocols and
include ProductInfo and QFX servers. The VB sources and an OCX are provided for
the Unit Configuration program so it may be embedded in the host application. All
other programs are written in ANSI C and have been compiled and run without
modification under NT, linux, UNIX, and VMS. QFX is a faster, lower overhead
alternative to FTP and SMB and provides the added benefit of supporting graphic
files in any format.
•
A number of useful freeware and shareware utilities.
•
The RealScan 7802 requires images in either GIF or FIF (Fast Image Format), ¼ VGA
(320x240 pixel) format. NCR recommends the use of
ImageMagick
for image file
conversion from other formats into either GIF or uncompressed form.
ImageMagick
is a collection of tools and libraries for reading writing and manipulating images in
68 standard formats including TIFF, JPEG, PNG, PDF, PhotoCD and GIF.
Information on
ImageMagick
can be found at www.imagemagick.org.
ProductInfo Protocol Description
The RealScan 7802 has an embedded protocol engine that uses TCP/IP to send the UPC
barcode number from the price verifier to the host computer and return the price and
description information retrieved from the host computers’ database by its resident
application.
ProductInfo is a TCP based, bi-directional message–passing protocol that uses the same
format when moving data in either direction. In normal operation, the client opens a
connection for each request generated, usually a scanned barcode, and keeps it open
until the server instructs the client to close it. The client can also wait for the server to
open a socket thus permitting asynchronous operation.
The protocol also sends events marking a change of state (opening or closing) of any of
the four optional front panel switches. These events may be used by the host’s resident
application to control functions or modes within the application, for instance to change
language displayed when a switch is pressed.
An abstract system level diagram showing the relationship between the RealScan 7802,
the network and the host computer is shown at the beginning of this section. The API is
shown at both ends of the network for clarity. In practice the application to interface the
host computer server to the RealScan 7802 resides on the host computer.
In the interest of robustness, both ends accept any message whether defined or not,
invalid or unknown messages are simply discarded.
A maximum reasonable message
length may be used as a means to detect implementation bugs that could result in
loss of synchronization
. Such errors terminate the connection. If the client detects it, it
may send an error token following re–establishment of the connection in order to log the
error on the server. If the server is able to detect this condition, it can log it directly.
When the server receives a product query from the price verifier, it must respond even
Summary of Contents for RealScan 7802
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