Elo TouchSystems 1525L - Manual (Page 90)

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SECTION 1. OVERVIEW
The MagTek Device (MTD) Drivers for Windows is a collection of individual drivers that
support a number of MagTek products. These drivers provide a uniform application interface for
controlling a wide range of MagTek devices. The drivers, combined with a device control
language, solve many of the difficulties application developers face when attempting to control
hardware devices. The difficulties mount when faced with the task of developing an application
that supports an entire product line of devices.
Part Numbers for the MTD are as follows:
Part Number
Windows Version Medium
30037385 All CD
99510030 9X/ME Internet* (MTD110-9x-ME)
99510031 NT (MTD110-NT)
99510032 2000/XP (MTD110-2K-XP)
*www.magtek.com
PROBLEMS WITH CONTROLLING DEVICES
The major problems with developing an application that supports an entire product line of
devices are as follows:
•
Each MagTek device has a unique set of commands. The commands usually perform
similar functions on a particular class of devices but either differ in syntax or have small
variations in their functionality. An application would have to implement a custom
mechanism to control each device it supported–much like DOS applications had to do to
support various printers.
•
Most MagTek devices communicate via data streams, not packets. This means that an
application receives data from the device one character at a time; it only receives partial
command responses. It would be the application’s responsibility to collect the incoming
data and parse it into individual responses.
•
Responses from MagTek devices are inherently asynchronous. When an application
sends a command that requires a response, the response from the device arrives (or
worse, begins to arrive) long after the command is sent. The application would have to
either poll the device until all of the response is collected or implement a callback
mechanism to collect and receive it.
•
Most MagTek devices maintain a communication protocol of some kind. In addition to
this, the protocols differ between devices. For example, some devices frame responses
with STX and ETX control characters and others simply use a CR or require a checksum
in the frame. To deal with this, an application would have to recognize and implement all
of the various protocols for the devices it supports.