b - ASAM

eports from the workgroups
activity report from
ASAM GDI
(Generic Device Interface)
Solutions Guide 2007 SECTION TWO
Description
ASAM GDI was developed for the operating
system independent integration of
measurement and control devices into
applications. This standard consists of 4
layers. The higher layer depends on the lower
layer, the lower layer may be used
independent from the higher layer.
Transport Layer Extensions and
Communication Types (Layer 1) are
responsible for the data exchange between
the Platform Adapter and physical devices
connected at peripheral interfaces or between
the Platform Adapter and supporting software
systems. The Transport Layer Extension is an
operating system specific software, which has
to be developed for a standardized access to
all peripheral components. One extension
supports 1 to n Communication Types. For
most common interfaces RS232, IP4 and
USB, Transport Layer Extensions are available
on the market for Windows® and LINUX.
The Platform Adapter (Layer 2) provides a
standardized interface for the resources of the
operating system (cp. POSIX) and routes
communication between Device Drivers and
Transport Layer Extensions. The Platform
Adapter is an operating system specific
software. For Windows® and LINUX, Platform
Adapters are available on the market.
Device Drivers and Device Capability
Description (Layer 3): Device Drivers contain
device specific software for the
communication with devices via the Platform
Adapter. The standardized interface allows a
uniform access to different devices of any
kind. The Device Capability Description (DCD)
is a computer readable data sheet for the
devices handled by a Device Driver. It is a
class description and therefore it is valid for
one or many devices of the same kind. These
devices are called “virtual devices”, because
the view on a device may be defined by an
application and the Device Driver does the
mapping to the real devices. The resources of
a virtual device are again described with
classes, what allows an unlimited number of
equal resources, e.g. based on multiple
channels of real devices. ASAM GDI
developed so called Companion Standards,
which define the behaviour of devices for
special applications (Crash Test, Chassis
Dyno, Multi Data Acquisition and Emission
Bench). For such applications only one
standardized capability description (DCD) is
valid for all Device Drivers of different
manufacturers and the goal of the driver is to
make its devices fitting to the application.
Companion Standards make it possible, to
exchange drivers and devices of different
manufacturers with minor or no changes of an
application (Plug-and-Play). For the
integration of ECUs into GDI-based
measurement applications, a Companion
Standard for the use of MCD-3 based
systems was defined.
Coordinator and Parameter Instance
Description (Layer 4): The Coordinator
presents the resources of all used virtual
devices without a link to the devices itself. So
we get a pure application view on
measurement and control values. For the
mapping to devices, a coordinator reads a
Parameter Instance Description (PID), builds
up the resource interface and configures the
periphery accordingly (booting the system).
The PID is derived from DCDs and contains all
instances of devices and resources and the
values for parameters and attributes as
needed by a concrete application. Thus the
PID is a configuration file of an application
used by the Coordinator.
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