Data Acquisition Processors
The following diagram, in the style of a simplified UML object
diagram, shows the elements of a complete software system for data
acquisition and control applications. Details about the elements
are given below. Use it to help determine the DAP software
your application requires.
Data Acquisition Processor (DAP) software is supported at
three levels, each one including all
features of the preceding level. All software levels
support all DAP models.
- DAPtools Basic (included with each system purchased)
Provides everything you need to run DAP applications.
- DAPtools Standard
Adds everything you need to develop new host system
applications using DAP boards.
- DAPtools Professional
Adds everything you need to develop networked applications and real-time embedded processing
for your DAP systems.
DAPstudio software is optional, but
helpful for configuring DAP processing. In some cases, DAPstudio
has everything necessary for a complete application environment on
the host system. A copy is included with each DAPtools Professional
Application software can be an application you develop,
a third-party application, or your favorite "data acquisition
environment". Though not mandatory, most developers use
DAPstudio software to help configure the Data Acquisition
Processor. Some applications use DAPstudio in both roles, for
configuration and for the primary application.
A licensed copy
DAPstudio software is included with
DAPtools Professional. A demo version of DAPstudio – that you can upgrade
to a fully licensed version – is provided in DAPtools Basic and DAPtools Standard.
Input, output, and processing on the Data Acquisition
Processor are set up using a
script file, sometimes called a "DAPL file"
because the script will be interpreted and applied by the DAPL system. The same script file will work for any DAP model – as
long as you use only features that the board supports. You can
prepare the configuration script file with any text editor, or you
can let DAPstudio software generate it for you. If you are using
DAPstudio software as your application environment, you do not need
to save a separate script file.
All host software interactions with a Data
Acquisition Processor, both for configuration or run-time
activity, work through functions provided by the DAPIO32.DLL.
There is no direct interaction with hardware or hardware drivers.
If you are developing your own software applications, you need the
language-specific DAPIO bindings provided by the DAPtools Standard
or DAPtools Professional packages.
Your data acquisition applications can access multiple Data
Acquisition Processors. Whether located in the local host or a
remote station, all DAP boards are accessed through services
of the DAPIO interface. Applications might establish network links
for other purposes, but DAP boards do not connect in that
manner. If no DAP is installed at the local station to provide
the DAPIO interface, you need to install the special DAPcell Client configuration from DAPtools Professional.
DAPcell is the central hub for DAP activity on each host system.
DAPcell services are configured through the Data Acquisition
control panel application installed by every DAPtools version.
There are four server versions, providing different degrees of access.
- DAPcell Basic Server – in DAPtools Basic
Supports local host access only – the DAP board cannot be seen
across the local network.
- DAPcell Local Server – in DAPtools Standard
Adds features for direct disk feeds and
data logging, for highly optimized transfers without intervention by
application software – but still no network visibility.
- DAPcell Server – in DAPtools Professional
Provides full network services, allowing a DAP board to be visible
over a local network.
- DAPcell Client – in DAPtools Professional
Omits server features, for the special
situation that no DAP is available in the local station.
Data buffering services and device driver functions supported by
DAPcell are always available and always isolated. There is no direct
access to these functions from application software.
The DAPcell services also manage the host side of data transfers
across the bus to the local DAP boards. The DAPL system, running
on the Data Acquisition Processor boards, manages the data transfers
and processing on that side.
All of the DAPtools packages provide DAPL system software
for all DAP models. All versions of the DAPcell services will load
the DAPL system code to the DAP at system boot time. If you have
registered any additional processing software modules with the
DAPcell services, these also will be merged into the DAPL system
automatically. For example, the DAPtools Standard and Professional
CDs provides the DAPL IIR Filtering Module, which adds processing
for the most common IIR digital filter types.
There is no direct user interaction with devices on the
Data Acquisition Processor. The hardware-driven, time-critical
processing and software-based processing (under control of a
task scheduler) perform all of the input, output, and
processing tasks defined in the configuration script. While
this occurs, the DAPL system continues to transfer data and
messages, as specified by the configuration script and
interactive requests through the DAPIO interface.
Time-critical processing such as safety monitoring or
feedback control should not involve the delays and uncertainties
of data transfers to the host – and then back again.
These activities can be moved entirely onto the DAP, leaving
the host free to monitor progress and analyze results.
On the DAP board, numerically intensive processing to clean up
or reduce raw data can be performed in parallel with data
collection. Commands that you develop to run in the DAPL
embedded environment will require the C++ bindings provided by
the Developer's Toolkit for DAPL, which
is available only with the purchase of DAPtools Professional.