Appendix E Glossary of Terms
155
Database SQL
Query
A Database SQL Query (or SQL Query for short) is
interpreted dynamically at runtime. The SQL Text can be
modified at runtime, enabling different Queries to be run
for varying situations however, the SQL Text has to be
compiled on the fly every time it is executed and
consequently is less efficient than a Server Query.
DBCS DBCS stands for Double Byte Character Set and is a
Microsoft extension of ASCII which uses 2 bytes (16 bits)
to define character codes. With this larger range it can
include accented characters, extended ASCII characters,
Nordic characters and symbols.
DCOM DCOM is a distributed version of COM that allows
components on different PCs to interact over a network.
DDE Dynamic Data Exchange. A channel through which
correctly prepared programs can actively exchange data
and controls other applications within Microsoft
Windows. DDE technology was notoriously unstable and
was replaced with OLE technology.
See also Item, Server, server application and Topic.
Development
Environment
SCADA applications are created and tested using the
development environment within CX-Supervisor. On
completion, the finished application can be delivered as a
final customer application to be run by the run-time
environment.
DLL Dynamic Link Library. A program file that although
cannot be run stand-alone as an executable, can be
utilised by one or more applications or programs as a
common service. DLL files have a *.DLL extension.
DLL's comprise a number of stand-alone functions. In
CX-Supervisor, a DLL containing icons can be accessed
to represent the display part of an OLE object. One such
DLL, 'MORICONS.DLL', is provided in the standard
Microsoft Windows installation.
Download A recipe is downloaded during runtime. This process
involves identifying the appropriate recipe and executing
the validation code, if any exists. The download is
complete when each ingredient has set its point to the
target value.
Executable A file that contains programs or commands of an
application that can be executed by a user or another
application. Executable files have a *.EXE file extension.
CX-Supervisor provides two executable files, one for the
development environment (CXSUPERVISORDEV.EXE),
and one for the run-time environment (SCS.EXE).
Expressions In the CX-Supervisor script language, expressions are a
construct for computing a value from one or more
operands. For instance, in the example "lift =
height + rate", the expression is "height + rate"
where the result yielded from the expression is used for
the value of "lift".
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