Installation manual

195
Glossary
Installin g and Upgrading ENVOX r Configuration Software on DEC VAX and DEC AXP Systems (Revision B — May 1998)
Setpoint (SP)
An input variable that contains the
desired value for a process variable.
Control loop algorithms compare the
process variable with the setpoint, to
determine an appropriate output.
Signal Value Analog (SVA)
The analog floating point portion of the
accumulator register in a controller FST.
Signal Valu e Discrete (SVD)
The discrete portion of the accumula tor
register in a controller FST.
Signal Value Percent (SVP)
The analog percentage portion of the
accumulator register in a controller FST.
Streams
A series of data fields separated by
commas (CDV format), representing a
configuration item. Streams begin with a
keyword called an identifying field. This
keyword identifies the stream type (for
example, UOC_GROUP). Streams end
with the keyword END.
Substreams
A series of data fields within a stream,
separated by commas (CDV format) that
begins with a keyword, and continues
until the next keyword.
Sybsystemprocs Database
Used in SYBASE SYSTEM 10. It is the
database which holds stored procedures
that were previously held in the master
database. It is created by SYBASE when
SYBASE is installed.
Tag
A unique identifying mnemonic or label
for a controller or point of a process
control system.
Target Device
Any system device that receives point
information, commonly a display device
that shows the information to an operator.
Tempdb Database
The database in which all temporary
tables are created. It is created by
SYBASE when SYBASE is installed.
Template
A pattern for valid relationships among
elements of a control strategy, defined
without specifying particular elements. A
template permits different specific
elements to use the relationships at
different times during the execution of the
control algorithm. The user establishes
templates as p art of system
configuration. [See Alias Template, DCD
Template, and Group Templa te.]
Transaction Log
A log file maintained by the dataserver of
all modifications to the database. As
additions, updates, and deletions are
performed on data, these changes are
written to the transaction log. Once the
changes have been accepted by the user
process and the transaction is complete,
the changes are applied to the
appropriate data file in the database. If
processing errors or system failures
occur, transactions which have not
properly comp leted are not applied to the
data file, and the memory cache copy of
the affected data is restored from the
data file. The transaction log is not the
Audit Trail log, but rather contains
SYBASE-only information.
Tuning
The adjustment of control terms or
parameter values to produce a desired
control effect.
Glossary