User manual

Computer Gateway User Manual 3-8 5/96
3.2.4
When its installation mode is Test, the data values returned to an ACP by a table-driven
data-access request are replaced by test values contained in the referenced Data Definition
Table.
During the time that an ACIDP is Inhibited by Operator action at a Universal Station, the
ACP will not be activated by the CG either by schedule or by PPS.
3.2.4 Data Definition Table Builder
The DDTs are prepared and stored separately from ACPs. The ACP specifies a DDT in the
data access fetch/store request. An ACP can use one or more tables (only one at a time),
but use of a DDT by more than one ACP can create file access problems in the host
processor.
The Definition Table Builder (DTB) creates five files for each DDT:
• External Point Names—This is separate from the user source file, and is used by the
Data Table Builder in rebuild operations.
• Internal Data Tables (Internal DDT)—These are the lists of converted point names that
are used to identify the point-parameter values to be accessed. Selection of which input
Internal DDTs are to reside in the CG is a Table Builder function.
• Transform File—This file contains all the user-defined values used in limit checking,
clamping, conversion calculations, data substitution, etc.
• Returned Value Status—This file contains the latest returned or stored data values; both
before and after conversion calculations values are included.
• Table Attributes—This file contains current status information on the DDT, including
the number of points of each data type it contains.
3.2.5 Definition Table Processor
The Definition Table Processor (DTP) acts only on current data requests (not on History).
For a current value-data fetch, the DTP processes the input value according to the rules and
destination specified in the DDT, then places the data in a table area specified by the ACP.
For a data store, the ACP output-request values are processed according to the rules
specified by the table parameters, then the processed data is sent to the CG. The DTP
optionally saves the values, both raw and processed, and value status in the Value/Status
table of the DDT.
3.2.6 Definition Table Viewer
The Definition Table Viewer (DTV) provides the engineer with the means of examining a
DDT that has been used by an ACP and processed by the DTP. The DTV is invoked and
values are displayed at a host-processor terminal. The parameters and values are gathered
into a temporary file that can be displayed or printed. Selected DDT entries such as limits
or substitution algorithms can be changed through the DTV (the DDT source file is
unchanged).