Get Trace List VI

LabVIEW 2017 Datalogging and Supervisory Control Module Help

Edition Date: March 2017

Part Number: 371618K-01

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Owning Palette: Historical VIs

Requires: DSC Module

Retrieves a list of trace names from a Citadel database based on a particular pattern.

timeout specifies the maximum time, in seconds, that this VI waits for reading data from the Citadel database. The default is 30. A timeout value of less than or equal to 0 specifies no timeout, which means this VI waits indefinitely until this VI receives data from the Citadel database.
database URL specifies the computer name and the database name where the Citadel database resides. Enter the database URL in the format \\computer\database.

For example, if you have a copy of the LabVIEW Datalogging and Supervisory Control (DSC) Module and Citadel service installed on a computer named datalogger and the name of the database on that computer is data, you can access the data on datalogger from another computer by using the path \\datalogger\data. If you provide a database name only, this VI searches for the database on the local computer. If you do not wire database URL, this VI resolves the database URL from the Shared Variable Engine (SVE). If the SVE resolution fails, this VI reads data from the database associated with the default DSC Module process.
trace names specifies the traces. You can specify either Shared Variable references or existing traces for this input.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
get time range? retrieves a time range for trace list if get time range? is set to TRUE (default). If get time range? is FALSE, this VI does not return the first and last timestamps for the list of traces, which significantly increases the speed of the query when querying large databases.
use * as wildcard signals this VI to interpret the asterisk character as a wildcard character in any trace name given if use * as wildcard is TRUE. The wildcard matches any set of zero or more characters.
last timestamp specifies the date and time associated with the last data point retrieved from the historical database.
database URL out returns the computer name and the database name that specify where the Citadel database resides. The format is \\computer\database.
trace list returns the list of traces that have historical data logged. If a duplicate trace name exists in the trace names input, trace list returns only one instance of the trace name.
first timestamp is the date and time associated with the first data point retrieved from the historical database.
error out contains error information. This output provides standard error out functionality.

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