Write Trace VI

LabVIEW 2017 Datalogging and Supervisory Control Module Help

Edition Date: March 2017

Part Number: 371618K-01

»View Product Info
Download Help (Windows Only)

Owning Palette: Database Writing VIs

Requires: DSC Module

Writes a single data point to a Citadel trace.

You must select the polymorphic instance of this VI that matches the type of the Open Trace VI you used to create the input refnum.

This VI returns an error if you try to write a point with a timestamp that is earlier than the timestamp of the last point written to the trace.

Example

Use the pull-down menu to select an instance of this VI.

Write Trace (Numeric)

trace ref is the reference for the trace being written. Only references created by the Open Trace (Numeric) VI are valid.
value is the value to write to the database.
timestamp is the timestamp associated with value. Leave this input unwired to associate the current time with this value.
Note  The Read Trace VI returns data breaks as a default value with a 0 timestamp. If you want to use the Read Trace and Write Trace VIs to copy Citadel data, do not wire the output of the Read Trace VI directly to the input of the Write Trace VI. Instead, detect any 0 timestamps in the Read Trace VI output and use the Write Trace Break VI to log data breaks correctly. Consider using the Archive Traces VI to copy Citadel data more efficiently.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
trace ref out is the same value as trace reference.
error out contains error information. This output provides standard error out functionality.

Write Trace (Logical)

trace ref is the reference for the trace being written. Only references created by the Open Trace (Logical) VI are valid.
value is the value to write to the database.
timestamp is the timestamp associated with value. Leave this input unwired to associate the current time with this value.
Note  The Read Trace VI returns data breaks as a default value with a 0 timestamp. If you want to use the Read Trace and Write Trace VIs to copy Citadel data, do not wire the output of the Read Trace VI directly to the input of the Write Trace VI. Instead, detect any 0 timestamps in the Read Trace VI output and use the Write Trace Break VI to log data breaks correctly. Consider using the Archive Traces VI to copy Citadel data more efficiently.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
trace ref out is the same value as trace reference.
error out contains error information. This output provides standard error out functionality.

Write Trace (String)

trace ref is the reference for the trace being written. Only references created by the Open Trace (String) VI are valid.
value is the value to write to the database.
timestamp is the timestamp associated with value. Leave this input unwired to associate the current time with this value.
Note  The Read Trace VI returns data breaks as a default value with a 0 timestamp. If you want to use the Read Trace and Write Trace VIs to copy Citadel data, do not wire the output of the Read Trace VI directly to the input of the Write Trace VI. Instead, detect any 0 timestamps in the Read Trace VI output and use the Write Trace Break VI to log data breaks correctly. Consider using the Archive Traces VI to copy Citadel data more efficiently.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
trace ref out is the same value as trace reference.
error out contains error information. This output provides standard error out functionality.

Write Trace (Bit Array)

trace ref is the reference for the trace being written. Only references created by the Open Trace (Bit Array) VI are valid.
value is the value to write to the database.
timestamp is the timestamp associated with value. Leave this input unwired to associate the current time with this value.
Note  The Read Trace VI returns data breaks as a default value with a 0 timestamp. If you want to use the Read Trace and Write Trace VIs to copy Citadel data, do not wire the output of the Read Trace VI directly to the input of the Write Trace VI. Instead, detect any 0 timestamps in the Read Trace VI output and use the Write Trace Break VI to log data breaks correctly. Consider using the Archive Traces VI to copy Citadel data more efficiently.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
trace ref out is the same value as trace reference.
error out contains error information. This output provides standard error out functionality.

Write Trace (Variant)

trace ref is the reference for the trace being written. Only references created by the Open Trace (Variant) VI are valid.
value is the value to write to the database.
timestamp is the timestamp associated with value. Leave this input unwired to associate the current time with this value.
Note  The Read Trace VI returns data breaks as a default value with a 0 timestamp. If you want to use the Read Trace and Write Trace VIs to copy Citadel data, do not wire the output of the Read Trace VI directly to the input of the Write Trace VI. Instead, detect any 0 timestamps in the Read Trace VI output and use the Write Trace Break VI to log data breaks correctly. Consider using the Archive Traces VI to copy Citadel data more efficiently.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
trace ref out is the same value as trace reference.
error out contains error information. This output provides standard error out functionality.

Example

Refer to the Database Direct Write Demo.lvproj in the labview\examples\lvdsc\Data and Alarm Historical Logging\Database Direct Write Demo directory for an example of using the Write Trace VI.

WAS THIS ARTICLE HELPFUL?

Not Helpful