National Instruments BridgeVIEW How Do You Extract and View Data from Historical Log Files?

Chapter 6 Historical Data Logging and Extraction

BridgeVIEW User Manual 6-4 © National Instruments Corporation

How Do You Extract and View Data from Historical Log Files?

There are two methods for viewing historical data that has been logged to

disk. One method is to use the Historical Data VIs and the other is to use

the Historical Trend Viewer (HTV).

There are several VIs you can use in your HMI to manipulate data logged

in Citadel files. These VIs access disk files and do not require the

BridgeVIEW Engine to be running. You can use these VIs to browse files,

extract the information in a format that can be displayed in a Historical

Trend indicator, or export the data to a spreadsheet file format. There are

several examples in the Examples\HMI Examples\Historical Data

folder to illustrate this. The main VIs for getting historical data and

manipulating it are listed below. For complete information about these or

any other VIs, refer to Appendix A, HMI Function Reference.

• Decimate Historical Trend

• Decimate Historical Trends

• Get Historical Tag List

• Get Historical Trend Info

• Historical Trend Statistics

• Historical Trends to Spreadsheet

• Historical Trends to Spreadsheet File

• Read Historical Trend

• Read Historical Trends

The following illustration shows a VI for viewing historical data files

anywhere in the system.