Trend annotations can be helpful when storing historical data or keeping data on a variety of unrelated or fast moving events. We’ve put together a tutorial on annotating trends in InduSoft Web Studio, should you require it.
Customers have asked us how they can apply trend annotation to their own applications. This article will explain how to do that.
The Trend Annotation Demo Application and Functionality
In the InduSoft Web Studio Help Manual (Technical Reference) there is a detailed section on setting up and using trend annotations in InduSoft Web Studio using a sample application as a guide. The original demo application version discussed in the Technical Reference Manual was built when InduSoft Web Studio 7.0 SP1 was the current version, and since then database functionality has been improved in subsequent versions to include Local Time, Local Time + Offset, and GMT.
When opening any converted project that was built prior to this change which uses MS Access database functionality, the database setting in the updated project will be the new default “GMT”, not the local time any more. Since the original TrendAnnotationID.app demo program was built using an MS Access database, it will not work as described in the Help Manual without modification. If you have downloaded an older version of this application, simply delete it and download it again.
We have just updated this application and changed the database time setting to “Local Time,” which MS Access does understand, and at the same time, given the app a facelift to make it appear more modern-looking. The app functionality however is unchanged and operates exactly as it was designed for the 7.0 SP1 version.
What happens within the application and scripts is described in detail in the Help Manual in the section: “Alarms, Events, and Trends >> Tend Control Object >> Display text- and image-based trend annotations in a trend control“, basically however, the application creates a new table in the database called “Trendnotes” and adds the appropriate columns needed to save annotation data to the database and display the annotation at the particular time index of the trend where the cursor is set and crosses the trend line. The whole topic in the Help Manual is too long and detailed to be reprinted here.
All Trend Annotations are saved in the database and can be recalled by displaying the particular history of the trend where the annotation was recorded. The functionality to change the font size and edit the Font was also built into the application. The rest of the runtime application operation is self-explanatory.
Here is a link to the video showing how to use the trend annotation application in InduSoft Web Studio.