See: the PmaTrendGroup
For detailed description of creating trends see PROMOTIC Coursebook
- chapter Trends
Any number of variables can be trended (i.e. stored to disk and into the memory). These variables are stored as records with the following information: the store time, the system attribute, the value of the 1st variable, the value of the 2nd variable, etc. When halting and re-starting the application the storing continues in the existing file (in the database, in the binary file) at the point of the last stored record.
The stored data can be provided into the Internet/Intranet
by the configuration of the "Web server
" tab. It is necessary to to use the PmaWeb
object for providing the data into the Web. The client requiring data from this Web component is of the PmWebClient
type from the licence point of view.
The data (stored by this object) can be obtained by the GetData
methods. The GetData
method also allows to filter the data according to their values and it also provides the basic statistical functions (average, minimum, maximum, sum, count) that can be performed over all or only the filtered data.
It is possible to edit the stored data backward (overwrite originally stored values) by the SetValueByTime method.
object can dynamically change the location
of the data archive on the disk, or connect to existing data archive using the Open
object does not have to create the trends. It can also be switched to a "read only"
mode and offer the trends in files created by another systems. See: The PmaTrendGroup object in "Read only (new records cannot be written)" mode
In the PmaTrendGroup object, the #vars identifier is used in order to enable the access to the variables (of the PmVar type) defined on the "Data" tab. This identifier can be used e.g. in the Pm method, or for the PP data binding in the application and in panels. For example the method pMe.Pm("trend1/#vars/aaa") returns the aaa variable from the object named "trend1" that is of the PmaTrendGroup type.