Knowledge Base

The sample project is collecting power of solar panels on the roof of a building. We want to know the maximum power that can be expected according to the number of solar panels installed. Not only does the Application Architect automatically position symbols (see KB1122), but it is also able to automatically count the number of instantiated solar panels. Thus it is easy to create an expression which is multiplying the number of solar panel by the maximum power of one solar panel.

In Application Architect, the parameter definition:

The expression used: =ChildCount(_ctInst,”*”,1)
The parameter returns the number of template instances under the 1st level. In this case the evaluation mode is “Once” because the parameter is declared in the parent template (ROOF) of SolarPanel templates.

We add and use this parameter in ROOF template:

We can check that the value is correct in the instances tree:

So after synchronisation, the basic expression on variables will calculate the maximum power of all solar panels:

Thanks to all this, we have the right values in the mimic after the synchronization. Whether we add panels or remove them:

How to use the ChildCount function in an expression :

The argument eCountType determines which types of child items should be counted and on which criteria, child item’s instance name or child item’s template name.

Possible values are as follow:

The str argument is used to take into account child elements that match a pattern based on a regular expression:

• * Matches one or more characters
• ? Matches any single character
• # Matches any number
• [abc] Matches one character among {a; b; c}
• [!abc] Matches one character other than {a; b; c}
• [a-z] Matches one character between a and z
• [!a-z] Matches a character not between a and z

The argument num is the depth level for matching child items:

• If omitted (or -1): Count among child items with no depth-level limit.
• 0: Count items in the current instance and its embedded instances only (excluding any child item).
• Any other positive value n: Count among child items down to the n^th level.

For instance:

=Childcount(_ctInst_ByType,”Solar*”,-1)
Count the number of child instances without depth limit if the instances are templates whose name starts with Solar.

Download attachments: 

• Childcount_Project.zip