Virtual properties

Virtual properties let users calculate indicators from existing properties. This article explains how to create them.

This module offers two features:

• Calculation of consumption 
• Calculation combining multiple properties 

Virtual properties are intented for Towers only. They are available from the Wattsense Console and the cloud (they are not available from the device itself meaning, they can't be used/redirected on gateways).

Calculation of consumption

For example : this kind of property can display a hourly, daily, weekly or monthly consumption of one building instead of the real time (index) consumption.

The value of a virtual property is updated as soon as a new value for the underlying property is received. This to see the current consumption alongside the consumption of the period before.

Consumption virtual properties can be applied to electric power data, water flow, gas flow …

They can be displayed in graphs, and used to create alarms.

Implementation in the console

In the Wattsense console, go to the Configuration/Virtual properties Tab, and click on the Create a virtual property button, then choose the option Calculation of consumption. 

Fill in the fields as follows :

1) Choose the option Calculation of consumption. 

2) Choose a name for the virtual property

3) Select an existing property of an equipement

4) Choose the computing interval (Hourly, Daily, Weekly, Monthly). See the note below to understand how the periods are taken into account.

5) Specify the scaling if necessary. This function can be useful if the value of the difference between to properties is not meaningful in the unit’s origin.

6) In this case above, it can be interesting to change also the original unit. 

7) Use Create another virtual property after this one chekbox to add a new property which will be prefilled by all the parameters of the previous one. 

Then use the button Save to finalize the adding.

The new property appears in the listing, then Save changes to send the information to the Wattsense Box.

Once the virtual properties are created, they all appear in the listing of the Virtual properties Tab.

From this page, you can modify, duplicate or delete the property.

You can only modify the name and the description of the property, the rest of the fields are not available for editing. If you want to change the interval for example, you will have to delete the property and recreate it.

Intervals calculation details 

Calculation rule : the virtual property is the last value of the period minus the first value of the period.

The virtual properties (consumption) have their timestamp at the beginning of the period as follows :

Hourly : example

Daily : example

Weekly : example

Monthly : example

Calculation combining multiple properties

This type of property allows calculations between properties using standard operands (*/+-). Example: calculating the average temperature across multiple sensors.

The value of a virtual property is updated as soon as a new value is received for the underlying properties.

Implementation in the console

In the Wattsense console, go to the Configuration/Virtual Properties tab and click the Create Virtual Property button, then choose the option Calculation combining multiple properties.

Fill in the fields as follows:

1) Choose the option Calculation combining multiple properties.

2) Choose a name for the virtual property.

3) Enter the calculation formula. You can use the shortcut @ followed by the property name if you know the exact name.

Alternatively, use the Insert Property button.

4) By default, the scaling of properties used in the formula is taken into account. However, you can disable this scaling if necessary.

5) Use the Test button to see the result.

6) Specify the unit of the virtual property.

Notes

• Removing a device whose property is used in a formula

If you remove a property used in a virtual property calculation, the virtual property will also be removed. This removal occurs in a cascading manner. Example:

Virtual Property 1 = (Property A + Property B + Property C) / 3

Virtual Property 2 = (Property D + Property E)

Virtual Property 3 = Virtual Property 1 + Virtual Property 2

Removing the sensor from Property A will remove Virtual Property 1. This will, in turn, remove Virtual Property 3.

• Updating these properties

These virtual properties are updated with the latest property values ​​present in the formula.

• Decimal numbers in the formula

Be sure to use a period . as the decimal separator (example : 0.001).

Virtual properties : Data analysis

The virtual properties are available in the live data tab as well as all the standard properties. They appear in the list in a special group (Virtual properties) like a new equipment.

They also can be displayed in graphs.

Moreover, virtual properties :

• can be exported and are available in the archive requests
• can be used to create alarm
• are available in the API and by extension in the data streams

Please contact us if you need any additional information : Wattsense Support