How to address the energy parameter for an outlet?

[UkSub]

Been successfully running a rule as follows:

Select Trigger Events:
Energy level of socket changed

Actions to run:
Send GET to https://mywebsite/datareceive.php?device=%device%&parameter=power&value=%value%

the device btw is an "Aeon Outlet" and the parameter used is seen as "energy : 12.345"
As you'd expect, this transfers the value of the "energy reading" as %value% upon that value changing.
However, to be more correct, i wish to transfer that "value" on a timed interval but when i set the trigger to interval i lose the ability to obtain the energy value of the device.

Q. How can i do a time-based transfer of the energy parameter value for the device?
more specifically, how do i address the energy-value as a variable such as %socket.energy% (which btw fails)
thanks anyone

[FriedCheese2006]

Add a variable to the rule. Set your first action to set the variable to "device attribute." Use your new variable in the get.

[UkSub]

thank you VERY much @FriedCheese2006
Really helpful and solves many similar tasks i had yet to find solutions for.
Took a few minutes to find all the different sections but one of the best bits of learning to date for me,

[UkSub]

On a follow up note, it seems odd that you have to pass a parameter-value to a variable before you can make use of it.
Surely it would be more code-efficient to directly address the parameter-value?
That was my assumption of how i expected it to work up until now.

[FriedCheese2006]

Well, you only really need to in this instance because of the way the rule is triggered.