How can I add values of a device every time they change ?

[mikee123]

I have a device showing kW Hours. This resets sometimes which makes it useless for my application. So I have to create a script, which grabs the value, and then when it goes to 0 and starts counting again adds it to the value it had before it has been zeroed again. (I am thinking maybe take the difference every time the value changes and add it to a virtual device. Would that work ?)
I will need the daily total kW Hour number at 21.55 every day for another calculation. At or after midnight I want to reset it to 0 again, and start the process of adding up again.

Not easy I think but I hope that can be done ?

[Uncle Michael]

How often does the value update?

I'm thinking you could create two virtual devices. One would track the kW hour device, the other would capture the cumulative value. Your script would run every time the kW hour device value changes.

If the new kW hour value is greater than the value of the tracking virtual device, then that difference is added to the value of the cumulative virtual device. If the kW hour value is less than the tracking virtual device, then assume the kW hour device has reset to zero and just add the value of the kW hour device to the cumulative virtual device. In either case, assign the new value of the kW hour device to the tracking device before exiting the script.

Reset the cumulative device to zero at the appropriate time, either with the script or a separate event.

[mikee123]

Yes I think that would work. When I have time tomorrow I'll have a go try to put that into a script. If it doesn't work or if I get stuck I'll be back for more help...

The updates are linked to my PV panel production, so they can update a couple of times a minute when the sun is shining

[mikee123]

How often does the value update?

I'm thinking you could create two virtual devices. One would track the kW hour device, the other would capture the cumulative value. Your script would run every time the kW hour device value changes.

If the new kW hour value is greater than the value of the tracking virtual device, then that difference is added to the value of the cumulative virtual device. If the kW hour value is less than the tracking virtual device, then assume the kW hour device has reset to zero and just add the value of the kW hour device to the cumulative virtual device. In either case, assign the new value of the kW hour device to the tracking device before exiting the script.

Reset the cumulative device to zero at the appropriate time, either with the script or a separate event.

Ok I think using your idea I have a solution. Instead of saving in a virtual device, I am writing this to an ini file I use to track other variables too. I am setting a virtual device as well for display purposes (ref 966).
This is what I have come up with:

Const IniFile As String = "MyVariables.ini"

Sub Main(ByVal Parms As Object)

        Dim HWkWH As String
        HWkWH = hs.DeviceValueEx(960)
        Dim HWcumulative = hs.GetINISetting("MyVariables", "HWcumulative", "999", IniFile)


      If HWkWH > HWcumulative
   
         HWcumulative = (HWkWH - HWcumulative) + HWcumulative

      End If

     hs.SaveINISetting("MyVariables", "HWcumulative",HWcumulative, IniFile)
     hs.SetDeviceString(966,HWcumulative,True)
     hs.SetDeviceValuebyref(966,HWcumulative,True)

    End Sub

[Uncle Michael]

I may be missing something in your script, but I think you need to track two numbers (using an ini file is a good method). This line:

HWcumulative = (HWkWH - HWcumulative) + HWcumulative

is equivalent to this, I think: HWcumulative = HWkWH
That is, it looks like your ini value will always reflect the kW hour device.

I do not understand how you handle the case when your kW hour value is reset to zero. I think you need to track both the value of the kW hour device and the cumulative separately so that when the device resets, you do not lose the previous cumulative value.

[mikee123]

I see what you mean. Ok back to the drawing board. Have to rethink my logic.

[mikee123]

I might have it

Const IniFile As String = "MyVariables.ini"

Sub Main(ByVal Parms As Object)


        Dim HWkWH As String
        HWkWH = hs.DeviceValueEx(976)
        Dim HWcumulative = hs.GetINISetting("MyVariables", "HWcumulative", "999", IniFile)


      If HWkWH > HWcumulative
   
         HWcumulative = HWkWH

      End If

      If HWkWH < HWcumulative
   
         HWcumulative = HWcumulative + HWkWH

      End If



     hs.SaveINISetting("MyVariables", "HWcumulative",HWcumulative, IniFile)
     hs.SetDeviceString(966,HWcumulative,True)
     hs.SetDeviceValuebyref(966,HWcumulative,True)


End Sub

[Uncle Michael]

I think this segment will result in compounding the results:

If HWkWH < HWcumulative
HWcumulative = HWcumulative + HWkWH
End If

To get the result you want, you will need to store the total before the reset in a separate variable (I'll call it HWstore) that does not change each time the script runs. To do that, I'd suggest that you initially assign HWstore a value of zero, then when the kW hour value resets, transfer the previous vale of HWcumulative to HWstore.

Then, your computation would look like:

HWcumulative = HWstore + HWkWH (nice palindrome, by the way)

A problem still remains, though. How will the script know that the kW hour value has reset? Because, once it resets, HWkWH will always be less than HWcumulative. The only way I can see is to store the previous value of HWkWH and compare it to the latest value each time the script runs. If you do that, then I think that difference can simply be added to HWcumulative and you won't need HWstore. You'll only need a special case for calculating the difference when the value resets, which I think is to assign the value of zero to the previous value of HWkWH.

So, in pseudo code, something like this:

Retrieve HWkWHold and HWcumulative from the ini file

If HWkWH < HWkWHold Then HWkWHold = 0

HWcumulative = HWcumulative + HWkWH - HWkWHold

HWkWHold = HWkWH

store HWkWHold and HWcumulative back into the ini file

[mikee123]

Cant quite get my head around this. Below should work, until after a reset. The first reset still works, but then it wont work.

Const IniFile As String = "MyVariables.ini"

Sub Main(ByVal Parms As Object)


        Dim HWkWH As String
        Dim HWstore As String
        Dim HWkWHold As String
        HWkWH = hs.DeviceValueEx(976)
        Dim HWcumulative = hs.GetINISetting("MyVariables", "HWcumulative", "999", IniFile)
        Dim HWkWHold = hs.GetINISetting("MyVariables", "HWkWHold", "999", IniFile)


      If HWkWH < HWkWHold
   
         HWcumulative = HWcumulative + HWkWH
         HWkWHold = HWkWH

      Else

         HWcumulative = HWkWH
         HWkWHold = HWcumulative

      End If


     hs.SaveINISetting("MyVariables", "HWcumulative",HWcumulative, IniFile)
     hs.SaveINISetting("MyVariables", "HWkWHold",HWkWHold, IniFile)
     hs.SetDeviceString(966,HWcumulative,True)
     hs.SetDeviceValuebyref(966,HWcumulative,True)


End Sub

[Uncle Michael]

Cant quite get my head around this. Below should work, until after a reset. The first reset still works, but then it wont work.

Two observations:

1. HWcumulative = HWcumulative + HWkWH will only work once - when the value has just reset. After that, you will be compounding the accounting of new power use. You need to add the incremental kWH (HWkWH - HWkWHold, where HWkWHold is the value of HWkWH on the previous run). HWkWH is the total accumulated since the last reset.

2. If you set HWkWHold = HWcumulative after a reset, then HWkWH < HWkWHold will be true again. So it looks like you will be jumping between the two alternatives in your If statement every other time the script is called after a reset.

[mikee123]

Exactly. I noticed that but couldnt get my head around it. Now its getting late and I havent got the concentration any more. Maybe tomorrow.

[Uncle Michael]

Try something like this:

Const IniFile As String = "MyVariables.ini"

Sub Main(ByVal Parms As Object)

        Dim HWkWH As Double   ' I don't understand why this is defined as a string, when you are assigning a number to it.  I'm surprised you aren't getting an error.
        HWkWH = hs.DeviceValueEx(976)
        Dim HWcumulative As Double = hs.DeviceValueEx(966)
        Dim HWkWHold = hs.GetINISetting("MyVariables", "HWkWHold", "999", IniFile)

    If HWkWH < HWkWHold Then HWkWHold = 0     'Assume the value reset to zero
    HWcumulative = HWcumulative + HWkWH - HWkWHold
    HWkWHold = HWkWH

     hs.SaveINISetting("MyVariables", "HWkWHold", HWkWHold, IniFile)
     hs.SetDeviceString(966,CStr(HWcumulative),True)
     hs.SetDeviceValuebyref(966,HWcumulative,True)    

End Sub