Visual Basic With FactoryTalk View Studio Site Edition

[joelryan22]

Hello,
Im trying to learn how to use VBA with factorytalk view so i can later design displays using tags from PLCs and im having some trouble completing a basic exercise to increase my fundamental understanding.

I have 3 Tags
Dif_Test (Type: Analog, Data Source: Memory, Initial Value: 0)
Ex_Tag1 (Type: Analog, Data Source: Memory, Initial Value: 1)
Ex_Tag2 (Type: Analog, Data Source: Memory, Initial Value: 3)

I want Ex_Tag1 to be subtracted from Ex_Tag2 and stored into Dif_Test when i click on the Ex_Tag1 text. I have all 3 displayed on a display screen. When i click on Ex_Tag1 Nothing happens. Could anyone tell me my error in logic/code?

Option Explicit

Public mytagGroup As TagGroup
-------------------------------------------------------------------------------------------
Public Sub Display_Activate()

On Error GoTo Err_Handler

If mytagGroup Is Nothing Then
    Set mytagGroup = Application.CreateTagGroup(Me.AreaName)
    mytagGroup.Add "Ex_Tag1"
    mytagGroup.Add "Ex_Tag2"
    mytagGroup.Add "Dif_Test"
End If
    
Exit Sub

Err_Handler:

    LogDiagnosticsMessage "Error in DisplayAnimationStart", ftDiagSeverityError, ftDiagAudienceOperator
    
End Sub
-------------------------------------------------------------------------------------------
Public Sub Text21_Click()

Dim Ex_Tag1_A As Tag
Dim Ex_Tag2_A As Tag
Dim Dif_Test_A As Tag

Dim Ex_Tag1_Val As Integer
Dim Ex_Tag2_Val As Integer
Dim Dif_Test_Val As Integer

On Error GoTo Err_Handler

Set Ex_Tag1_A = mytagGroup.Item("Ex_Tag1")
Ex_Tag1_Val = Ex_Tag1_A.Value

Set Ex_Tag2_A = mytagGroup.Item("Ex_Tag2")
Ex_Tag2_Val = Ex_Tag2_A.Value

Set Dif_Test_A = mytagGroup.Item("Dif_Test_A")
Dif_Test_Val = Dif_Test_A.Value

mytagGroup.Item("Dif_Test").Value = (Ex_Tag2_Val - Ex_Tag1_Val)

Exit Sub

Err_Handler:

    LogDiagnosticsMessage "Error Determining Difference", ftDiagSeverityError, ftDiagAudienceOperator
    
End Sub

Again, Thanks for any help!

 

[crawler009]

If you step through your code, where does it jump to Err_Handler?

The only possible problem i see is with

Set Dif_Test_A = mytagGroup.Item("Dif_Test_A")

Do you have a tag named "Dif_Test_A"? If not it will go to the error handler.

Comment this line (and the next one) and try your code again.

 

[joelryan22]

If you step through your code, where does it jump to Err_Handler?

The only possible problem i see is with

Set Dif_Test_A = mytagGroup.Item("Dif_Test_A")

Do you have a tag named "Dif_Test_A"? If not it will go to the error handler.

Comment this line (and the next one) and try your code again.

Thanks Crawler,

I commented out my error handler instead and debugged my code using the built in debugger. I was mimicking an example from the FactoryTalk user manual and followed it a bit too close . The error was in the line you mentioned!