Basic expressions:
1 – IF
2 – For
3 – While
4 – Goto
(To understand how to introduce the script in the SCADA software: Script – Introduction – Step 1)
1 – IF
If expression indicates a decision based on condition.
If <expression> Then
…
End If
Example 1 (Tag1 as numeric tag and message1 as text tag):
If ( Tag1 = 2 ) Then
message1 = “Alarm 2”
End If
Example 2 (Tag1 as numeric tag and response as text tag):
If Not ( response = “ERROR” ) Then
Tag1 = 3
End If
Example3 (Else and ElseIf expression)
If ( Tag1 = 1 ) Then
Tag2 = 1
Tag3 = 3
Tag4 = 7
ElseIf ( Tag1 = 2 ) Then
Tag2 = 7
Tag3 = 1
Tag4 = 3
Else
Tag2 = 1
Tag3 = 7
Tag4 = 1
End If
Important: expression ElseIf demands an Else at the final, even if it is empty.
2 – For
For command makes a loop variable go from one value to another.
For <variable> = <inicial> to <final>
…
Next
Example:
For i = 1 to 10
tag(“Tag”+CStr(i)) = i
Next
Important: This expression should only be used for quick operations. In slow cases, instead of For, a loop must be made by a global variable adding to each OnGroup or OnAfterUpdate execution.
3 – While
Expression While performs a loop while a condition is true
While <condition>
…
WEnd
Example:
i = 1
While i <= 10
tag(“Tag”+CStr(i)) = i
i = i + 1
Next
Important: This expression should only be used for quick operations. In slow cases, instead of While, a loop must be made by a global variable adding to each OnGroup or OnAfterUpdate execution.
4 – GoTo
Command GoTo leads the execution of the script to a label position.
Goto labelname
….
labelname:
…