Q:

Read a Date and time string in ParcView and Subtract to find Difference

I am very new to programming and have done most my coding in VBA. That being said still very amateur.
I'll explain the best I know how my scenario, some info may be self-explanatory but not to me. I'm working with a Trending software (PARCView that reads from a PLC and HMI system to display data. The current PLC tags do not give all the data that I need so this PARCview software allows me to create new tags in order to manipulate data and display trends, efficiencies, etc. that I may want.
It allows me to import and export XML script to do the Calculated tag, but using a VBA format would work best for me so I can understand better. I am able to figure out how to do simple calculations like multiples, dividing of data from a single tag, but now I am struggling to do more complex manipulations.
I would like to find the time in hrs. between two dates and times given. The dates and times are pulled as a string from another software called MiniMint. They are received in the format m/d/yyyy hh:mm:ss. The date does not use 0's as place holders so it can be seen as mm/d/yyyy or mm/dd/yyyy as well. I do not understand how to take this string of "text" and read it correctly as numbers to do the calculations I would like.
The two tags I would like to subtract are called FL4 End Run Time and FL4 Scheduled Start and both are received in the format listed above.
So I don't know where to start and appreciate the help greatly!

A:

I'm not sure about the tags, PARCView, PLC and HMI, but in VBA, I would use the following to convert a string date like that into a date object:
Function String2Date(inString As String) As Date

    Dim sp() as String
    Dim month as Integer, day as Integer, year as Integer

    sp() = Split(inString, "/")    'splits the string into an array, using /
    month = CInt(sp(0))  'CInt forces a conversion to integer from string, just in case
    day = CInt(sp(1))
    year = CInt(sp(2))

    String2Date = DateSerial(year, month, day)    'date serial returns a date from integer year, month, day arguments
End Function

