How to access the channel values?

[NiCoder]

I am new to DIAdem scripting language.  I have TDMS has one group and several channels with type all String.   How do I read the first 4 characters of each channel values and store it in new channel?  Sample data file attached.

I tried for statement in the Script Window

Ch("[1]/Result") = Ch("[1]/Frame") 

or 

Ch("[1]/Result") = Right(Ch("[1]/Frame", 3)

All gave me error ...

[Brad_Turpin]

Hi NiCoder,

You were on the right track, but you need to call that sort of expression using the ChnCalculate() command, which will take a reference to the whole channel array of values and apply the formula cell by cell through all the values in the channel array.  I'm including 3 version of about the same thing.  The first parses out the last 3 characters.  The second parses out all characters after the first character.  The third does the same as the second but creates a numeric result channel that you can use as an X axis on a graph.  The double-double-quote is the escape sequence in VBScript to denote one double quote character (ASCII=34) inside of a string constant.

Call ChnCalculate("Ch(""[1]/Result"") = Right(Ch(""[1]/Frame""), 3)")
Call ChnCalculate("Ch(""[1]/Result"") = Mid(Ch(""[1]/Frame""), 2)")
Call ChnCalculate("Ch(""[1]/NumericResult"") = CDbl(Mid(Ch(""[1]/Frame""), 2))")

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[NiCoder]

But it is automatic every cells in the same column at once.  I want to know how go through each single cell by DIAdem scripting. 

[Brad_Turpin · Accepted solution]

Hi NiCoder,

This is how you read and write individual channel values, but know that doing it value by value is much slower than doing them all with one ChnCalculate() call:

Set Group = Data.Root.ChannelGroups(1)
Set FrameChannel = Group.Channels("Frame")
Set ResultChannel = Group.Channels.Add("Result", DataTypeString)
iMax = FrameChannel.Size
FOR i = 1 TO iMax
  ResultChannel(i) = Right(FrameChannel(i), 3)
NEXT ' i

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[NiCoder]

How to combine all the following code into one call use ChnCalculate() function

Dim FrameStringSize

Set Group = Data.Root.ChannelGroups(1)
Set FrameChannel = Group.Channels("Frame")
Set ResultChannel = Group.Channels.Add("Result", DataTypeString)
iMax = FrameChannel.Size
FOR i = 1 TO iMax

   FrameStringSize = Len(FrameChannel(i))

   if (FrameStringSize = 7)
     ResultChannel(i) = Right(FrameChannel(i), 3)

   else if (FrameStringSize = 😎

     ResultChannel(i) = Right(FrameChannel(i), 4)

   End If
NEXT ' i

[Brad_Turpin]

Hi NiCoder,

None of the "Frame" values in the data set you posted have more than 4 characters, so this script you posted doesn't seem to apply to that data.  I had to tweak your syntax a bit to get it to run-- here it it:

Set Group = Data.Root.ChannelGroups(1)
Set FrameChannel = Group.Channels("Frame")
Set ResultChannel = Group.Channels.Add("Result", DataTypeString)
iMax = FrameChannel.Size
FOR i = 1 TO iMax
   FrameStringSize = Len(FrameChannel(i))
   if (FrameStringSize = 7) THEN
     ResultChannel(i) = Right(FrameChannel(i), 3)
   elseif (FrameStringSize = 8) THEN
     ResultChannel(i) = Right(FrameChannel(i), 4)
   ELSE
     ResultChannel(i) = FrameChannel(i)
   End If
NEXT ' i

 If you submit a script and data set that make sense to gether, I'll be happy to send you an example of using the IIF() function in the ChnCalculate() expression to change a script like that above into one line of code that executes much faster.

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[NiCoder]

Sorry, they should be column word_XX data in the same file.

[AndreasH_Ha]

Hello NICoder,

may be, I don't get the challenge here but wouldn't the Mid() function do the job ? From the scripts I saw, you try to copy all characters right of the  4th one, right ?

In that case the script could be something like :

Dim oGroup,oTextChannel

Data.Root.Clear

Set oGroup = Data.Root.ChannelGroups.Add("MyGroup")

Set oTextChannel = oGroup.Channels.Add("MyText",DataTypeChnString)

oTextChannel(1) = "Peter A"

oTextChannel(2) = "Paul BCD"

oTextChannel(3) = "Mary EFG"

oTextChannel(4) = "Jay"

' the following is the calculation itself. Omitting the second parameter of Mid() makes VBScript copying the "rest"

' Shorter text like "Jay" creates an empty entry which is probably what you want in this case

Call ChnCalculate("Ch(""LastCharacters"") = Mid(Ch(""MyText""),5)")