I would be able to help you better if you would provide what you already have for a script, but I'll make a couple of assumptions here:
I assume you are creating a block to read in the the ASCII data, something like this:
Dim Group : Set Group = Root.ChannelGroups.Add("MyGroup")
Dim Block : Set Block = File.GetStringBlock()
Dim NextValue : NextValue = File.GetNextStringValue(eString)
While (Not IsEmpty(NextValue)) 'IsEmpty is used to indicate that the end of the line has been reached.
Group.Channels.AddDirectAccessChannel(Block.Channels.Add(NextValue, eR64))
NextValue = File.GetNextStringValue(eString)
Wend
File.SkipLine 'Advance to the next line.
Block.Position = File.Position
Now what you want is for the block to stop reading when it comes to a blank space. There's no way to tell the block this directly, but you can tell the block how long it is, using the BlockLength property. In your case you probably want to figure this number out something like this:
Dim Length : Length = 0
NextValue = File.GetNextStringValue(eR64)
Dim NextValue2 : NextValue2 = File.GetNextStringValue(eR64)
While (Not IsNull(NextValue) And Not IsEmpty(NextValue2))
Length = Length + 1
File.SkipLine()
NextValue = File.GetNextStringValue(eR64)
NextValue2 = File.GetNextStringValue(eR64)
Wend
Block.BlockLength = Length
The reason for calling both IsNull and IsEmpty is that a NULL (aka NoValue) is always returned if the first value on the line is empty.
This code relies on their being a line that is totally empty. You could create an algorithm which uses the fact that you start finding lines with text in them after the block is finished. You could also improve this code by starting a new block and group here and reading these values in too.
I've also attached this code as a complete DataPlugin.
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For tips and tricks on creating VBScript DataPlugins go to http://dataplugins.blogspot.com.