x-axis with negative time values

[RainerB]

In a previous version of Measurement Studio (VB6) I used the wavegraph to plot xy data with a negative timestamp (x axis). This was very usefull to show values before and after a trigger point and to set the timevalue of the trigger point to zero.

Now I try to convert these program to a .NET assembly but I haven't found a way to show negative values in time formated x axis labels. If I switch the Label format to DateTime an ArgumentOutOfRangeException is thrown.  But it is very urgend to show the time difference between the plotted values and the trigger in a time format.

What can I do to get the same solution like before?

Rainer

[PeterAdelhardt]

Hi Rainer,

Kristen Cippant from our team in Austin provided an example on how to do this in our internal forums. I attached the project. Here is what she added as comments:

"So, what I had to do was inherit from FormatStringMode and create my own string mode that I called NegativeDateTimeFormatString.  I had set the mode to be Numeric instead of DateTime to avoid all the ArgumentOutOfRange exceptions.  I overrode the FormatDouble function so that it formats the data as a DateTime then converts it to a string to be displayed on the graph.  I get around the exceptions here by getting the absolute value of the number first if it is negative, converting to DateTime, then to String, and then appending the '-' back on the front."

I hope you can use this as a replacement for your current solution. 

Best regards,

Peter

[RainerB]

Hi Peter,

Thanx for your (and Kirstens) help, the solution works very good.

That's what I was looking for.

Thank you

Rainer

[Per Helge]

I have been looking for this for a while. Is it possible to do this using WaveFormGraph as well? Not just a scatter Graph? In WaveFormGraph, I have to use either DateTime (which can not be set negative) or samples on the x-axis.

I have been working on this project for a while så it would be a lot of work to leave WaveFormGraph behind now. 

Waiting eagerly for response.

-per helge