John, and the list.
There is a pretty good workaround for achieving this, I think it was
originally from Gary Johnson and was one of the example vi's in his first
book. Basically you create a buffer in a LV2 style global, and initialize
the buffer to either all NaN values (which don't show on a plot) or all to
the first data point. Then, as new points come in (in typical usage you use
two loops - acquire and write to the buffer in one loop, and read from the
buffer and display in another), you replace points in the buffer and rotate
the new points to the end. The end result is you replot your entire buffer
each time (not what you want) but it looks like you are just adding points
as new data comes in. It gives you an xy plot that acts like a strip chart,
with points being added in, and you have access to the "history" because
that is the data in the global. So, if it's asthetics you are after, this
helps. If raw speed is the goal, then maybe not. Maybe faking it with a
picture control is the better option there.
Hope this helps,
Alvin
Alvin W. Moore Jr.
Measurement Systems Programmer
Research, Development, and Engineering
Corning Cable Systems
Hickory, NC
John Brohan
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ca> cc:
Sent by: Subject: Redrawing XY Graphs
[EMAIL PROTECTED]
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05/11/2004 02:33 PM
Redrawing XY Graphs
Is there any technique to add new points to an XY graph without re-drawing
the whole thing? Dropping points does not seem to be an option in this
application.
Yours Sincerely
John
John Brohan National Instruments LabVIEW expert in Montreal
Traders Micro "We connect all sorts of things to computers"
317 Barberry Place DDO Montreal PQ Canada H9G 1V3 Tel (514)995-3749
[EMAIL PROTECTED] http://www.TradersMicro.com/Index.htm
