Data transfer time or Image display time?

[Sean_usc]

I have question about the intensity graph display problem, which is similar to the question i posted several days ago. We want to use the intensity graph to display an array data(2Kbytes*33). we found the consuming time is around 10ms, which is too slow. So we did the following tests and tried to figure out the reason. The Labview code is included in the attachment.

Test 1: The output of a SubVI is not wired to the intensity graph in the same sequence frame. the consuming time is 0

Test 2: The output of a SubVI is wired to the intesity graph in the same sequence frame. the consuming time is 10ms.

Test 3: The SubVI and intensity graph are put in different frames of a sequence structure. we put a tick counter before and after the intensity graph. we figured out the time of displaying is around 1ms.

Based on those results, We draw the conclusions:
1 Display the intensity graph is not time consuming based on the test 3.
2 Transfering the data to intensity graph is time consuming.

Am I right? But why the transfering data is time-consuming? From computer RAM to Video card should be fast enough? any one could give me some ideas?

Thanks

[altenbach]

Your method is flawed. Displaying the graph is time consuming.

The graph update is done in the UI thread and the code will not wait until the graph is finished. Thus you falsely get the impression that the graph update is very fast. Right-click on the graph and select "advanced..synchronous display" and you will be able to see the real update time because now the code will wait until the graph is drawn.

For more details please read e.g. page 5 of Application Note 168.

I am also curious why you are now using extended precision for the graph. This cannot be very speed effective!