Instrument I/O Assistant returning delayed/slow response?

[slnovak]

Hi there,

I'm somewhat new to LabVIEW 7.1 - I'm trying to make a simple program that reads and parses data over a serial line then plots it.

I created a small program which connects the output from the IIOA to waveform charts.  I've read that the waveform charts plot the data points when the data is received, but when running the program, the chart updates with a new data point at 1Hz, yet my data is being sent at ~10Hz.

I opened the Front Panel for the IIOA and ran just that .vi, and still, the data updates very slowly.

Can someone offer me some insight regarding this problem?



Thank you,
Stefan

[JasonSmith]

Hi Stefan,

If you have opened the front panel for the Instrument I/O Assistant, and the data still updates slowly, then it is likely that your instrument is taking longer than you think to respond?  I would recommend that you run NI-SPY while you are performing your acquisition.  In NI-SPY, you can double click on any of the driver calls and see how long the command took to execute.  This will allow you to determine whether there is a long delay inbetween two commands, or if the read command is taking a long time to complete.  I suspect that you will see that the read command is waiting a while before it actually receives the data and is able to return.

Let us know what you are able to find with NI-SPY, or if you have any more questions.

Jason S.
Applications Engineer
National Instruments