[cRIO] question about tutorial

[ecw]

Hello, I am following the tutorial to work with cRIO-9074 with LabVIEW 8.6. Page 11 shows a sinewave with about 1000 samples. When I run the code, I get this instead.  The number of samples is still around 1000, the period is the same. But the resolution is different. Is there something setting I need to change?

- Thank you. 

[James_McN]

Hi,

What you are seeing is not a resolution issue but a timing issue.  If the host VI polls the network variable too frequently then you will get the same value for successive samples.  I would suggest changing the timing constant on the host VI to a control and have a play with that and see what effect this has on your outputs.

Don't hestitate to ask if you have any more questions.

Regards,

[ecw]

Hi,

According to the two vi, the host is reading every 10 ms and the target is creating a value every 10 ms. So I would expect that each sample would be different. On the plot, I thought there were supposed to be 1023 samples. But it seems that many samples were the same, thus the staircase shape.

Also, currently I have both LabVIEW 8.5 and LabVIEW 8.6 installed on the same computer. When I create a new project, I could select the device in 8.6, but not in 8.5. LabVIEW 8.5 could not find the device. I installed the 8.5.1 versions of the software on cRIO and tried again, but LabVIEW 8.5 still didn't detect it. When I use 8.6, 8.6 detects the device, and tells me that cRIO has the 8.5 software and asks me to update its software. Do you know of a reason that it is detected in 8.6 but not 8.5?

- Thank you

[Captain_Kirby]

Hi ecw,

I dont know exactly what the subVI is doing, so it might be worth diggin deeper into it to find out how it is producing its samples. It may have an elapsed time count before it gives a different sample. In this case, the timings may be a bit out of sync, or the elapsed time could be much greater then 10ms.

As far as the device detection in 8.5.1, ensure that the FPGA module is loading when you start LabVIEW 8.5.1, and also, ensure that the module was installed after the LabVIEW environment. There shouldnt be a reason you cant have the device detected in 8.5.1 and in 8.6 if installed correctly. You might also ensure the device is not running or in an error state when you try to detect it.