how to use the internal clock w/ crank angle degree (CAD) recording in labview 5

[bobbylee]

I have LabView 5 on a win98 w/ AT-MIO-16E-2 & PC-TIO-10 for engine controlling.  I am not sure if I could use my pc's internal clock to record my CAD data (400 signals / revolution) that I could get CAD vs real time data.

Thanks.

[Courtney_L]

Hey bobbylee,

In LabVIEW 8.6 there is a "Get Date/Time in Seconds" VI that will get the current time based on your system clock. Is a similar VI available in your palette in LabVIEW 5? Once this is obtained, you can format this into more usable info with the "Get Date/Time String" VI.

Here is a screenshot of the Get Date/Time in Seconds VI in 8.6:

Let me know if you have access to something similar!

Regards,

[bobbylee]

Hi Courtney,

Yes, I have found the icon, but I am not sure how to hook this one to get what I want.  Thank you.

Bobby

[Courtney_L]

Hi bobbylee,

What rate are you acquiring samples at? For a reasonably low sample rate, you could just put this VI in the loop where you're performing your reads and then append the data point with the corresponding time stamp in an array. That way, every time you take a sample you also take a measure of the current time as shown by your PC's sytem clock. Here is a screenshot of the two different output types:

That being said, if you're acquiring at a very fast rate this may not be a sufficient solution. Let me know what you think!

Regards,

[bobbylee]

Courtney,

Thank you for the screenshot.  I am taking the data from a crank angle degree (CAD) sensor.  It has 400 signals per revolution and I am running at 600 rpm, so it is equivalent to 4000 signals / second.  Will the vi you provided be sufficient?  I see the current time show 5:31:17.072, but the time string only shows 5:31.  Is it possible to record the former?

Bobby

[Courtney_L]

Hey bobbylee,

To get the current time, just use the first VI (you can see in the block diagram where I have wired the current time indicator), so you can ignore the other VI if this is the type of output that you're looking for. I think 4000 signals/sec could be pushing it (it's been awhile since I've used LabVIEW 5.0!). I would try it out and see if you are missing any data points. If the points are missing then you'll need to take another approach. 

Best,

[bobbylee]

Hi Courtney,

I tried a simple array to see if the time recording could be fast enough.  Unfortunately, I do not think my desired scale (~0.00025 s) is achieveable by the method above, which works perfectly for low frequency.  Is there any other way that I could record both current time and my data?  Thank you very much.

[Courtney_L]

Hey bobbylee,

What file output VIs do you have available in your function palette - I believe TDMS is newer than LabVIEW 5.0, but what VIs do you have in your File I/O palette? I've pasted what I see in the newer versions of LabVIEW below:

Let me know if any of these look familiar! If you have TDMS, it's a very fast way of acquiring data with an initial time stamp and all of the delta t's for each value read.

Best,

[bobbylee]

I can only write my data to a txt file like a matrix, and then I use Excel to open it.

[Courtney_L]

Hi bobbylee,

Do you have access to any machines with a more recent version of LabVIEW installed for testing purposes? In the mean time I will try to get access to a machine with LabVIEW 5.0.

Best,