LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Read Historical Trend VIs do not return all of the data between start and stop.

My Main.vi manually writes data to Memory tags in DSC. If my Main is running, calls to Read Historical Trend.vi and Read Historical Trends.vi sometimes take a very long time (~60 seconds in some cases). In addition, most of the time the last data point from that time period is missing.

For example, I have a discrete tag that is False before the start time, and goes True and then False again before the stop time. I know that this happens because I can see it in the Tag Monitor. However, when I call Read Historical Trend.vi, only 2 data are returned: a 0 with a timestamp from before the start time, and a 1 with a timestamp just after the start time. There is no 0 with a timestamp befor
e the stop time, but there should be. If I wait for several and then try again, sometimes the data will be correct. But if I stop Main.vi and try again with the same exact timestamps, the data are returned immediately and nothing is missing.

I also occasionally get Error -1967390704 occurred at CIT_ReadStringTrace.vi. I'm not sure what causes that, because it doesn't happen every time.

I am using Labview 6.0.2, DSC 6.0.2 with the fixes, and the latest Logos (4.4).
0 Kudos
Message 1 of 3
(3,021 Views)
I have the same issue with LABVIEW 6.1, DSC 6.1 with Jan2003 fixes, and LOGOS 4.4.0.15. I've had a request into tech support for a few days. It sounds to me like some software revisions are going to be necessary. I have 4100 tags in the DSC engine with only 100 being logged.
0 Kudos
Message 2 of 3
(3,021 Views)

Jake,

We have identified the issue and developed a potential workaround. Please create an email (not discussion forum) request so we can contact you on this.

Regards,
Michael Shasteen
Applications Engineering
National Instruments
www.ni.com/ask
1-866-ASK-MY-NI

0 Kudos
Message 3 of 3
(3,021 Views)