read historical trend is hanging up after 100-250 consecutive reads

[unclebump]

I have a state machine setup to read historical data for a selected array of tags. I have several different sets of tags that I want to read. The state machine will read data and display a trend for each of the eights tags in the array. The vi works fine on another computer. I have moved to another computer and the read historical trend vi hangs after anywhere from 100-250 total executions of the 'read historical trend vi' that comes with labview. open the file 'my 90hd all stations at once StateMachine.vi' and look at state 3 in the case structure. Inside the file 'read hist data and turn into cluster.vi' is where the program is hanging up at the read historical trend vi. Since the read histori
cal trend vi is password protected, I can't get inside it to see what is happening. I am running logos 4.4.0.17 and the dsc6.1 updates from feb26 2003. this is on a win 2000 machine. I have also deleted the entire CITADEL database and created a new set of data. This same style of vi exectues on another computer without hanging while reading historical data. I have the state machine setup to auto update the data every 900 seconds and it will hang eventually after so many updates. Any thoughts on fixing would be appreciated.

[Roli]

I did not run your example/db. If you say that it happens on one PC but not on another, I guess it depends on a Windows 2000 OS setting.

You sould make sure Start >> Settings >> Control Panel >> System >> Advanced >> Performance Options >> Optimize performance for: is set to Applications.

I've seen this before and NI R&D told me that this is maybe an issue in the Citadel 4 interface. However, with the new LabVIEW DSC 7 and the new Citadel 5 this issue seems to be resolved and you should be able to develop a multithreaded application in LabVIEW DSC even with the setting to be in Background.

Please let us know if the workaround fixes the problem for the Read Historical Trend.vi hang and check out the cool new features in i.com/labview/launchpad.htm>LabVIEW 7, LabVIEW 7 DSC Module.
LabVIEW Datalogging and Supervisory Control Module Release Notes

Hope this helps
Roland

[unclebump]

It was set to background. I even have the app note saved in my files that tells me to set it for applications. Is there anyway to check this setting inside a vi?? I have been waiting to convert to labview7 till we see if there are any software issues. I have been working on this application for quite some time and did not want to introduce any unknown issues. I like the child panel feature to simplify viewing sub-vi data. I would love to see a way to have a tag associated with multiple groups in the tag engine. Then you could retrieve data in different ways by reading all of the tags in a group, rather than specifying each tagname in an array control

[unclebump]

I converted to LABVIEW 7 and CITADEL 5. The response time of reading historical data seems to have improved significantly. No issues with the conversion, but I did have to manually switch from the legacy historical vi's to the new versions. I really like the new timestamp data format.