OpenHistorian and Grafana 9.x - no_data return when time range < 24 sec

Since the upgrade of my openHistorian version to 2.8.249, embedding 9.1.5 version of Grafana (which is great because in addition to the new Grafana functionalities introduced compared to the previous version 7.x, the OpenHistorianAlarmPanel and GPAPhasorMap plugins work now!), I encounters the following problem: when I try to display a TimeSeries type graph of the frequency of a PMU, if the requested time range is < 24 seconds then I have the No_Data message displayed and Grafana returns ‘Query error: 500 internal server error’.
If I set a time interval of 24 seconds on the same graph; then it works. On an earlier version of OpenHistorian (thus implying a version of Grafana < 9); the graph is displayed without problems; even for a period of 1 second. My datarate is 50 fps. PDC data source for those two openHistorian servers is the same.

Maybe an issue caused by the ‘new’ version of the OHData Source that as been adapted to work with the new version of Grafana ? Or maybe a new config parameter ?

Could you please confirm that you can reproduce the issue ?

Thank you very much,



Hi Stephane, we will verify this.

Thank you,
In addition to help investigate : the following error is shown in the OH Console when the no_data error appears :

Note that the 24 seconds mentioned in my previous message is not a fixed value :
It can vary according to a criterion that I do not know.

I’ve found a reference to this ‘tolerance’ and ‘subinterval’ mentions in the openHistorian/TimestampSeekFilter.cs code.

Found and corrected this issue, thank you for reporting. Also, Grafana 9.5.1 is now in nighty build, if you would like to test:

Please let me know if you find any other issues with this version of Grafana,


Hello Ritchie,
Thank you very much for the quick fix you provide.
I confirm that now everything works fine ! :+1:

Many thanks !