OpenHistorian Export Data with Different Frame rates

Hi everyone,
i am using OpenHistorian to gather data from a PMU for quite some time now. We had been using this data in case of frenquency flactuations but a need has risen for data to be exported on a monthly basis from the said PMU.
On the OpenHistorian web manager > Trend/Export Measurements> Export Data i’ve been trying to lower the file size of the exported CSV by changing the Frame Rate.
Even by switching it to 1 frame per hour, the timestamps on the exported CSV are displayed on a second by second analysis, resulting into massive csv files.

Am i missing something that i need to configure regarding the frame rate? For example, if i want to extract data every 15minutes for an entire month what are the settings i need to modify to get that result?

Hi Renos,

FYI, your first issue is that the frames per minute and frames per hour options straight up don’t work due to a type-mismatch bug. We’ve fixed that just now.

However, my testing suggests there are some deeper mathematical issues with the minutely and hourly exports that makes the whole thing a bit hit-or-miss. We’re still working through that issue as well.


Hi Stephen and thanks for the quick reply.
I understand exporting data on different analysis settings can be a bit tricky since some values that might be considered important could be lost ( ie. underfrequency events) making the whole thing quite complex.
I am a bit of a novice so forgive for the next question, when the problem has been solved is there anything i should do on the openHistorian software? ie update or replace a certain file?

For the change we just made, you’ll need to update the TrendMeasurements.cshtml file in the wwwroot subfolder. As for the math issues, I expect those will need to be fixed in ExportDataHandler.ashx.cs which gets compiled into openHistorian.exe, potentially with a few more edits to the aforementioned cshtml file as well. Honestly, I would recommend just downloading and installing the latest nightly build version once all the fixes are applied.