Local History for InTouch
LGH files get their name from the *.lgh extension on the filename. The files are generated by the AVEVA InTouch HMI, also known as Wonderware InTouch in the market.
LGH files store local process history data records for tags/process values that have been configured for local logging. Prior to the existence of AVEVA Historian (also formerly Wonderware), LGH files were the only way InTouch stored data. They are still in use today as a means of having some local history available since historian applications are usually on other servers accessible over the network.
If you try to open an LGH file in Windows Notepad, you'll find that it is not human readable as you see here. InTouch comes with a utility called HistData that can access the files, but using it requires scripting and is limited to 2000 rows of data.
LGH File Inspector is a visual utility that can manage, query, and extract up to 1,024 tags and nearly 15 million values in a single query, and export that data to Excel, CSV, & FastLoad formats. Queries can be done on-demand, saved for re-use, and automated or scheduled for recurring usage.
