changing day start

[bellmike]

was wondering if anyone has changed the setting from 12.00am to 9am and back again and if this is possible. and how does it affect files
my station is a vp2 and wll
cheers Mike

[sfws]

how does it affect files

All files except alltime.ini are affected in some way. Much of the Cumulus design is based on daily extremes, those are highly dependent upon what hours are included in each day.

My advice would be, if you do change rollover time, archive the old files in data folder, and let the software create a new set of files.

anyone has changed the setting from 12.00am to 9am and back again

Do you really mean "and", or did you mean to type "or" there?
Cannot believe anyone would want to change the rollover time twice.

Certainly, a number of people have changed rollover settings once, presumably after giving the matter more thought than when they first started using the software. A forum search might produce more details, but guesswork suggests alignment with some other reporting stations might be main reason. Possibly, some changes in Cumulus that provide some "since midnight" values might now favour choice of 9am rollover?

A more popular change is to use a computer that does not ever have daylight saving time, thus avoiding the issues on days when clock change; that does not requiring archiving of old files, as only two days per year are affected.

[bellmike]

Thanks for your reply I was having some problems and wanted to compare some data to my wll I have only been using cumulusmx for a short while and just getting used to things. I appreciate your advice and think I will not change it just for the sake of it . Especially when my understanding of these things are limited
cheers Mike

[sfws]

I was having some problems and wanted to compare some data to my wll

If I understand your posts in other topics correctly, the actual issue is that you have 9am rollover in MX, but want to compare to calendar day based WLL data, and all you want to compare is data for just part of last month (August) and for so far in this month (September).
This is not what your initial post in this topic asked (there you wanted to change a midnight rollover to a 9am rollover and then go back to midnight rollover, to do that is far more complicated). If my revised view of what you actually want to do is now correct, there is not a lot of work needed to just compare that short period.

You would create a copy, of all files in your whole MX installation, in another location/directory (therefore keeping MX running as now, and ensuring none of your existing data files are affected). If your copy installation does not already have "CreateMissing.exe" and "CreateMissing.exe.config", add these to this new location (download link found at https://cumuluswiki.org/a/Software#Create_Missing).

In the copy installation:
Choose an editing program that is designed for programmers, coding editors like Geany, Notepad++, NoteTab, and many others are okay. The Microsoft Notepad that comes with your Windows 11 could be used if you can't use a better editor, but you need to use its Save as option and select the saving mode as UTF-8 without BOM (byte order mark) as by default Microsoft (and Google) normal save operations may add two unwanted BOM characters to start of file (preventing Cumulus from understanding the file).
First, edit "Cumulus.ini" at the new location; navigate to section headed [Station] and find parameter that currently reads RolloverHour=9, change that nine into a zero, which is how it would be for midnight rollover.
Second, edit your data\Aug22log.txt and data\Sep22log.txt files in the new location. Move the lines at end of the August file that have dates relating to 1 September (the times at start of these lines will be midnight to just before 9am) out of that August file and into the start of the September file. This will effectively convert those 2 files to how they would be for midnight rollover.
Third, delete the copy of "data\dayfile.txt" in the new location, that eliminates all existing daily summary entries based on 9am rollover.
Finally, run the "CreateMissing.exe" file found at the new location, it will read your RolloverHour=0 in Cumulus.ini , read your edited August and September files, and finally it will create a new version of "dayfile.txt", with contents as they would be for midnight rollover.

I don't know if those 3 converted files are enough for your comparison? If so, job done.

If you do really need more, then you could stop your normal MX, then run the version of MX in the new location for a short time.
In interface of MX in new location, go to Edit menu, then work through all the extreme record editors. In each, use the "Copy xxx" options (highlight figures and times in "dayfile.txt" column) to replace every existing extreme record with a new extreme record value/time based on data in the new "dayfile.txt". You could take screen shots of every edited editor page if you need that visual presentation.
Next, stop this copy based MX, and restart your normal MX using the unchanged files, it will carry on from when it was stopped. You may have a gap in your data, but hopefully it will be a short one.
You will meanwhile have in the copy location the full set of extreme record files to use for the comparison, but the comparison may have to be done in the unfriendly way of reading files, if you did not take screen shots.

[bellmike]

my apologies for the late response I appreciate the help you have given me I don't understand half of it but I can do some things if I read it 10 times and do it step by step my biggest problem is I am just starting out and I don't understand a lot of the language been used so if I do want to try what you have suggested I now have this as a reference to come back to
I have moved on to trying to set up my website now and where I though cumulus was not reporting properly has been sorted out by me learning on the way. I have had some great help from people on this forum and i appreciate it
cheers Mike