Yes indeed, that's exactly it.
I've got two blocks "SD utility delimited line" : the first one is mostly for constant texts (my column titles) and the second one contains data such as date, hour (ML15 & ML10) and process values.
I think you may be right on this one since when the key button is pressed, it writes titles on my CSV and then it writes values.
So that could certainly explain the value changement of MI900... thanks for your explanations. It's not so obvious when you begin.
That button is also used to start a process sequence. So it means I can find in my CSV the process beginning by looking for titles.
But from what I know, data is non-stop written. I don't necessarily need to press the key to start recording data. When I extract data and then delete my file on SD card, if I look a few minutes after, I will have values on it. Basically, pressing the key button is only used to write titles in this code.
I tried accessing the SD card (using unitronics SD card suite) for a while and then looked at the file but there wasn't any time gap so I'm not sure there's a conflict.
Also, I can't really explain why SB41 is used to reset MB252 because, to me, MB252 is always set. If it wasn't, it couldn't be possible to write data continuously. I guess there's a better way of coding it but changing everything could be risky.
Again, thanks for your support. At least, I'm learning and understanding better thanks to you.
Take care.