Thank you for the explanation of the timestamp format in the Blynk data and how to convert it into the Excel date value text. However, it’s better practice in Excel to use the internal timetime value rather than the converted text as in the example. So, I would use the formula
=(LEFT(UnixDateText,10)/60/60)/24+DATE(1970,1,1)+(GMT_Offset/24)
This converts the UnixDateText to the Excel datetime value (the floating number of days since 1/1/1900).
Then you can use a custom cell format like “YYYY-MM-DD HH:MM:SS” to display the number as a date/time value even though the date value is stored in the cell. This way, when you plot data in an x-y scatter chart as function of time, the axis will show the dates. If the time column is text, Excel will ignore it and plot the data as a simple line chart with the index value along the x-axis.