Plot data with date and time

I have an excel file which is created automatically and data is added every 10 minutes. I want to read and plot the days once a day, so I take the last 144 data points. When I plot x and y, the error message "Error using plot. Not enough input arguments."

I know that I have to convert my x vector, which contains the time data, somehow. I have looked at the forums and tried different approaches, but it has not worked so far.

x1=datenum(x,'HH:MM:SS'); 

This one didn't work especially since I don't know how to add the date next to the time.

so far i have only managed to extract the x and y values, which i need for now, from the excel file:

table=readtable('Datalogger.xlsx'); 
x=table.DatumUndUhrzeit;
x=x(end-144:end);
y=table.Temp_R_210__C;
y=y(end-144:end);

Answer 1

[KSSV]

thedates = datetime(datestr((x)));
y = str2double(y) ;
plot(thedates,y)