How to log(append) the data to excel sheet continously when using 'while' loop?

Hello! I am using MATLAB to read a real-time serial data. I am using a 'while' loop to iterate the loop continuously. Within the while loop I have a resultant matrix which stores the variables i require. Then I use 'xlswrite' command to store these values. But the problem is, for every iteration this file 'sampletest.xlsx' gets rewritten. I want the new values of every iteration to be stored in the same file i.e. they have to get appended below the previous set of values. How can I achieve this? Hoping to find some help.

while <condition> 
. 
.
.
filename = 'sampletest.xlsx'; 
D = [(vfl) (vfr) (vrl) (vrr) (temp) (tps) (delta) (time) (vv) (Ax) (s_rr) (s_rl)] %concatenated matrix 
sheet = 1;
log_data = xlswrite(filename,D,sheet);
.
. 
end

Answer 1

[Walter Roberson]

See https://www.mathworks.com/matlabcentral/answers/392014-how-to-save-for-loop-data-to-same-excel-file-of-variable#answer_313004