Kasi - it appears that you are just writing your data to a comma-separated file and not an Excel file. Is this intentional? If the idea is to just write out a new row to your file every time that the user presses a button in your GUI, and so you don't want to overwrite the data that you had there already, then you should open your file for appending as
fid=fopen('in.csv','a+')
Declaring variables as global is unnecessary (unless you need to access this data elsewhere). When it comes to writing the data to file, just do
A=[b1,b2,b3,b4,b5,b6];
fprintf(fid,'%f\t',A(:,:));
fprintf(fid,'\n');
fclose(fid);
We use the \t to separate each column of data with a tab. Try the above and see if it does what you expect.
