Ah, I see. You almost had it. The problem is that you are over-writing the entire text file in each iteration, so your text file only shows the most recent message.
To prevent over-write, you need to do two things (1) address the file by a Refnum (not a filename) and (2) set the file position to 'end' before writing. This will cause the new data to be appended to the end of the file.
To generate the Refnum, use the File Open Vi.
In this example, I'm using a random number generator to create the message and then writing it to the end of a file. In your program, you can just replace the random numer with your output message.
