Open/close file in while loop

Question

VI reads 3 temperature sensors connected to RS232 port ( external rs232/RS485 converter , sensors have different addresses). When VI starts , user is asked to chose location and filename of data log file for each sensor ( write to the same file or to new file).
3 START/STOP buttons controls data logging from sensors. Right now it just starts or stops data reading from sensor and writing to file. What I would like to have is that user is asked to enter file name and location not when wole VI starts, but when he START/STOP button is pressed. ( When user press button 1, he is asked to enter file name and location. When data logging from that sensor is stopped, file is closed. When data logging is started again, user again must select data log file). The same for START/STOP buttons 2 and 3.
Attachments:
GIA10N_example.vi ‏116 KB

Answer 1

Hello.
The short answer is that you have to put the "Open/Create/Replace File.vi" inside the case stucture, so that that executes each time a button is pressed. You should also be closing the files after you write to them, which I did not see you doing in your VI.
I am attaching a modified version of your VI which should perform what I understand you want. I am using the "Write Characters To File.vi" which is an easy top level VI for writing data to files, which opens, writes and closes the file each time it is executed.
I also removed the local variables and used the boolean buttons directly inside the sequence structure. In general, you should avoid the use of local variables unless it is absolutely necessary.
Hope this helps.
Alejandro
Attachments:
GIA10N_exampleModified.vi ‏82 KB