Thanks again for severals answers to my previous question. My problem was that, when I was using the "Basic_Serial_Write_and_Read" VI to communicate with the ballbar (serial port), I was getting an error about accessing the port. Then, with the answers I got, I ensured that MAX and Hyperterminal were closed and tried again. And I'm back to my first error about timeout. In MAX, I'm able to read data from the ballbar. When I send *IDN?\n I receive A12345 (its name), when I send *S?\n I get the anticipated data from the ballbar. But, when I try to do exactly the same in Labview, I get timeout error (or access error if MAX isn't closed). So I'm still trying to figure out why I get this time error. I've checked all the properties (baud rate, bytes to read, ..) and even if I make the same procedure as in MAX, I get this error. I'm a bit confused about why there's a difference between MAX procedure and Labview, so if someone has an idea, I'd appreciate it a lot. Thanks again for helping me solving my problem.
