I am using Visa to control a serial device using rs232. After some bugs, we were finally able to talk to the instrument and get data back. I tried adding a control which did not work, so I went back to the oringial configuration. I can no longer communicate with the instrument. Everything is the same as it was when it was working. I was getting timeout errors at Visa Read, and now it looks like its timing out at the very beginning. We've cycled the instrument and closed and reopened the vi. I'm wondering if we need to flush buffer (using the vi), but I can't figure out how to get it to work. Any suggestions?