Right now, if it outputs more than 100 bytes, you've limited yourself to reading 100. Then you proceed to close and reopen the port which means you are losing data after that.
Right now you don't have a LabVIEW programming problem. The problem is reading the device's manual and learning more about its communication scheme. Once you have those details, then it is possible to figure out how to make LabVIEW work with it accurately and efficiently (unless there communication protocol is a real mess!)
