You sure can. There is a popular program to check on serial hardware, the loopback.vi. It sends out a signal and reads in a signal. You can modify the vi to send a signal to whatever you need to or receive a signal from whatever you want to. So if you just have an output signal to read in you can modify it to just read in that output signal into a graph or anything you'd like. So you could just get rid of "serial port write.vi" or that entire sequence if you wanted to. I hope that helps.
Another possible option is to use the Instrument I/O Assistant. It is an interactive tool that generates Instrument I/O and response parsing code for you. It is very helpful in establishing a connection and helping parse instrument response data. It is pretty high level and basic, so if you want to utilize any special serial VISA functionality it may not go as deep as you would like - but it can definitely help get you started.
