Instrument Control (GPIB, Serial, VISA, IVI)
How to attach graph to Visa Read in labview for real time graph
You did not attach any program, just an image. That's not the same!
How does the string data in the read buffer look like? In order to chart it, you need to convert it to a numeric datatype.
You did not anwer how the received data looks like?
Also, how do you determine framing? Does the data contain a defined delimiter, for example?
Well, you seem to read a random number of bytes, whatever number of bytes happen to arrive at the port. Most valid measurements probably contain more than 1 character, so we need to know where one number ends and where the next number begins. Is there a special character separating values? Do you have documentation for the instrument sitting on the other end of the serial cable?
Since you say the hardware is in progress, you need to talk to whoever is developing it and agree on a format. With an ASCII format, I would recommend a comma or an End Of Line character to separate the data. If you are just getting a single channel's data, then I would highly recommend the End Of Line character. If you are getting multiple channels' data, then use a comma to separate the channels and send the End Of Line character after all of the channels' data is sent. Something like "1,2,3,4EOL" where EOL is the End Of Line character.
What this will allow you to do is use the termination character with you VISA Read. VISA Read will read the number of bytes you tell it or until the termination character is read, whichever comes first. So by using the termination character, you don't have to check the number of bytes at the port. You just set the number of bytes to read to something ridiculously high and let the termination character stop the read. You now have a nice frame with all of your data. If using multiple channels, use the Spreadsheet String To Array to convert to a numeric array.
