I think what you are asking is that you want to read one point from your instrument and plot it to a graph? If so, you will need an interface to your instrument, such as a GPIB or serial card, depending upon what tyep of instrument it is. Once you do that, you can use the driver software to interface LabVIEW with the instrument.
When you have that working, you will need to determine if their is a LabVIEW instrument driver for your instrument. If so, use that to communicate with the instrument and plot the data to a graph. If not, you will need to find which command strings the instrument accepts and send those using the hardware driver. Then you can read back the data and plot it to a graph.
J.R. Allen