Actually, if you're using the 34401 to measure voltage then LabVIEW
already comes with the instrument driver for that model. It's in the
Instrument I/O -> Instrument Drivers palette. The examples are not in the palette, but they are on disk in the <labview>\instr.lib\Agilent 34401 directory.
You first
need to make sure you can talk to it. Are you using GPIB or serial? You
also need to make sure the instrument is configured to use the same.
This is done using the instrument's front panel - check the instrument's manual on how to do this. If you don't have the manual, you can download it from Agilent's web site.
Start with something simple. Open the "Read Single Measurement" example. Select the correct VISA resource name: if you're using GPIB select the instrument based on its address; if you're using a serial connection, select your COM port and configure the baud rate, etc. - unless someone has changed the instrument's configuration, the defaults should work. Run it. Do you get a reading? If so, half your battle is done.
If you can get a reading using the example then you can loop it by placing a loop around the "Read Single Point" VI in the example VI. Connect a Stop button to the loop's condition terminal and place a timer in the loop so it takes a reading at (approximately) your desired rate. You can add a waveform chart to the front panel and connect it to the same point as the "Measurement" indicator on the example.
Post back when you've gotten this far.
P.S. If you haven't already done so, you should go through the tutorial(s) and look over the material in the NI Developer Zone's Learning Center which provides links to other materials and other tutorials. You can also take the online courses for free.
