Do you still have a question about this? There are a few things that you can do to try to find where the error is coming from.
1. Use highlighted execution. If one of the VIs in your code is erroring out, then you should be able to see it. To use this feature, go to the block diagram, and click on the light bulb near the upper left hand corner of the window. Then run your VI by either pressing "CTRL-R" or clicking on the run button. When you're done with highlighted execution, disable it by clicking on the light bulb again.
2. Use Error Handling. Currently, you are using a sequence structure to control how you go from one step to the next, and you have no error data being passed from one step to another. Typically this is bad. Sequence structures have their place in LabVIEW, however if all you are doing is trying to ensure that one thing or another happens before something else, all you need to do is use the error lines - that is, connect the "Error Out" Terminal from one VI to the "Error In" terminal of another VI. This has at least three benefits.
1. You don't need the sequency structure any more (at least in this basic case).
2. Your code is optimized. Typically subVIs are developed so that if an error has occurred previously, the subVI will execute much simpler code.
3. You can find the source of errors much more easily.
3. Use instrument drivers or use VISA (at least in the beginning). With the instrument driver supplied, at least al the basic functionality that you might need, including resetting the device, should be included. Use the instrument drivers to do this.
Finally, have you looked into taking a LabVIEW basics or a LabVIEW instrument control class? You might consider it if you've never worked with LabVIEW before.
