I. Objective:

To give the student experience in handling GBIP interfacing and to show the student how computers and other pieces of equipment communicate with each other. Experience in these fields will aid in the transition between using LabVIEW as a virtual instrument and using LabVIEW as an actual aid in research and data acquisition.

II. Procedure:

1. During the Initialization procedures, read the current SR510's front panel values of the sensitivity and pre-time constant and display them on your VI front panel. If sensitivity or pre-time constant values change using the controls for (b) and (c) below, then the displays should change as well.
2. Controls the Sensitivity of the Lock-in. Make sure to update your sensitivity display.
3. Controls the Pre-time Constant. Make sure to update your sensitivity display.Features (b) and (c) might be most effectively implement using a "change settings" switch on the front panel which then pops up a sub-VI.
4. In addition to the controls discussed above, put a Boolean switch on the front panel. When the switch is pressed, read the measured voltage from the Lock-In (Q command) a total of 10 times. The user should be able to vary the delay between the reading of data points from 1 to 10 seconds. Display a numeric indicator of the current data point and display the data as it is being generated using a chart recorder.

III. Discussion:

1. A VI front panel item can only be an indicator OR a control. How did you handle the problem of setting the sensitivity and time constants to their current values during initialization, but allow them to change during the running of the VI?
2. Should the user be allowed to change the sensitivity or time constant DURING the acquisition of data from an experiment? Why or Why not?

Please email your discussion questions responses and the VI (and all required SubVIs) to gnita@njit.edu