CLAD Homework 6 Solutions
1. D
In NI LabVIEW software, the order of execution is controlled by the flow of
data (data flow) though wires rather than the sequential order of commands.
This allows you to create a block diagram with simultaneous (parallel)
operations. When you have parallel loop structures, you cannot use wires to
communicate data between the two loops because data flow prevents parallel
operation. To overcome this, you must use variables. With variables, you can
circumvent normal data flow by passing data from one place to another
without connecting the two places with a wire.
2. C
The only answer option that can be passed from calling VI to subVI is the
control reference. The reference can then be used with Property Nodes and
Invoke Nodes to call properties and methods, respectively. The data type is a
property of the control
3. A
Strip charts start plotting from left to right and continue to scroll while plotting.
Scope charts start plotting from left to right and continue until the chart is full.
Then the chart is cleared, and plotting resumes at the left. Sweep charts
behave similarly to scope charts, except that once the chart is full, sweep
charts start plotting at the left and progressively overwrite previously plotted
data. There is no such thing as a Step chart in LabVIEW.
4. D
You must either look at an output error cluster or an error dialog to find the
error code.
5. D
The Merge Errors function does not display any dialog. The One and Two
Button Dialog functions are for general purpose and are not the best for error
handling applications. There is no error input on these functions. There is no
VI with the name Generate Front Panel Activity. The Simple Error Handler is
the best choice because it accepts an error cluster as an input and displays a
dialog to the user in the event of an error.
6. A
You can place critical data or sections of code in functional global variables.
Since functional global variables are non-reentrant VIs, the possibility of race
conditions is eliminated.
7. D
Waveform Graphs either accept 2D arrays or a 1D array of clusters
containing waveform data. Waveform Graphs do not accept X and Y data
interleaved in a 1D array as answer A suggests.
8. B
The Probe tool allows the developer to see data in a wire during execution,
but it does not slow down execution at all. Highlight Execution slows down
execution and displays the flow of data, and the Single Stepping tools allow
the developer to look into subVIs.
9. B
Breakpoints cause the VI to pause execution and wait for the developer to
decide to start single-stepping or to unpause the execution.
10. A
Property Nodes are designed for modifying front panel objects
programmatically. Answers C and D do not make sense because modifying
front panel objects is not what variables do. Because we are not using
subVIs, answer A is a better choice than answer B because an implicit
Property Node will work and does not require the extra inputs that the explicit
Property Node requires.