CLAD Exam

why use state programming?

-can change the order of a sequence -can repeat an item in a sequence more often than others -states execute only if certain conditions are met -can stop the program immediately

what is the VI server used for?

-programmatically control front panel objects and VIs -dynamically load and call VIs -run VIs on a computer or remotely across a network -programmatically access the labview environment and editor (scripting)

what are property nodes used for?

-read and write the properties of an object -make modifications programmatically to the appearance of the front panel in response to certain inputs

Which file format(s) is best for sharing data? ASCII, TDMS, or Direct Binary?

ASCII (next best is TDMS)

Which mechanical action cases a Boolean control in the FALSE state to change to TRUE when you click it and stay TRUE until LabVIEW has read the value?

Latch when pressed

square route of a negative number will result in

NaN

which file formats allow for high-speed streaming?

TDMS (NOT binary, ASCII, LVM)

If an input to a function is marked with a red dot (known as a coercion dot), what does this dot indicate?

The value passed into a node was converted to a different representation.

what causes events?

actions that the user performs (ex. mouse click, keyboard, etc). similar idea to pushbutton interrupt

error handling

anticipation, detection, and resolution of warnings and errors

which file formats have inherent attributes?

binary and tdms (NOT ASCII, LVM)

which file formats allow random read/write access?

binary, TDMS, LVM (NOT ASCII)

what do invoke nodes do?

call methods or actions on objects (referenced items).

type definition

can have a different name, description, default value, size, color, style of control as long as the data type matches the master copy of the control

strict type definition

everything about the control must be identical across all instances (excluding name, description, default value)

what happens when errors are handled using error clusters

execution continues, but the node with the error is skipped. errors are propagated and passed to successive nodes

what type of property node can you use to update a property from inside a subVI?

explicit property node

which mechanical action (switch or latch) is guaranteed to be read at least once by labview?

latch

why would you use a notifier over a queue to pass data between parallel loops?

notifiers can broadcast a notification to multiple loops (with queues, elements can be dequeued only by one loop)

how many event structures should you place in a loop?

one

latch until released

value of button will change when button is pressed, then change back once the button is released and labview has the value. it will stay pressed until the button is released and labview has read the value.

wait (ms) - what does it do?

wait until input ms amount

Initialize Array inputs (1d and 2d)

1d: element (what you initialize it to), dimension size (how many elements there are) 2d: element (what you initalize it to), num rows, num cols)

delete from array (1d and 2d)

1d: original array, length, index. deletion begins at the index (i.e. ele at index is deleted) 2d: original array, length, index (row), index (col). same as above

insert into array (1d and 2d)

1d: the original array, the start index, the new subarray to be inserted. the new sub array is inserted such that the first element of the sub array becomes the element at the start index. 2d: the original array, the start index (row), the start index (col), the new sub array. new array is inserted such that first element becomes element at the start index.

which file formats are easily exchangeable?

ASCII, TDMS, LVM (NOT binary -- i guess bc binary just looks like a bunch of symbols)

what are common log file formats?

ASCII/LVM, binary, TDMS

Divide by zero will result in

Inf

Which file format(s) is best for efficiency? ASCII, TDMS, or Direct Binary?

TDMS, Direct Binary

Which file format(s) is best for numeric precision? ASCII, TDMS, or Direct Binary?

TDMS, Direct Binary

does Show Tool Bar operate on a VI or Control class?

VI

error handler

a vi or code that changes normal flow of program execution when an error occurs

execution timing

allows the processor time to complete other tasks

automatic error handline

at run time, labview suspends execution, highlights node, and displays error dialog box

which would NOT result in a broken run arrow? a. a subVI is broken b. the diagram includes a divide by zero c. a required subVI input is unqired d. a boolean terminal is wired to a numeric indicator

b (would result in an output of infinity, but the code would still run)

which file formats have a small disk footprint?

binary, tdms (NOT ASCII, LVM) -- probably bc more compact

Integer color

blue

1-d array data line type

bold straight

error codes can be zero/nonzero/both? what is the status if an error has occurred?

both; true

waveform data type

carries the data, start time, and dt of a waveform

does Format and Precision operate on a VI or Control class?

control

does Reinitialize to Default Value operate on a VI or Control class?

control

does Visible operate on a VI or Control class?

control

2-d array data line type

double straight

Boolean color

green

software control timing

times a real-world operation to perform within a set time period. controls the frequency at which a loop executes

implicitly vs explicitly linked property nodes:

implicitly linked: right clock control and select what object to link the node to explicitly linked: node has a reference input, which determines which object the node will operate on

why would you use event structures over polling?

minimizes CPU usage. With polling, you must continually poll the front panel for changes. Also, event structure does not lose user events, because it uses an event queue to store and handle events in the order in which they occur. Polling runs the risk of missing the occurrence of an event while another one is being handled. also, events execute on demand

can you have an array of arrays?

no

if you change the characteristics of a type definition control, will it change all instances of the type def?

no

warning codes can be zero/nonzero/both? what is the status if a warning has occurred?

nonzero; false

why would you use a queue over a notifier to pass data between parallel loops

notifiers don't buffer data, so receiving loops only receive the latest notification

notify events vs filter events

notify events: when a user action has occurred, complete a task filter events: when a user action has occurred, evaluate if the task is safe to complete (ex. is the word doc that's about to be closed saved?), and if it isn't, don't do it

if the input label of a sub VI is dimmed in the context help window, this terminal is:

optional

Floating point color

orange

String color

pink

waveform graph

plots all points at once

sweep chart

plots left to right. a moving vertical line marks the beginning of new data and moves across the display from left to right as it adds new data. lets you compare old vs new data. kinda like those radar graphs in submarines (idea-wise)

strip chart

plots left to right. keeps plotting continuous new data, like a paper tape strip chart recorder (e.g. lie detector graphs)

scope chart

plots left to right. when it reaches the right border, it erases the plot and begins plotting again from the left border.

waveform chart

plots points as they come in. Scope, sweep, strip.

use queues or local variables to transfer data between parallel loops?

queues

draw backs of using variables?

race conditions may occur (situations where the timing of events or scheduling of tasks may unintentionally affect outputs or values). for ex: two different computations running in parallel, their results passed to the same local variable. we don't know what value the local variable will hold.

if the input label of a sub VI is plain in the context help window, this terminal is:

recommended

after opening a file, what output does the open/create/replace file i/o function return?

refnum out (different from file path)

functional global variable

removes possibility of a race condition

if the input label of a sub VI is bolded in the context help window, this terminal is:

required

in what order are properties executed in a property node?

top down

in relation to state transition diagrams, what is a state and what is a transition?

state: part of a program that satisfies a condition, performs an action, or waits for an event transition: condition, action, or event that causes the program to move to the next state

error cluster elements

status (true if error occurred); code (32-bit signed int); source (string)

dynamic data type

stores the info generated or acquired by an express vi

path data type

stores the location of a file or directory

what is a sequence structure?

structure with frames, where each frame executes in order

what are notifier functions?

suspend the execution of a block diagram until it receives data from another section of the block diagram or from another VI running in the same application instance

which mechanical action for a windows dialog?

switch until released

polymorphism

the ability of VIs and functions to automatically adapt to accept input data of different data types; arithmetic functions

modularity

the degree to which a program is composed of discrete modules such that a change to one module has minimal impact on other modules

switch when pressed

the value of the button will be true when the button is pressed. It will stay pressed until you press it again

latch when released

the value of the button will change when the button is released. when the value is read by labview, it will change to the default state. it will stay pressed until labview reads the value of the control. then it will return to its default state

scalar data line type

thin straight

latch when pressed

value of button will change when button is pressed. when value is read by labview, it will change to the default state. it will stay pressed until labview reads the value of the control. then it will return to its default state

switch when released

value of he button will change when you release after pressing it. it will stay pressed until you press it again

switch until released

value of the button will change when the button is pressed, then when it is released it will change back. it will stay pressed until you release it

elapsed time express VI - what does it do?

wait until input seconds (not ms) amount

wait until next ms multiple - what does it do?

waits until next multiple of input ms amount

weakly vs strictly typed control references

weak: more flexibility with the kind of data they accept strict: accept only control refs of exactly the same data type

which structure must run at least one time? for loop/while loop/both

while loop

how to avoid race conditions from variables

write to variable from one source, read from it from any number of places. try to use wires over variables most of the time.

if you change the characteristics of an enumerated type, will it change all instances of the enum?

yes

why might you want to avoid using a sequence structure?

you can't stop the execution in the middle of a sequence. the order of the sequence is set, and can't be changed (for this reason, state machines would be preferable)

manual error handling

you control when dialog boxes appear, propagate errors with error clusters, terminate error chain with simple error handler VI

why might you want to use a sequence structure?

you don't have to wire the errors to specify a sequence