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2020-09-28T20:51:05Z

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{{LabVIEW Palette Object Information|palette=Functions Palette/Programming/Comparison{{!}}Comparison palette|type=vi|icon=Comparison Palette - Ex Inst Comparison.png}}

The '''Comparison''' Express VI compares input items you specify to determine whether values are equal, greater than, less than, and so on.
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== Usage ==
=== Dialog Box Options ===
{| class="wikitable"
! Parameter
! Description
|-
! Items to Compare
| Contains the following options:
*'''Data points'''—Compares the data points of the signals in '''Operand 1''' to the data points of the signals in '''Operand 2''', the value you specify in '''Value''', or the '''Constant Value to Compare Against''' input.
*'''Timestamps'''—Compares the initial time stamps (t0) of the signals in '''Operand 1''' to the initial time stamps (t0) of the signals in '''Operand 2''', the value you specify in '''Value''', or the '''Constant Value to Compare Against''' input.
*'''Time between points'''—Compares the time between points (dt) of the signals in '''Operand 1''' to the time between points (dt) of the signals in '''Operand 2''', the value you specify in '''Value''', or the '''Constant Value to Compare Against''' input.
*'''Number of data points'''—Compares the number of data points of the signals in '''Operand 1''' to the number of data points of the signals in '''Operand 2''', the value you specify in '''Value''', or the '''Constant Value to Compare Against''' input.
*'''Signal name'''—Compares the signal names of the signals in '''Operand 1''' to the signal names of the signals in '''Operand 2''', the value you specify in '''Value''', or the C'''onstant Value to Compare Against''' input. When comparing signal names, you can use wildcards to match strings. You can use the question mark character (?) to match any single character. You can use the asterisk character (*) to match any sequence of zero or more characters.

If you select '''Signal name''', the '''Comparison Condition''' section is disabled and set to = '''Equal'''.
|-
! Compare Condition
| Contains the following options:
* '''= Equal'''—Determines if two inputs are equal. Because all comparison operations are floating-point operations, consider using '''Equal within tolerance''' for equality comparisons.
* '''<> Not equal'''—Determines if two inputs are unequal.
* '''> Greater'''—Determines if the first input is greater than the second input.
* '''>= Greater or equal'''—Determines if the first input is greater than or equal to the second input.
* '''< Less'''—Determines if the first input is less than the second input.
* '''<= Less than or equal'''—Determines if the first input is less than or equal to the second input.
* '''Equal within tolerance'''—Determines if the inputs are equal within the tolerance you specify in '''Tolerance'''.
** '''Tolerance'''—Specifies the level of tolerance to use when determining if an input is '''Equal within tolerance'''. The default is 0.01.
* '''In range'''—Determines if an input falls in the range '''Minimum''' and '''Maximum''' specify.
* '''Out of range'''—Determines if an input falls out of the range '''Minimum''' and '''Maximum''' specify.
* '''Minimum'''—Specifies the minimum value of the '''In range''' and '''Out of range''' comparisons. The Express VI includes '''Minimum''' in the range. The default is 0.
* '''Maximum'''—Specifies the maximum value of the '''In range''' and '''Out of range''' comparisons. The Express VI includes '''Maximum''' in the range. The default is 1.
|-
! Comparison Inputs
| Contains the following options:
* '''Second signal input'''—Compares the '''Operand 1''' input of the Express VI to a second signal input as opposed to a value you specify in '''Value''' or the '''Constant Value to Compare Against''' input. Select this option to include the '''Operand 2''' input on the Express VI. If '''Operand 1''' and '''Operand 2''' are the same size, each item in '''Operand 1''' is compared to the corresponding item in '''Operand 2'''. If '''Operand 1''' and '''Operand 2''' are of different sizes, all the items in '''Operand 1''' are compared to the first item in '''Operand 2'''.
* '''Value'''—Compares the '''Operand 1''' input to a constant value you specify. The default is 0. If you wire the '''Constant Value to Compare Against''' input, the VI uses the value that this input specifies instead.
** '''Point value'''—Specifies the constant value with which to compare the '''Operand 1''' input. The default is 0.
** '''Timestamp value'''—Specifies the timestamp to apply to the signal. This option is available only if you place a checkmark in the '''Timestamp''' checkbox.
** '''Delta time value'''—Specifies the constant value with which to compare the '''Operand 1''' input. The default is 0.
** '''Number of points value'''—Specifies the number of points to compare. The default is 0.
** '''Signal name value'''—Specifies the name of the signal.
|-
! Result
| Contains the following options:
* '''One result per data point'''—Returns one result per data point. This option is available only when you select '''Data points''' from the '''Items to Compare''' pull-down menu.
* '''One result per channel'''—Returns one result per channel. When you select '''Data points''' from the '''Items to Compare''' pull-down menu, '''One result per channel''' returns 1 only if all data points in the channel pass the specified comparison. If any point fails, it returns 0.
* '''One result for all channels'''—Returns one result for all the channels. When you select '''Data points''' from the '''Items to Compare''' pull-down menu, '''One result for all channels''' returns 1 only if all data points in the channels pass the specified comparison. If any point fails, it returns 0.
* '''Invert result'''—Inverts the outputs.
|-
! Result Name
| Contains the following option:
* '''Change Express VI name to name of function'''—Changes the name of the Express VI on the block diagram to the name of the function you select in the '''Comparison Condition''' section of the configuration dialog box.
|-
! Input Signal
| Displays the input signal. If you wire data to the Express VI and run it, '''Input Signal''' displays real data. If you close and reopen the Express VI, '''Input Signal''' displays sample data until you run the Express VI again.
|-
! Result Preview
| Displays a preview of the measurement. The '''Result Preview''' plot indicates the value of the selected measurement with a dotted line. If you wire data to the Express VI and run the VI, '''Result Preview''' displays real data. If you close and reopen the Express VI, '''Result Preview''' displays sample data until you run the VI again. If the cutoff frequency values are invalid, '''Result Preview''' does not display valid data.
|}

=== Block Diagram Inputs ===
{| class="wikitable"
! Parameter
! Description
|-
! Operand 1
| Specifies the first input for comparison.
|-
! Operand 2
| Specifies the second signal input for comparison. This input is available only when you select '''Second signal input''' in the configuration dialog box.
|-
! Constant Value to Compare Against
| Specifies the constant value with which to compare the '''Operand 1''' input. If '''Constant Value to Compare Against''' is not wired, the VI uses the '''Value''' specified in the configuration dialog box.
|-
! error in
| Describes error conditions that occur before this node runs.
|}

=== Block Diagram Outputs ===
{| class="wikitable"
! Parameter
! Description
|-
! Result
| Returns the resulting data based on the configuration of the Express VI.
|-
! error in
| Contains error information. This output provides standard error out functionality.
|}

== History ==
{{ambox|text=History information is needed. What changes have occurred over previous versions?}}
{| class="wikitable"
! Version
! Change(s)
|-
|[[File:LV2018.png|frameless|border|64x64px|LabVIEW 2018|link=LabVIEW 2018]]
|More info to come.
|}
== See Also ==
{{ambox|text=Add links to internal resources that would also help.}}

== External Links ==
{{ambox|text=Add links to external resources that would also help.}}

[[Category:Comparison Palette]]

Comparison function - Revision history

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