1D array of waveforms to single waveform
I'm got a continuous data application which results in an output of a
1D array of waveforms. This is done because the VI reads the
waveform out of the buffer at certain intervals in a loop, which
seems to be the only way to acquire data in a continuous mode at high
speed off of a non NI card, as reccomended by the manufacturer,
Measurement Computing. The waveforms are passed out of the loop,
becoming a 1D array of waveforms. I need to append the array
elements to one another (waveforms) to end up with a single waveform to
ease the latter processing. I'd prefer to do this using the time
stamps to make sure there are no misalignments, but I'd settle for a
simple method to append them to one another.
I've tried using the append waveform VI in a loop with what I thought
was appropriate logic, but I always seem to end up with just a portion
of the original data. Help is greatly appreciated. FYI I'll be
out of the office until Tues, so I won't be using info this until
then. - Thanks.
How exactly are you using the Append Waveform in a loop? Using it in a for loop like in the attached picture should work.
Attachments:
Append Waveforms.JPG 8 KB
Similar Messages
-
User event for array of waveforms with attribute
I have been transferring data in a Producer/Consumer architecture via User Events. The data consisted of an array of waveforms. When I added an attribute to the waveforms the code breaks with two errors about Create User Event: User event data type is unnamed or has elements with no names or duplicate names, and Contains unwired or bad terminal.
From reading the help on user events it is not clear that arrays are even allowed: "user event data type is a cluster of elements or an individual element whose data type and label define the data type and name of the user event."
From experimentation it seems that arrays of numerics and arrays of wavefroms without attributes work. A single waveform with an attribute can also be used. But an array of the same waveform with attribute leads to a broken run arrow. It also appears that I can put the array of waveforms with attributes inside a cluster and then create the user event.
Is this a bug, an undocumented corner case, or some "feature" that I do not understand?
Searching for User Event for Array of Waveforms generates some interesting, but mostly irrelevant results.
Lynntst wrote:
Another option would be typecasting, but it looks like you can't typecast a waveform. Variant to Data or Coerce to Type might also work, but I haven't tried.
I have also done the Flatten To String and Unflatten From String to send data around. It would be preferable to not need to do that though.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines -
Shifter register for array of waveforms
Hi guys,
I was trying to use shift register to append waveforms from multiple channels to their previous waveforms correspondingly.
The problem is when I click the stop button on the front panel and saved the data, the data file contains nothint except for some words like "waveform","t0", and "dt".
The attachment is the image of my VI.
Thanks!
Jude
Attachments:
screencap3.png 101 KBYour problem is your FOR loop at the bottom. When you first call this VI, the shift register will have the default value for the data type. In this case it will be an empty array of waveforms. A FOR loop will iterate the smallest of the size of the smallest autoindexing input array or the N. Well, the smallest will be 0 because of that empty array. So the FOR loop actually does not run at all. It just outputs an empty array. What you need to do is put a case structure around that FOR loop. When the loop index of the WHILE loop is 0 (first time reading anything) set the output to the waveform you just read. If the loop index is greater than 0 run the FOR loop like you have now.
If you look at the VI I gave you here you will see what I mean.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines -
How do i change 2 row of array into waveform with delta time and time
Hello,
How do i change 2 row of array into waveform with delta time and time
so the waveform graph will display two waveform,
waveform, not cluster =]
and how to extract 1d array from waveform?Hi AxE,
Here is an example VI, that do what You asked for.
Both requests.
Hope it Helps...
Attachments:
2D_to_Waveform.vi 75 KB -
Lowpass filtering an array of waveforms with different cutoff frequencies
I'm trying to take an array of waveforms and have seperate filter settings for each individual waveform. For example, I want to have a 2 hz cutoff frequency on my thermocouple inputs and a 100 hz cutoff frequency on a strain gage input.
When I try to accomplish this using the Butterworth filter (as shown in the image) I get weird results. The VI seems to be setup to only handle 1 waveform at a time. If I set the init/cont to F for init, the beginning of each waveform segment is reset to 0 which wrecks the data files. If I set the init/cont to "T" for continuous, the data is completely wrecked because the waveforms are interferring with each other. Clearly this VI is not setup for muliple instances (for use in a for loop).
There are the Waveform filters, but I seem to only be able to use 1 cutoff frequency for the entire set of waveforms.
In the subVI image below, I input an array of waveforms into a for loop with the settings collection for each channel (element in the waveform array). I pass the cutoff frequency to the butterworth filter with the Y data array from the segment of the waveform. Waveform data is supplied continuously (I need a live data filter).
Thanks for your input.
Attachments:
Filter applied to multiple waveforms.png 17 KBYou are correct (about the true/false on the cont/init input). Not sure I follow what the help is saying to do...
Is there anyway to verify the number of instanced "Filter Duplicates" are running? I'm still having a lot of issues with my implimentation and I'm wondering if I'm not initializing everything correctly. I've even added a button that should push a new re-initialization. I'm trying to have an interface that allows the user to turn off and on the filter while data is be aquired. Here is some of my code that I'm using to try and accomplish that, but after I've enabled the filter on multiple waveforms and hit my "re-initialize" button I still get bizarre data artifacts (like spikes) that would not be indicative of data on the other side of a low pass filter. Thanks for any additional feedback.
I've modified your Filter Duplicate to have an "Enable" feature so that the waveforms that I do not want any filtering of are just passed through.
I've tried to re-create the functionality of your Test multi-filter VI Server, but with the added boolean option to not have the filter performed:
So when "True" is on init/cont input the VI is re-open by VI server and the true signal propagates to the Filter Duplicate Asynchronous call. Here is a snippit from my main window call:
Lastly, here is the noisy data I'm dealing with:
Here is the data after I apply a 5Hz filter to each one:
Clearly data from one is being imposed on the other. Hitting my "re-initialize" button to send a "true" signal through doesn't fix it. How can I verify that my filters are working independently as desired?
Thanks! -
Pointer Manipulation: Wrap Around/Rollover/Rotation of LabVIEW Arrays and Waveforms???
I know we can't use pointers in LabVIEW, but I was wondering if there's any way we can do wrap-around [or "rollover," or "rotation"] of Array [or Waveform] values without having to make copies of the Array [or Waveform]?
For instance, suppose I'm reading one second's worth of data into a five second buffer. After the first five seconds, I've got
1st (1/5)th: 1st second's worth of data
2nd (1/5)th: 2nd second's worth of data
3rd (1/5)th: 3rd second's worth of data
4th (1/5)th: 4th second's worth of data
5th (1/5)th: 5th second's worth of data
Now I read the sixth second's worth of data, and overwrite the [original] first second, so that I have
1st (1/5)th: 6th second's worth of data
2nd (1/5)th: 2nd second's worth of data
3rd (1/5)th: 3rd second's worth of data
4th (1/5)th: 4th second's worth of data
5th (1/5)th: 5th second's worth of data
and in C, or C++, I'd just move the pointer up to the second (1/5)th of data, and start from there.
The LabVIEW Complex FFT is another place where this would be really useful. The Help File for the Complex FFT is in
Help | VI and Function Reference | Analyze VIs | Signal Processing VIs | Frequency Domain VIs | Complex FFT.
If you read the Help File, you see that LabVIEW returns an FFT with values in the range
[0, 2n - 1)
rather than the standard
[-n, n - 1)
i.e. LabVIEW takes the negative frequencies and tacks them on at the end, after the positive frequencies.
I'd like to be able to view my FFTs with the negative frequencies where they're supposed to be [i.e to the left of zero], and this would be SO easy if I could just move the underlying data pointer of the Waveform forward to the halfway point.
But, of course, in LabVIEW, I don't have pointers, so I was wondering: Are there any built-in VIs for Array [or Waveform] manipulation that will perform this sort of wrap-around [or "rollover," or "rotation"] of the data? If so, I couldn't find them. Ideally, such a VI would have two inputs: {old Array, new starting point}, and one output: {new Array}. Similarly with Waveforms, only you'd need to manipulate t0 as well.
Or do I have to copy the entire data set to a new Array [or Waveform] each time I reach the end of the buffer?
Thanks!> Ideally, such a VI would have two inputs: {old Array, new starting point}, and one output: {new Array}.
Have a look at "rotate 1D array" in the array palette (second row, fourth column).
(Sorry, I dont use waveform data).
LabVIEW Champion . Do more with less code and in less time . -
The attached file is work inprogress, with some dummy data sp that I can test it out without having to connect to equipment.
The second tab is the one that I am having the problem with. the output array from the replace element appears to be starting at the index position of 1 rather than 0 but that is ok it is still show that the new data is placed in incrementing element locations. However the main array that I am trying to build that is suppose to take each new calculation and place it in the next index(row) does not ap
pear to be working or at least I am not getting any indication on the inidcator.
Basically what I am attempting to do is is gather some pulses from adevice for a minute, place the results for a calculation, so that it displays then do the same again the next minute, but put these result in the next row and so on until the specifiied time has expired and the loop exits. I need to have all results displayed and keep building the array(display until, the end of the test)Eventually I will have to include a min max section that displays the min and max values calculated, but that should be easy with the min max function.Actually I thought this should have been easy but, I gues I can not see the forest through the trees. Can any one help to slear this up for me.
Attachments:
regulation_tester_7_loops.vi 244 KBI didn't really have time to dig in and understand your program in depth,
but I have a few tips for you that might things a bit easier:
- You use local variables excessively which really complicates things. Try
not to use them and it will make your life easier.
- If you flowchart the design (very similar to a dataflow diagram, keep in
mind!) you want to gather data, calculate a value from that data, store the
calculation in an array, and loop while the time is in a certain range. So
theres really not much need for a sequence as long as you get rid of the
local variables (sequences also complicate things)
- You loop again if timepassed+1 is still less than some constant. Rather
than messing with locals it seems so much easier to use a shiftregister (if
absolutely necessary) or in this case base it upon the number of iterations
of the loop. In this case it looks like "time passed" is the same thing as
the number of loop iterations, but I didn't check closely. There's an i
terminal in your whileloop to read for the number of iterations.
- After having simplified your design by eliminating unnecessary sequence
and local variables, you should be able to draw out the labview diagram.
Don't try to use the "insert into array" vis since theres no need. Each
iteration of your loop calculates a number which goes into the next position
of the array right? Pass your result outside the loop, and enable indexing
on the terminal so Labview automatically generates the array for you. If
your calculation is a function of previous data, then use a shift register
to keep previous values around.
I wish you luck. Post again if you have any questions. Without a more
detailed understanding of your task at hand it's kind of hard to post actual
code suggestions for you.
-joey
"nelsons" wrote in message
news:[email protected]...
> how do I create a 1d array that takes a single calculation and insert
> the result into the first row and then the next calculation the next
> time the loop passes that point and puts the results in thsecond row
> and so on until the loop is exited.
>
> The attached file is work inprogress, with some dummy data sp that I
> can test it out without having to connect to equipment.
> The second tab is the one that I am having the problem with. the
> output array from the replace element appears to be starting at the
> index position of 1 rather than 0 but that is ok it is still show that
> the new data is placed in incrementing element locations. However the
> main array that I am trying to build that is suppose to take each new
> calculation and place it in the next index(row) does not appear to be
> working or at least I am not getting any indication on the inidcator.
>
> Basically what I am attempting to do is is gather some pulses from
> adevice for a minute, place the results for a calculation, so that it
> displays then do the same again the next minute, but put these result
> in the next row and so on until the specifiied time has expired and
> the loop exits. I need to have all results displayed and keep building
> the array(display until, the end of the test)Eventually I will have to
> include a min max section that displays the min and max values
> calculated, but that should be easy with the min max function.Actually
> I thought this should have been easy but, I gues I can not see the
> forest through the trees. Can any one help to slear this up for me. -
New to Graphics, trying to display array output in a single window
I am trying to figure out how to use the GUI components of JAVA.
What I am trying to do is take my packaged array output and list it in a single window. All that ever prints is last array data set. The last keeps overwritting the previous. How do I keep the previous data shown while listing the next in the array?
Below are my three classes. The Frame Class is the class containing the display method. It is called near the bottom of the Product Class.
Product.java
// Inventory Program Part 4
/* This program will store multiple entries
for office supplies, give the inventory value,
sort the data by Product Name,
and output the results using a GUI */
import javax.swing.text.JTextComponent;
import javax.swing.JLabel;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JOptionPane; //Uses class JOptionPane
import java.util.Scanner; //Uses class Scanner
import java.util.Arrays; //Uses class Arrays
public class Product
private String productBrand[]; // Declares the array
public void setProductBrand( String brand[] ) // Declare setProductBrand method
productBrand = brand; // stores the productbrand
} // End setProductBrand method
public String getProductBrand( int counter ) // Declares getProductBrand method
return productBrand[ counter ]; // Returns data using counter to define the element
} // End method getProductBrand
public double restockingFee( double value ) // Declares restocking Fee method
double fee = 0; // Declares variable fee
fee = value * 0.05; // Calculates the sum of values
return fee; // Returns the restocking fee
} // End method restockingFee
public String inventoryValue( double value[] , int number, String name[] ) // Declares inventoryValue method
OfficeSupplies myOfficeSupplies = new OfficeSupplies(); //Creates OfficeSupplies Object
Product myProduct = new Product();
double total = 0; // Declares variable total
for ( int counter = 0; counter < number ; counter++ )
total += ( value[ counter ] + myProduct.restockingFee( value[ counter ] ) ); // Calculates the sum of values
return String.format( "%s$%.2f", "Total Inventory Value: " , total ); // Returns the total value
} // End method inventoryValue
// main method begins execution
public static void main( String args[] )
Scanner input = new Scanner( System.in ); //Creates Scanner object to input from command window
Product myProduct = new Product(); //Creates Product object
OfficeSupplies myOfficeSupplies = new OfficeSupplies(); //Creates OfficeSupplies Object
//Prompt for maxNumber using JOptionPane
String stringMaxNumber =
JOptionPane.showInputDialog( "Enter the number of products you wish to enter" );
int maxNumber = Integer.parseInt( stringMaxNumber );
String prodName[] = new String[ maxNumber ]; // Declares prodName array
int numberUnits[] = new int[ maxNumber ]; // Declares maxNumber array
float unitPrice[] = new float[ maxNumber ]; // Declares unitPrice array
double value[] = new double[ maxNumber ]; // Declares value array
String brand[] = new String [ maxNumber ]; // Declares brand array
String stringNumberUnits[] = new String [ maxNumber]; // Declares array
String stringUnitPrice[] = new String [ maxNumber ]; // Declares array
int productNumber[] = new int[ maxNumber ]; // Declares array
for ( int counter = 0; counter < maxNumber; counter++ ) // For loop for the number of products to enter
productNumber[ counter ] = counter;
myOfficeSupplies.setProductNumber( productNumber ); // Sends the Product name to method setProductNumber
//Prompt for product name using JOptionPane
prodName[ counter ] =
JOptionPane.showInputDialog( "Enter the Product Name" );
myOfficeSupplies.setProductName( prodName ); // Sends the Product name to method setProductName
//Prompt for brand name using JOptionPane
brand[ counter ] =
JOptionPane.showInputDialog( "Enter the Brand name of the Product" );
myProduct.setProductBrand( brand ); // Sends the Brand name to method setProductBrand
//Prompt for number of units using JOptionPane
stringNumberUnits[ counter ] =
JOptionPane.showInputDialog( "Enter the Number of Units" );
numberUnits[ counter ] = Integer.parseInt( stringNumberUnits[ counter ] );
myOfficeSupplies.setNumberUnits( numberUnits ); // Sends the Number Units to the method setNumberUnits
//Prompt for unit price using JOptionPane
stringUnitPrice[ counter ] =
JOptionPane.showInputDialog( "Enter the Unit Price" );
unitPrice[ counter ] = Float.parseFloat( stringUnitPrice[ counter ]);
myOfficeSupplies.setUnitPrice( unitPrice ); // Sends the Unit Price to the method setUnitPrice
value[ counter ] = numberUnits[ counter ] * unitPrice[ counter ]; // Calculates value for each item
myOfficeSupplies.setProductValue( value ); // Sends the product value to the method setProductValue
Arrays.sort( prodName, String.CASE_INSENSITIVE_ORDER ); // Calls method sort from Class Arrays
Frame myFrame = new Frame();
myFrame.displayData( myProduct, myOfficeSupplies, maxNumber );
// Outputs Total Inventory Value using a message dialog box
JOptionPane.showMessageDialog( null, myProduct.inventoryValue( value, maxNumber, prodName ),
"Total Inventory Value", JOptionPane.PLAIN_MESSAGE );
} // End method main
} // end class ProductOfficeSupplies.java ----> This is the data container
// Inventory Program Part 4
/* Stores the array values */
public class OfficeSupplies // Declaration for class Payroll
private int productNumber[];
public void setProductNumber( int number[] ) // Declare setProductNumber method
productNumber = number; // stores the product number
} // End setProductNumber method
public int getProductNumber( int counter ) // Declares getProductNumber method
return productNumber[ counter ];
} // End method getProductNumber
private String productName[];
public void setProductName( String name[] ) // Declare setProductName method
productName = name; // stores the Product name
} // End setProductName method
public String getProductName( int counter ) // Declares getProductName method
return productName[ counter ];
} // End method getProductName
private int numberUnits[];
public void setNumberUnits( int units[] ) // Declare setNumberUnits method
numberUnits = units; // stores the number of units
} // End setNumberUnits method
public int getNumberUnits( int counter ) // Declares getNumberUnits method
return numberUnits[ counter ];
} // End method getNumberUnits
private float unitPrice[];
public void setUnitPrice( float price[] ) // Declare setUnitPrice method
unitPrice = price; // stores the unit price
} // End setUnitPrice method
public float getUnitPrice( int counter ) // Declares getUnitPrice method
return unitPrice [ counter ];
} // End method getUnitPrice
private double productValue[];
public void setProductValue( double value[] ) // Declare setProductValue method
productValue = value; // stores the product value
} // End setProductValue method
public double getProductValue( int counter ) // Declares getProductValue method
return productValue[ counter ];
} // End method getProductValue
} // end class OfficeSuppliesFrame.java ------> Contains the display method
import java.awt.Color;
import javax.swing.text.JTextComponent;
import javax.swing.JLabel;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JOptionPane; //Uses class JOptionPane
public class Frame extends JFrame
public Frame() //Method declaration
super( "Products" );
} // end frame constructor
public void displayData( Product myProduct, OfficeSupplies myOfficeSupplies, int maxNumber )
//Here I attempted to use an array to output all of the array data in a single window
// JTextArea myTextArea[] = new JTextArea[ maxNumber ]; // Declares myTextArea array to display output
JTextArea myTextArea = new JTextArea(); // textarea to display output
// For loop to display data array in a single Window
for ( int counter = 0; counter < maxNumber; counter++ ) // Loop for displaying each product
// myTextArea[ counter ].setText( packageData( myProduct, myOfficeSupplies, counter ) + "\n" );
// add( myTextArea[ counter ] ); // add textarea to JFrame
myTextArea.setText( packageData( myProduct, myOfficeSupplies, counter ) + "\n" );
add( myTextArea ); // add textarea to JFrame
} // End For Loop
setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
setSize( 450, maxNumber*400 ); // set frame size
setVisible( true ); // display frame
public String packageData( Product myProduct, OfficeSupplies myOfficeSupplies, int counter ) // Method for formatting output
return String.format( "%s: %d\n%s: %s\n%s: %s\n%s: %s\n%s: $%.2f\n%s: $%.2f\n%s: $%.2f\n%s: $%.2f",
"Product Number", myOfficeSupplies.getProductNumber( counter ),
"Product Name", myOfficeSupplies.getProductName( counter ),
"Product Brand",myProduct.getProductBrand( counter ),
"Number of Units in stock", myOfficeSupplies.getNumberUnits( counter ),
"Price per Unit", myOfficeSupplies.getUnitPrice( counter ),
"Total Value of Item in Stock is", myOfficeSupplies.getProductValue( counter ),
"Restock charge this product is", myProduct.restockingFee( myOfficeSupplies.getProductValue( counter ) ),
"Total Value of Inventory plus restocking fee", myOfficeSupplies.getProductValue( counter )+
myProduct.restockingFee( myOfficeSupplies.getProductValue( counter ) ) );
} // end method packageData
}Lets pretend that your assignment was to manage a list of employees of a store, and that each employee is identified by their name, position, and hourly wage. If you created a program along the lines of your current product program, I picture you creating three separate ArrayLists (or arrays), one for each variable, something like this:
import java.util.ArrayList;
public class MyEmployees1
private ArrayList<String> names = new ArrayList<String>();
private ArrayList<String> positions = new ArrayList<String>();
private ArrayList<Double> hourlyWages = new ArrayList<Double>();
public void add(String name, String position, double wage)
names.add(name);
positions.add( position);
hourlyWages.add(wage);
public void removed()
// TODO: I am nervous about trying to manage this!
//.......... more
}This program tries to manage three separate parallel arrays (arraylists actually). They are parallel because the 3rd item in the names list corresponds to the 3rd item in the positions list and also the hourlywages list. If I wanted to delete data, I'd have to be very careful to delete the correct item in all three lists. If I tried to sort one list, I'd have to sort the other two in exactly the same way. It is extremely easy to mess this sort of program up.
Now lets look at a different approach. Say we created a MyEmployee class that contains the employee's name, position, and wage, along with the appropriate constructors, getters, setters, toString method, etc... something like so:
import java.text.NumberFormat;
public class MyEmployee
private String name;
private String position;
private double hourlyWage;
public MyEmployee(String name, String position, double hourlyWage)
this.name = name;
this.position = position;
this.hourlyWage = hourlyWage;
public String getName()
return name;
public String getPosition()
return position;
public double getHourlyWage()
return hourlyWage;
public String toString()
// don't worry about these methods here. They're just to make the output look nice
NumberFormat currency = NumberFormat.getCurrencyInstance();
return String.format("Name: %-15s Position: %-15s Wage: %s",
name, position, currency.format(hourlyWage));
}Now I can create a MyEmployees2 class that holds a single list of MyEmployee objects, like so:
import java.util.ArrayList;
public class MyEmployees2
private ArrayList<MyEmployee> employeeList = new ArrayList<MyEmployee>();
public boolean add(MyEmployee employee)
return employeeList.add(employee);
public boolean remove(MyEmployee employee)
return employeeList.remove(employee);
public void display()
for (MyEmployee employee : employeeList)
System.out.println(employee);
public static void main(String[] args)
MyEmployees2 empl2 = new MyEmployees2();
empl2.add(new MyEmployee("John Smith", "Salesman", 20));
empl2.add(new MyEmployee("Jane Smyth", "Salesman", 25));
empl2.add(new MyEmployee("Fred Flinstone", "Janitor", 15));
empl2.add(new MyEmployee("Barney Rubble", "Supervisor", 35));
empl2.add(new MyEmployee("Mr. Spacely", "The Big Boss", 45));
empl2.display();
}Now if I want to add an Employee, I only add to one list. Same if I want to remove, only one list, and of course, the same for sorting. It is much safer and easier to do things this way. Make sense? -
Best way to pass an array of waveforms inbetween VIs
In my VI I am developing I have multiple data sources that output a single waveform. I group these waveforms togeather to make a wave form array. The user selects which waveform they would like to display and they are displayed on a graph on a different form. Right now I have each different graph VI generating the whole array and displaying the selected element.
My question is, this seems to be not efficent because I am generating data in 3 spots. I would think it would be better to generate it in one spot and then pass only the need data to the three graph VIs. What is the best way todo this? A global variable? Queue? Any suggestions?You're probably tired of hearing me say this, but the global function idea is the best.
A global variable makes a COPY of the data each time you read it. That takes time, and memory. If each of 3 window reads the global, and picks out a channel, then you've made 3 copies of the original data. Depending on your data size, that may or may not be a problem.
A queue means that once you read the data, it's lost from the queue. If window A reads from the queue, that data chunk is not in the queue any longer, so Window B can't read that same data.
If the main window generates the data and deposits it in a global function, then each window can ask the global function for a specific channel to display.
DATA STORAGE.vi:
Inputs:
WRITE/read (bool
ean)
DATA IN (2-D array of DBL, for example)
Channel Index (I32)
Outputs:
DATA OUT: 1-D array of DBL (or waveform, maybe).
Code:
WHILE
If WRITE/read
Store DATA IN in a shift reg.
else
Pass Shift reg IN to Shift reg Out.
Pick out channel via CHANNEL INDEX
Pass selected data to DATA OUT.
Loop NEVER.
The purpose of the loop is just to have a shift reg. It doesn't really loop - it executes once per call.
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks -
Plotting elements from an array in waveform chart
Hi all,
I am trying to plot a real time data by extracting single element from an array.
Problem is that, at some frequencies waveform chart plot perfect while at other frequencies it plots like a undersampled signals.
Any suggestions?
Attachments:
wfm.png 136 KB
wfm.vi 133 KBThe timing information comes from the data acquisition process, not the display. You should be able to get equally good display of timing information on a chart or a graph.
How many samples do you read at a time? How do you define "realtime"? Anything plotted on a graph or chart for the use of a human operator does not need to be updated more than about 10 times per second because the eye/mind system works at about that time scale. For humans a real time grahical update rate of 2 to 10 Hz is adequate. Then you will have 256 to ~51 new samples at each update.
Another issue is that both your graph and your plot have plot areas which are less than 200 pixels wide. If you supply more than [plot width] pixels to a graph or chart, LabVIEW will reduce the data to determine which pixels to plot. So your graph with 1000 X-axis values has that reduced to the 184 pixels across the width of the graph. So, regardless of the precision of the data, the "precision" of the display is limited to the number of pixels.
Lynn -
How do I plot an array of waveforms?
The computer on which I am building my VI doesn't have access to the internet, so I can't post any of my code (so I'll use as much detail as possible)
I am taking DAQ measurements for four devices that come in as (I believe) an array of dynamic data type. I split the signal and I have each channel outputting its own dynamic data type. After a user-specified time interval, a timed while loop will trigger the DAQ to take a measurement and write the data to a file and plot the data. The file writing was easy, but I am stuck on the plotting aspect.
What I have: Since efficiency won't be an issue (~15 minute average time delay), I have created a shift register of dynamic data type. Each iteration of the while loop, I append the newly acquired data to an array of dynamic data using the BuildArray function. I need to be able to take this and plot it in a graph, but every time I try it tells me that the dimensions of the source and sink don't match. Also, I need to do this for each of the four sets of data (and put them on the same plot).
What can I do to get plottable data from my shift register?
I cannot open .VI files, so I would really appreciate it if I could get responses in pictures of block diagrams or text. Thanks.
Solved!
Go to Solution.Hi nc61,
stay away from DDT (dynamic datatype) and you will be fine. Especially when trying to collect data by building up arrays of DDT (which probably isn't doing what you really want)...
- Use DAQmxRead to get either arrays of data or waveform(s). Use BuildArray for simple data or waveform functions for waveforms to collect data in shift register. Plotting will be easy with those data!
- There's the well-known example finder in LabVIEW's help menu. Try it...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome -
Dear All,
I have the following problem, if anybody can help I will be more than
grateful.
I have a signal generator to create sine waves and in my vi I am using
Analog Input vi (configure, start, read vi ) to acquire this sine wave.
I know I can have the voltage values and time information written in a
text file, but I want to get them in the vi and use the time
information to trigger an other event. Using a for loop and creating
time values are not helpful since the timing is critical for an other
event.
When I wire the waveform output from the Read vi to "Get waveform time
array.vi" or "Waveform to XY pairs" it is giving me a "You have
connected an array to its element type" error. I am guessing the Analog
Read vi thinks that there are several waveforms.
Using index array.vi helps fix broken wire between Analog Read.vi and
Get Waveform Time .vi but it does not allow getting true data from Get
Waveform Time Array.vi. I mean all the time array is filled with 3.224
E+9. My vi is attached. Same case is true for also Waveform to XY
Pairs.vi. I mean all of the xy pairs are same and some funny numbers.
Anyway here is my vi:
http://ilter.gercek.info/time.vi
Thank you very much for your help.
Best wishes,
ilterTime stamps are the number of seconds since 12:00 a.m., Friday, January 1, 1904. And, 3.224E9 is a
bit over 102 years. You can use the functions on the Timing palette to
get these numbers into something a little more meaningful. -
Combining two StringBuffer array elements into a single array element
I just need to know how to combine two stringBuffer array elements into one
StringBuffer ciphertext [] = new StringBuffer[2];
StringBuffer s0 = new StringBuffer("11011111111110001001101110110101");
StringBuffer s1 = new StringBuffer("00010011001101000101011101111001");
ciphertext[0] = s0;
ciphertext[1] = s1;
ciphertext[2] = ciphertext[0].append(ciphertext[1]);I get an array index out of bounds exception:2
ThanksStringBuffer ciphertext [] = new StringBuffer[3]; // legal index values are: 0,1,2
-
Problem passing multiple array lists to a single method
Hi, all:
I have written a generic averaging method that takes an array list full of doubles, adds them all up, divides by the size of the array list, and spits out a double variable. I want to pass it several array lists from another method, and I can't quite figure out how to do it. Here's the averager method:
public double averagerMethod (ArrayList <Double> arrayList) {
ArrayList <Double> x = new ArrayList <Double> (arrayList); //the array list of integers being fed into this method.
double total = 0;//the total of the integers in that array list.
for (int i = 0; i < x.size(); i++) {//for every element in the array list,
double addition = x.get(i);//get each element,
total = total + addition; //add it to the total,
double arrayListSize = x.size();//get the total number of elements in that array list,
double average = total/arrayListSize;//divide the sum of the elements by the number of elements,
return average;//return the average.
}And here's the method that sends several array lists to that method:
public boolean sameParameterSweep (ArrayList <Double> arrayList) {
sameParameterSweep = false;//automatically sets the boolean to false.
arrayList = new ArrayList <Double> (checker);//instantiate an array list that's the same as checker.
double same = arrayList.get(2); //gets the third value from the array list and casts it to double.
if (same == before) {//if the third value is the same as the previous row's third value,
processARowIntoArrayLists(checker);//send this row to the parseAParameterSweep method.
sameParameterSweep = true;//set the parameter sweep to true.
if (same != before) {//if the third value is NOT the same,
averagerMethod(totalTicks);//go average the values in the array lists that have been stored.
averagerMethod(totalNumGreens);
averagerMethod(totalNumMagentas);
sameParameterSweep = false;
before = same; //problematic!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
return sameParameterSweep;
}Obviously, the problem is that I'm not passing the array lists from this method to the averager method the right way. What am I doing wrong?Encephalopathic wrote:
There are several issues that I see, but the main one is that you are calculating average results but then just discarding them. You never assign the result to a variable.
In other words you're doing this:
averagerMethod(myArrayList); // this discards the resultinstead of this:
someDoubleVariable = averagerMethod(myArrayList); // this stores the resultAlso, do you wish to check for zero-sized array lists before calculating? And what would you return if the array list size were zero?So in solving that problem, I've come up with another one that I can't figure out, and I can't fix this problem until I fix that.
I have several thousand lines of data. They consist of parameter sweeps of given variables. What I'm trying to do is to store pieces of
data in array lists until the next parameter adjustment happens. When that parameter adjustment happens, I want to take the arraylists
I've been storing data in, do my averaging thing, and clear the arraylists for the next set of runs under a given parameter set.
Here's the issue: I'm having the devil of a time telling my application that a given parameter run is over. Imagine me doing stuff to several variables (number of solders, number of greens, number of magentas) and getting columns of output. My data will hold constant the number of soldiers, and for, say, ten runs at 100 soldiers, I'll get varying numbers of greens and magentas at the end of each of those ten runs. When I switch to 150 soldiers to generate data for ten more runs, and so forth, I need to average the number of greens and magentas at the end of the previous set of ten runs. My problem is that I can't figure out how to tell my app that a given parameter run is over.
I have it set up so that I take my data file of, say, ten thousand lines, and read each line into a scanner to do stuff with. I need to check a given line's third value, and compare it to the previous line's third value (that's the number of soldiers). If this line has a third value that is the same as the previous line's third value, send this line to the other methods that break it up and store it. If this line has a third value that is NOT the same as the previous line's third value, go calculate the averages, clear those array lists, and begin a new chunk of data by sending this line to the other methods that break it up and store it.
This is not as trivial a problem as it would seem at first: I can't figure out how to check the previous line's third value. I've written a lot of torturous code, but I just deleted it because I kept getting myself in deeper and deeper with added methods. How can I check the previous value of an array list that's NOT the one I'm fiddling with right now? Here's the method I use to create the array lists of lines of doubles:
public void parseMyFileLineByLine() {
totalNumGreens = new ArrayList <Double>();//the total number of greens for a given parameter sweep
totalNumMagentas = new ArrayList <Double>();//the total number of magentas for a given parameter sweep.
totalTicks = new ArrayList <Double>();//the total number of ticks it took to settle for a given parameter sweep.
for (int i = 8; i < rowStorer.size() - 2; i++) {//for each line,
checker = new ArrayList <Double>();//instantiates an array list to store each piece in that row.
String nextLine = rowStorer.get(i); //instantiate a string that contains all the information in that line.
try {
Scanner rowScanner = new Scanner (nextLine); //instantiates a scanner for the row under analysis.
rowScanner.useDelimiter(",\\s*");//that scanner can use whitespace or commas as the delimiter between information.
while (rowScanner.hasNext()) {//while there's still information in that scanner,
String piece = rowScanner.next(); //gets each piece of information from the row scanner.
double x = Double.valueOf(piece);//casts that stringed piece to a double.
checker.add(x);//adds those doubles to the array list checker.
catch (NoSuchElementException nsee) {
nsee.printStackTrace();
//System.out.println("checker contains: " + checker);
processARowIntoArrayLists(checker);//sends checker to the method that splits it up into its columns.
} -
How to efficiently create a single waveform based on data from two other waveforms?
I have a 1-D array of waveform with size = 4 that contain "raw" potentiometer voltage data. I need to manipulate waveform data from index 0 & 1 using the formula shown below to derive a single waveform of angle data. I need to do the same for index 2 & 3 as this is a redundant circuit. I was hoping that the formula node can work on entire arrays and although it can take an array as input, it requires me to index the array in the formula so it becomes a scalar value.
Since the formula is relatively complex, I'd like to keep it in text form but have it automatically work on each point of the two input arrays. This math is done inline with pulling data out of a DAQ and so I need it to be as efficient as possible so that I don't spend too much time on it and potentially overflow the DAQ buffer.
The naive solution would be to wrap the formula nodes with for loops, but I don't know if this is this is an efficient way to do this. I would appreciate any suggestions on how best to tackle this.
Thanks!
Solved!
Go to Solution.Here's how I would do it with no formula nodes or loops requied:
If you want to use the formula node, then you could run a loop inside each formula node while you index through the arrays. The performance difference between formula nodes and the graphical approach should be insignificant. Note that my approach assumes that the array sizes are the same. You could also create a sub VI to contain the math so you don't have to maintain two copies of the same piece of code.
Chris M
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