Graphing wait period in Case Structure

I have a VI that is outputting a wave to a linear actuator. The linear actuator should engage then wait a period of time.
Rightnowthetheprogramcurrentlyexecutestheoutput to the device butIwouldliketobeabletoseethewaitperiodonthegraph. It would be nice to have the wait period be at the new offset as well.
I have tired to wire a local variable to the graph inside the false structure however this did graph the pause.
The main VI is the Sinewave generating (KNS)X01 the other two are subVI's
Does anyone have any ideas!?
Thanks!
Attachments:
HR percent Systolic(SubVI).vi ‏13 KB
Amplitude and offset VI.vi ‏18 KB
SineWaveGenerating (KNS)X01.vi ‏48 KB

Hi kspink,
From your code, what I see is that it plots the waveform graph and waits. Graph is not ploted while it is waiting. I'm not sure what do mean by "butIwouldliketobeabletoseethewaitperiodonthegraph". Perhaps you could plot out in a diagram on what do you actually want to see?
Thanks
Warmest regards,
Lennard.C
Learning new things everyday...

Similar Messages

How do I select different graphs to show using case structure?

Hello,
I am working on a piece of code where I am getting data from 6 different sources (reading temperature & pH on 6 different tanks)... I am using
1) a case structure
2) while loop
3) waveform chart
Now, I want to have it so, the User selects which graph he wants to see (tank 1, tank 2, tank 3, etc...). And then, program ONLY SHOWS the graph for THAT TANK...
So I have an Event Structure with the "Tank #" control, which is supposed to change the graph that is on display. However, right now, it is not working.
Let's say I start the program..., then I click "Tank 1"... it graphs Tank 1... then I click "Tank 2"... instead of COMPLETLY CHANGING the graph, it CONTINUES to graph the data from TANK 2 on the same graph. I.E.:   it plots points 1 - 7 from TANK 1, then plots points 8 - 15 from TANK 2,.... on the same Graph.
I don't want that. I want it to change the graph.   But if I put the graph in the Case Structure, it puts multiple graphs on the Front Panel... How can I do it?
NOTE: Ignore case 3.   And each case should be corresponding to Tank #...
Thank your for reading--
Attachments:
GraphProblem_NI forum.vi ‏3166 KB

the easy answer is that you should clear your waveform graph before sending new data to it...
It's as easy as writing an empty array to it's property node Value...
But..
you've got much... much more cleaning up to do. Clearing the graph is just one thing.
Your code is unreadable. Why do you have 3 While Loops?
What does the bottom one do?
Why are you complicating things with cluster going into the queue? An enumerator would do the same trick.
Is this code going into a cRIO or cFieldpoint? If not, what's up with using Shared Variables? Are you planning to send data over the network?
Debugging this code will become a nightmare. Scalability will be worse..
I would recommend refactoring the code while it is still manageable.

Case Structure timing/ writing data to a excel

Hi all,
I have written a program that has the main functions of allowing the user to generate a random number between either 0-10 or 5-15 by using the labelled switch. I also have a control which can switch this function on or off. When this switch is true it will display the random number and also write this number to an excel spreadsheet every 1 second (I hope). When false this will stop displaying the number and hence not write the number to a file.
However, I am having the following issues:
1. Excel file is corrupt once I begin to write the generated numbers to the spreadsheet. (I am trying to write to a .xlsx file)
2. Once I begin to try write the numbers to file, the elapsed timer only displays the time is 1second intervals rather than the full time.
I changed the .xlsx file to a .csv file and this solved issue 1. but it only recorded one random number rather than the numbers that were generated in that time since switched on/off.
Should I have the write to spreadsheet function in the timed case structure?
Should the file path control be outside this case structure?
Have I set up the write to spreadsheet VI correctly?
If anyone could help with these issues that would be a big help.
Thanks!
Attachments:
Random Number tester.vi ‏30 KB

lneill65 wrote:
There is still an issue with the elapsed time. Once I begin I turn the top boolean control to true, the elapsed time begins changing at the set time increment inside the case structure. Is there anyway to stop this from happening?
Your elapsed time display is independent of the boolean switches because it is on the toplevel loop diagram. I am not sure why you place a five second wait inside the case structure if you want to write once per second.
I am not sure why you have two sequential case structures since the calculations of the first structure is not needed unless the other case is also true. Why not place it inside the true case?
You should also adhere to some basic coding styles. Avoid overlapping and floating objects, hidden wires, right-to-left wiring.
If it is sufficient if the code reacts once per second, just run the loop with a 1 second wait. If you don't want to display a stale random number if the switch is off, place the indicator after the case structure.
Here's a quick draft. Modify as needed. I probably would use an event structure, but let's keep it simple at this stage. You should also modify it so it does not try to write with an illegal path and also retain the selected path once selected. I propably would use a file dialog instead of a FP Path control.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
Random Number testerMOD.vi ‏9 KB

How to make wave graph restart when the condition of case structure is changed?

Exp: Condition of case structure a<b ( a: control, b: constant). A wavegraph puts inside a while loop , in True condition (a<b). How can I make the wave graph restart if a is changed?

Aren't you confusin waveform graph and waveform chart ? If this is the case, you can clear a chart using the History data property node, fed with an empty array.
Message Edité par chilly charly le 11-08-2007 01:57 PM
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...
Attachments:
Example_BD.png ‏1 KB

How can I pass data generated in a SubVI inside a Case Structure out of the Case Structure?

Hello,
I am using a USB 2701 to control a heater. I have three SubVIs that are all working properly on their own. I'd like to use an Enum to select which of the SubVIs is running at a given time. The problem is that no data is passing out of the case structure. How can I pass the temperatures and heater outputs acquired by the SubVIs to the main VI? I've attached my some of my code below. I can't attach more than 3 files, but you can see how the main VI is configured. Like I said, the SubVIs are working individually, so you shouldn't really need to look at them.
Thank you,
CJones581
Attachments:
RampHeater6-21-07.vi ‏305 KB
69_Heater_Case.vi ‏23 KB
HeaterTCD6-21-07.vi ‏210 KB

CJones,
You might check a couple of things.
Your HeaterTCD... VI has a While loop with a stop button condition. HeaterTCD pass out values only when it finishes running. If it doesn't pop open the front panel (which usually doesn't happen when running a SubVI) you could run into a stuck loop because you don't have access to the Stop button. This could appear in the form of no data being passed out (because the SubVI never stops running). The primary VI opens the HeaterTCD VI, starts it, and waits for the VI to finish and pass final values .
Secondary note: Unless you want your SubVI panel (which probably isn't open when running the main VI) to update continuously, consider moving your Temperature Graph and Temperature oC indicators outside the while loop. Pass final values to them via a tunnel, since the main VI will only read their values after the loop finishes running, anyway.
It might help to add error management to HeaterTCD like you have for RampHeater. If you connect error lines with Error Outs to your main VI, that will help tell if there is an error somewhere that is preventing info output.
RampHeater SubVI has the same issue with the stop button. It is also probably getting stuck in the While loop waiting for a manual push of that SubVI's Stop button.
An easy way to test this would be to set up a logic circuit so that when the While loop iteration counter reaches a certain number, it registers True and sends it to the conditional. I know this isn't what you want to do long-term, but if that lets your SubVI return outputs it means that the SubVI was just never stopping.
Hope that helps.
David C, Applications Engineering
David C
Applications Engineering

Execute Case Structure with Button Press Slows Down VI

Hi -
I'm fairly new to LabView, and I am having some issues with using a button to run a timed while loop.
I am writing a VI that outputs a timed voltage pulse to an output channel on a DAQ; meanwhile, the VI reads and graphs the voltage on three input channels on the DAQ. When I use a timed loop that automatically executes when the VI runs, the program works. However, I would like to include a button so I can control the timing and number of voltage pulses sent to the output channel, instead of sending only one voltage pulse each time the VI runs. I have tried to do this using a button wired to a case structure. If the button is 'true,' the VI should send the voltage pulse. If the button is 'false,' the VI should keep the voltage at zero.
When the button is 'false,' the VI runs normally; however, when the button changes to 'true,' the VI slows down and never sends the pulse. Why does this happen? How can I fix it?
Also, how can I send the voltage pulse only when the value of the button changes? I only want the timed loop to execute once when the button changes value.
Thanks for any help or advice!!!
Attachments:
Sensor Read6.vi ‏85 KB

The graph is in the same while loop as the case structure. The while loop won't iterate until all the code inside of it has completed. So the graph only gets updated once, and won't update again until the while loop iterates again. If you need more continual updating you may want to put that in a loop that executes a couple of times, or completely separate your code into 2 while loops. Is it that long of a wait considering your pulse length is 1 second?
Your analog output code is just writing a voltage out (7 volts) until it eventually writes out 0 volts. There is no reason for it to drop down unless you have some sort of electrical problem between your DAQ device and the device on the other end that is reading the 7 volts. What are you connecting that analog output too?
What if you don't use LabVIEW and try to test out that analog output using Measurement and Automation Explorer? Does it do the same thing?

Can I put a READ function in a TRUE/FALSE case structure?

Hi,
I have a vi that operates as controller for a mechanical system of motors. There are several sensors of various types, that provide input to the vi, including encoders, whose period is being measured. The attached vi is the encoder period measuring part. It measures 15 periods and tells me the average of the 15 with each loop iteration.
In my application, the encoder period measurement is not needed unless the vi knows that ALL THE OTHER sensors in the hardware configuration are measuring values within the desired range. For example, Sensors A, B and C should all measure between 5-10. If they are all showing values between 5-10, then, we want the encoder value to read and display. If only one of the sensors, say A, is measuring 12, then, we don't want the period value to READ or be subsequently processed. So, it is easy to set up the sensors A, B, C, to give a TRUE or FALSE based on whether they are within range or not, and if all 3 are TRUE, then, that value can easily be passed to the case structure that holds my READ function for the period. Is this a good way to do this? The goal is to eliminate unnecessary execution time that the period READ function would consume, as well as all subsequent calculations that are performed on the period value collected. The period data is of no use if any one of the other sensors is not in the correct range.
If any one of the other sensors is out of range, we want to skip the encoder READ step altogether. So, it is easy to structure a BOOLEAN in my vi as shown in the attachment. If I do it this way, will it throw an error, or just skip the READ until the BOOLEAN is true again? Is there a better way to prevent the READ from happening if one of my other sensor values is not within the correct range?
Thanks,
Dave
Solved!
Go to Solution.
Attachments:
forum JUly 18.vi ‏26 KB

Sure, you can put a Read inside a case structure. For your application, just check that your sensors are all within range (Comparisons palette), then AND the T/F's and use the result of that for your case structure. (If you are already doing the in-range check, I can't see it here because you have 5 subVIs that I cannot open here.
Cameron
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How to get a case structure to execute only once in a loop

I have a while loop that is monitoring temperature. Once the temperature meets or exceeds a given setpoint I want to start a timer. At this point I don't want to monitor the temperature anymore. That is, if the temperature should drop below the setpoint, I don't want to execute the case structure again when the temperture meets or exceeds the setpoint(the temp may oscillate about the setpoint for a given period of time). In any event, I need the case structure to execute only one time, not every iteration of the loop.

You can put a local Boolean variable "Flag" inside that case structure and
set "Flag" to False. Outside the case structure, use an "AND" function
output to control the case structure. The "AND" function has two inputs. One
goes to the comparison results between real temp and setpoint. The other
inputs connects to the "Flag" variable. In this way, once you entered that
case structure, the "Flag" will be turned to False, and then in next
iteration, you won't get into the case again because the "AND" function will
be False as your "Flag" is False now.
Hope this helps.
Rentian
1. Inside the case structure, put a
"BB Herman" wrote in message
news:[email protected]..
>I have a while loop that is monitori
ng temperature. Once the
> temperature meets or exceeds a given setpoint I want to start a timer.
> At this point I don't want to monitor the temperature anymore. That
> is, if the temperature should drop below the setpoint, I don't want to
> execute the case structure again when the temperture meets or exceeds
> the setpoint(the temp may oscillate about the setpoint for a given
> period of time). In any event, I need the case structure to execute
> only one time, not every iteration of the loop.

Multiple booleans controlling one boolean input for a case structure

Hello,
I have four boolean buttons and a case structure with a boolean input. I would like to write the program so that whenever any one of the four boolean button changes value, the case structure reads true for one loop interation, and then returns to false.
I have tried all sorts of things and can't seem to figure it out.
Ultimately, the ideal function of the program is so that whenever you push any one of the four boolean voltage controllers, that voltage case is chosen in the case structure, the time in seconds is written to a file, and the elapsed time timer is reset.
I have attached my program. Let me know if you have suggestions. Thanks.
Attachments:
Volt_Control_And_Time_Counter.vi ‏71 KB

Zappow wrote:
However, with this setup, the time counter still doesn't work.
The event structure for all four buttons has a true boolean constant connected to my file-saving case structure. If I connect this to my elapsed time express VI reset button, the timer doesn't count.
The timer does not count because you have not wired a timeout to the lower event structure. The default timeout is -1, so the lower loop never spins via timeout
It is useless to have a wait in a loop that also has a timeout case. Just wire an approriate timeout value to the timeout terminal and remove all waits. It is also not necessary to have a 1ms ttimeout if your timeout values only displays to 100ms resolution. Can you explain why you think you need two loops and all that extra code?
Attached is a quick rewrite that solves some of the problem. Since I don't have any hardware, I replace the voltage out with a meter.
You have way too many FP controls and indicators. Use arrays!
Let me know if yo have any questions. Modify as needed.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
Volt_Control_And_Time_CounterMOD.vi ‏63 KB

Why won't my charts continually update while running a case structure?

I'm making a VI to drive an actuator and read a force on a load cell. I have programmed the actuator to run through a flat sequence using millisecond timers to delay its drives outward and inward, which is necessary for its intended use. However, my goal is to have it display the motor position and the force on the load cell on the charts continuously throughout the test. However, when activating the case structure containing the test sequence, the graph fails to update live.
I'm not sure if I'm on the right track, but I have posed my file for whomever is interested. I hope you can lead me in the right direction, and thank you very much.
Keith Blume
Attachments:
Final VI.vi ‏303 KB

johnsold wrote:
You can find the version of a VI you have downloaded (as long as you have not saved it) by closing the window.
Well, closing the window is a bit drastic.
Simply go to VI-properties (e.g. by right-clicking the icon in the upper right) and do: "General...list unsaved changes"
Message Edited by altenbach on 12-16-2008 08:53 AM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
Version.png ‏31 KB

Trying to clear an array inside a case structure

Good morning all. I am trying (unsuccessfully, obviously) to clear an array inside a case structure. (See case structure at right side of vi, I colored it green to make it easy to find). Here's (briefly) what I'm trying to do. I have 6 test probes in the process. All six probes are connected to the Alcatel Detector through a 6-solenoid manifold. As I run the test, I want to sample 1/second, for let's say 3 minutes. For the first 30 seconds, I want to pull a sample from from probe 1, so I turn on solenoid one and leave it open for 30 seconds. Now all 30 values are tagged as having come from Probe 1, and they're stored in array 1. I can now compute an average value for probe 1. Then I close solenoid 1 and open solenoid 2, saving the next 30 values to array 2. (and so-on, until I have measured all 6 probes for 30 seconds each). Then I wait a pre-determined amount of time and repeat the process. Here's my problem. I want to clear out each array as I begin the second iteration, so that I can easily compute the average of the last 30 values. If I initialize the array by connecting a constant 0 to the shift register on the for loop insid ethe case structure, it does not work, nor does it work to place the 0 outide the overall for loop (the next for loop going out, NOT the OVERALL for loop). I know my programming skills are still crude, but I'm putting everything into this. Anyone have any suggestions?
Attachments:
HCMF rev 1 25 Apr.vi ‏485 KB

Altenbach, I definately understand your approach, and I like it much better than my own. But I still have no luck making it work. I get the same result as before (my original attempt). Value 0 of the array simply changes each iteration, with nothing "saved". Each new value simply overwrites the last value. Can you take a look at my new vi, with changes, and see if you can find the error of my ways. I am but a rookie Jedi in the vast reaches of LabVIEW Space, and you are no doubt a Jedi MASTER
Attachments:
HCMF rev 1 25 Apr pm.vi ‏374 KB

Event structure or case structure

I have some case structures wired to buttons. When each button is true, code inside the corresponding case structure executes. `What are the advantages/disadvantages of using an event structure instead of a case structure?
Ron Deavers, CLD

Place an indicator for the iteration terminal of the main loop to see an obvious difference
Your case structures must be in a loop that constanty runs. If you don't put a delay in the loop, it consumes all CPU, but if your delay is too long, it takes a moment to react to the button changes. The loop spins all the time, no matter if you press buttons or not.
Your event structure also sits in a loop, but nothing happens until you press a button. Now the event structure triggers IMMEDIATELY, executes the event case, and then waits for the next event. The loop does not spin unless needed.
You can even mix the functions by using a timeout event. Code in the timeout event occurs at regular intervals, but at any time, any of the other events can take over.
LabVIEW Champion . Do more with less code and in less time .

Cluster value lost when leaving case structure

Hello all,
I am having an issue with a particular VI I am working on. (FYI this is in Labview 8.0)
The VI is set up to run a current source, voltmeter, and thermometer and then record and graph data in various ways that are selectable by the user.
Everything seems to be working fine except one particular graphing method. When I try to graph Current vs. Voltage, the current value is gettiing lost. Within a case structure the current and voltage are combined into a cluster and then exit the case structre to be later appended to a cluster array.
However, the value of the cluster is being lost when the graph is set for Current vs. Voltage. Any other method and it is working properly.
I can't seem to figure out why this is happening as it does not make much sense that the other methods of graphing work but this one doesn't when it is coded the exact same other than having different variables.
I have attached the VI with added indicators showing that the cluster value is being lost once it exits the case structure. Any help would be much appreciated.
Thank you very much and I apologize for my extremely messy VI.
- Nathan Cernetic
Solved!
Go to Solution.
Attachments:
IV-RT.vi ‏185 KB

You really need to boil this down to something we can run and reproduce the issue.
Have you tried to break a few relevant connections and rewire? Maybe something is corrupt.
Beside being a mess, your VI has quite a few glaring mistakes.
Let's have a look at the structures in the upper right:
90% of the code is the same in all three case structures, so all that needs to be inside the case structure is the small part where you built the 2D array. Everything else belongs outside the case.
The sequence structure has no useful function.
Why do you need to reverse the array with each iteration of the small FOR loop? Once before the loop would be enough. Right?
Why do you use built array inside the small FOR loop, but don't autoindex at the loop boundary? All you ever get is an array with exactly one element, no matter how much the loop runs. Seems useless! (see below image for an alternative).
You would not even need to reverse if you would use "built array" instead of "insert into array at position 0" in the central part.
Others: You constantly hammer all your property nodes. The only need to be called when things change. Again, you have way too many instances. For example in the case structure where you are having problems, the same property nodes exist in all cases. A single instance of the property node belong outside the case and only the string constants inside each case. Whenever code is the same in all cases of a case structure, that code belongs outside!
Message Edited by altenbach on 06-19-2009 03:39 PM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
RubeLoopII.png ‏10 KB

Case structure is restarting at 120? should go to 167

My case structure is restarting at 0 when it gets to case 120 instead of continuing until 167? also, how can I get my vi to execute a certain case for x amount of time, i tried the wait vi but it just wait to execute instead of executing until time is up. I would appreciate any help, thanks.
Here is my prog.
Attachments:
version22.vi ‏1329 KB

If you go to case 120 you'll notice that you did not wire the ring to the output tunnel. Thus it will get reset to zero.
(Just right-click on the output tunnel and deselect "use defaut if unwired". Now click on the broken run arrow and search for the error about the missing tunnel assignment and double-click the error. It will get you to the error).
Your programming style is unbelievable tedious. Why don't you follow our advice and streamline your code. Is there anything in my last example that you don't understand?
LabVIEW Champion . Do more with less code and in less time .

Tab control with a case structure

I am having trouble getting my tab control to work with case structure. I have 4 tabs that i want displayed on my front panel, each with a separate graph. When I click on any tab besides the first one there is nothing shown on the graph. I think i have some wiring issues. Any ideas?
Attachments:
version1.vi ‏379 KB

See also this and this discusion. Most of the time, tab controls don't need any code.
(You also have a couple of breakpoints (one on the entire diagram and one on the while loop). Make sure you remove them. Look for the red outlines.
LabVIEW Champion . Do more with less code and in less time .

Graphing wait period in Case Structure

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