Case Structure Ranges Determined From Input Variables

Hello,
I am trying to write a vi that will read in a random number, and depending on how close or far away from the intial given value it is, it will do something different to the value using a case structure.(Not positive this is the best way)
Ideally I would like to somehow incorrporate the value that is on the front panel from the user, into the different ranges so they are not set. Is there any way instead of using [ ..10, 11..15, 15.. ] I could use the [..(indicator - 5), (indicator-4)..(indicator +4), (indicator +5)..] as my three different cases? Or is that just crazy and I should be trying to use a different type of structure maybe?
Thanks in advance for the help,
KT

What if you would subtract the reference value before wiring to the case structure?
(assuming you are dealing with integers)
LabVIEW Champion . Do more with less code and in less time .

Similar Messages

Case Structure Based on Changing Input Controls

Hello. I am trying to create a control VI for a quad-copter. Right now I've managed to build a basic program that gets input from some sliders and transforms and sends it to the quad-copter motors through I2C and virtual serial port.
The problem that I'm having is that I want to be able to control the engines either individually or in pairs, so I can achieve motion in all directions. But since I can't have multiple inputs at the same time for each engine, I think I might need a case structure. What I would like to do is have a scenario where depending on whether an input changes and how (either for an individual motor or a group), the case structure switches to that case and takes the inputs specified for that particular case. What I'm thinking is having 10 or so sliders, 1 for each engine, and then 1 each for groups like 1 & 2, 3 & 4 and 1 for all, and depending on whether they change and how, switch to the case where only those particular engines change speed.
Can you please help me out with that? Thank you.

That is one way to accomplish it. I would probably use the event structure. It is not that difficult to use. It is very similar to the case structure.
I would also caution you on comparing two floating point numbers. Due to rounding it is possible that you will subtract two values which are essentially equal but return a non-zero result. You should use the "In Range" VI and set some tolerance value which indicates the numbers are equal.
One last item, do you want your shift registers to be unitialized? If they are unitialized they will retain the values from the last execution of this VI. You may not want that since I assume you would want your motors to be off in the initial state.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

Programmatically change case structure range

I think I already know the answer to this, but I'm going to ask anyway. In the attached image, is it possible to programmatically change the range of numbers the case uses?
Tay
Solved!
Go to Solution.
Attachments:
case structure.png ‏3 KB

To use a property node on a case selector, you need to have a reference to it. There are several ways to open the reference, depending on where the object you want to reference is located.
EASY - If the case selector is not inside another structure and has a unique name, use Open VI Object Reference with the name of the case selector as the input. The owner is the block diagram reference and the object class is a case selector.
FAIRLY EASY - If the case selector is inside another structure or structures and all structures and the case selector have names unique to their diagrams, open the structures from outside to inside as in case 1. After you open the structure reference, get a reference to the appropriate diagram and repeat until you get to the final case selector.
HARDER - Case selector has a unique name, but is buried in a container which does not. Use the Traverse method to find all case selectors, then use the Label property of each to find the right one.
HARDEST - Case selector does not have a unique name. Use the Traverse method to find all case selectors, then find the one you want by the frame labels.
The take-home message from this is that your life is much easier if you give your containers unique names.
This account is no longer active. Contact ShadesOfGray for current posts and information.

Naming the evaluated case statement field with concatenating input variable value

Hi,
I am trying to add the input variable value to case statement evaluated field like below query:
declare @Year varchar(4)
select ProductCode,datepart(mm,Date) MonthValue,
case when datepart(mm,Date) = 1 then sum(Price) else 0 END AS Jan+@Year,
case when datepart(mm,Date) = 2 then sum(Price) else 0 END AS Feb+@Year,
case when datepart(mm,Date) = 3 then sum(Price) else 0 END AS Mar+@Year,
case when datepart(mm,Date) = 4 then sum(Price) else 0 END AS Apr+@Year,
case when datepart(mm,Date) = 5 then sum(Price) else 0 END AS May+@Year,
case when datepart(mm,Date) = 6 then sum(Price) else 0 END AS Jun+@Year,
case when datepart(mm,Date) = 7 then sum(Price) else 0 END AS Jul+@Year,
case when datepart(mm,Date) = 8 then sum(Price) else 0 END AS Aug+@Year,
case when datepart(mm,Date) = 9 then sum(Price) else 0 END AS Sep+@Year,
case when datepart(mm,Date) = 10 then sum(Price) else 0 END AS Oct+@Year,
case when datepart(mm,Date) = 11 then sum(Price) else 0 END AS Nov+@Year,
case when datepart(mm,Date) = 12 then sum(Price) else 0 END AS Dec+@Year
from Sales_Imports where datepart(yyyy,Date) = @Year
group by ProductCode, datepart(mm,Date)
Please help me any other way as this is not working...
Thanks,
Srini

create table Sales_Imports (ProductCode int, Price int, [date] date)
insert into Sales_Imports values
(1,10,'1/1/2014'),(1,109,'2/1/2014'),(1,10,'1/1/2014'),(1,109,'12/1/2014'),
(2,10,'1/1/2014'),(2,109,'2/1/2014'),(2,10,'10/1/2014'),(2,109,'12/1/2014')
declare @Year varchar(4)='2014'
DECLARE @MaxCount INT, @SQL NVARCHAR(max) ,@i INT;
Set @MaxCount = 12
SET @i = 0;
SET @SQL = '';
WHILE @i < @MaxCount
BEGIN
SET @i = @i + 1;
SELECT @SQL = @Sql + ', SUM(CASE WHEN datepart(mm,[Date]) = ' + cast(@i AS NVARCHAR(10)) + ' THEN Price Else 0 END) AS ' +Left(DateName(month,Dateadd(month,@i-1,0)) ,3)+@Year
END
SET @SQL = N' SELECT ProductCode, datepart(mm,Date) MonthValue ' + @SQL
+ N' FROM Sales_Imports
where datepart(yyyy,Date) ='+ @Year + N'group by ProductCode, datepart(mm,Date)
Order by ProductCode, datepart(mm,Date)';
--PRINT @SQL;
execute (@SQL);
--Or your original one
declare @Year varchar(4)
Set @Year ='2014'
declare @SQL Nvarchar(4000)
SET @SQL=
N' select ProductCode,datepart(mm,Date) MonthValue,
case when datepart(mm,Date) = 1 then sum(Price) else 0 END AS [jan' +@year+'],
case when datepart(mm,Date) = 2 then sum(Price) else 0 END AS [feb' +@year+'],
case when datepart(mm,Date) = 3 then sum(Price) else 0 END AS [Mar'+@year+'],
case when datepart(mm,Date) = 4 then sum(Price) else 0 END AS [Apr'+@year+'],
case when datepart(mm,Date) = 5 then sum(Price) else 0 END AS [May'+@year+'],
case when datepart(mm,Date) = 6 then sum(Price) else 0 END AS [june'+@year+'],
case when datepart(mm,Date) = 7 then sum(Price) else 0 END AS [july'+@year+'],
case when datepart(mm,Date) = 8 then sum(Price) else 0 END AS [Aug'+@year+'],
case when datepart(mm,Date) = 9 then sum(Price) else 0 END AS [Sep'+@year+'],
case when datepart(mm,Date) = 10 then sum(Price) else 0 END AS [Oct'+@year+'],
case when datepart(mm,Date) = 11 then sum(Price) else 0 END AS [Nov'+@year+'],
case when datepart(mm,Date) = 12 then sum(Price) else 0 END AS [Dec'+@year+']
from Sales_Imports where datepart(yyyy,Date) = ' + @Year +N' group by ProductCode, datepart(mm,Date)'
--print @Query
Execute (@SQL)
drop table Sales_Imports

How to make Path point from inputed variable

Hi Im wandering how I can replicate the rectangle tool in Illustrator where by I can input sizes into a window and it shall draw an object for me. The problem I have is stating that a point should be a (variable1,variable2) instead of (X,Y)
im using the java ExtendScript Toolkit. so im trying:
var docRef = documents.add();
var piRef = activeDocument.pathItems;
var pathRef = piRef.add();
pathRef.setEntirePath( new Array(
new Array(0, 0),
new Array((shapeWidth), (shapeHeight)) ) ) ;
Although what im looking to do is more complex this is the part giving me trouble
any help would be greatly appreciated

Thank you for the response
Yeah, I understand. I have to put the keyword first, the problem is sometimes I transfer almost around 800 photos at once. I haven't had much time to sort every photos and put the keyword on every Path photo. Beside so many photos in my library, and not well-organized. Also I have tried any possibilities of relevant criteria in smart album. But still zero result.
So, before I actually take the time to organize my thousands of photos manually, I was thinking maybe there's another way, simple and smart one, with this smart album feature. Anyone?
Ismail

Pass the value of the current case in a case structure to a global variable for use in VIs.

I have built a large queued state machine (>100 cases). In each state, I run a VI that I have created. These VIs are usually not very different from one another. In many cases, I could simply use the same VI over and over again. There is only one problem with that. None of these VIs know which case to send the program to next. I have to change the value of the "NEXT_CASE" constants in the VI and save it under a new name to be inserted into each new case. Now my program consists of hundreds of VIs whose only difference is the value of their "NEXT_CASE" constants. This causes all kind of headaches when I have to insert new cases into the state machine, and it is just too much for me to deal with.
I need to be able to use a global variable to keep track of the current case within my VIs. I could change it from a string to a number and add or subtract from it to determine which case the program should go to next. Since I'm usually only skipping from one case to the next (or the previous) I could use the exact same VI in most cases. Can anyone tell me how to create a global variable that contains the value of the case in my case structure that I could use within my VIs to keep track of the current case? Let me know if you have any questions.

Instead of defining the next state inside the subvi, why not do it in the main vi inside each state case? An output from the subvi could be used with a case structure to determine the next state. Sort of like, if the subvi returns 0 then next state is State3, else if the subvi returns 1 then next state is State4.
Message Edited by tbob on 08-19-2005 03:15 PM
- tbob
Inventor of the WORM Global
Attachments:
NextState.PNG ‏5 KB

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

Can a case structure execute multiple cases?

So I have a VI set up with a mutiple option case structure to select which input a voltage is read from (there are 32 options). Now that I have it made, I realize that sometimes I may want to read from multiple inputs at once.. Is there an easy way to change my setup so that it executes multiple cases at a time? Right now my control is a slider to choose the case. What would be a good front panel control choice to be able to select multiple options? Thanks
Solved!
Go to Solution.

You can build an array of your options and loop through the required cases. As mentioned, a case can only perform 1 case per loop.
A good front panel control would be a cluster or an array of booleans (e.g. a tick box per option), easy to loop through.
/Y
LabVIEW 8.2 - 2014
"Only dead fish swim downstream" - "My life for Kudos!" - "Dumb people repeat old mistakes - smart ones create new ones."
G# - Free award winning reference based OOP for LV

Using local variables with a case structure

I recently decided that I didn't want to nest a bunch of case structures for a program I am creating. I have two variables, N1 and N2, and I want to say execute Case 1 if the integer input to the terminal is less than N2. Case 2 if the integer input into the terminal is greater than N2 but less than N2+N1. Case 3, integer greater than N2 + N1, but less than N2+N1+N2. Case 4, you guessed it, Greater than N2+N1+N2, but less than N2+N1+N2+N1. When I try to type the variable name into the bar and use the ... like you do with integers it changes the variable name to a string.
Am I just thinking of this the wrong way? I have a sensor setup in a square and I am using a matrix card hooked up to the sensor bundle to send signals from each sensor to each other sensor, but not for those along the same sides.
Tom

I see the nested case structures which is what I didn't want to do, but I will have to because I am tired of looking at this. Thank you for the help on this. I appreciate it.
The sensor network is shown in the image included. Lets say we number the sensors in a clockwise direction starting on the lower left hand corner. Each element needs to both send and recieve data to all other elements except for the one in the row it is in. So sensor 1 would sent to sensor to sensors 5 - 18. Then sensor 2 would send to 5 - 18. Sensor 5 would sent to 1 - 4 and 10 - 18. Etc.
Lets say if this were a circular array it would be easy. Two nested while loops. And the only condition I need to worry about is that sensor N is not both sending and recieving at the same time. Each while loop, or for loop - doesn't matter, will start at 0 and go to N-1. Each i and j will have +1 added to them, and as long as they are not equal preform the data operation.
Just some fun logic to think about
Tom
Attachments:
rectangular.jpg ‏12 KB

How can I have multiple inputs into the selector terminal of a case structure

Hi everyone
I have a question on how to wire multiple inputs in to the selector terminal of a case structure.
Currently, I have three switches, each switch determines different case. So if I switch the switch 1 is on, the numeric indicator will show 1. If the switch 2 is on, the numeric indicator will show 2, so on and so forth. However, the selector terminal will not allow me to wire multiply inputs into the case structure, I tried Bundle by Name, Bundle and Array to Cluster, but they did not work. I set the case structure with 3 cases, they are 1, 2 and 3.
Could someone help me please. I have attach an image and the VI of the work I did so far.
I have another question, is there a function which can toggle other switches to off when there is a switch has been toggled on.
Thank you very much
Tommy
Attachments:
Trial - Case Structure.vi ‏7 KB

Tommy, attached find a cheeseball way of doing this that has given me a LOT of mileage over the years. IT lends itself nicely to a couple of really good practices that NI recommend, but I have given you the bare-bones to "see under the hood".
The recommended practices:
1. You can make this a nice tight sub-vi where you can put it into a core library of routines that you'll use over the years, even extending the logic to look only for changes, etc.
2. If you are thinking about Front Panel design considerations, you'll want to use arrays of controls where possible, as that's a nice neat way of containerizing your switch for both the FP and Block Diagram.
Have fun. I have TONS of these types of things, so feel free to PM me if you have any other needs.
Wes
Wes Ramm, Cyth UK
CLD, CPLI
Attachments:
Boolean Switch Logic.vi ‏11 KB

How do i output multiple arrays from a case structure to create one larger array

I currently have a vi that has one hardware input that i needed to take a measurement then be moved and take a similar measurement at a different point. To accomplish this i used a while loop inside a case structure. The while loop takes the measurement and finds the numbers i need while the case structure is changed per the new measurement location. I want to take the data points i have created in each case and output them into a single table. I assumed to do this the best way would be to get the data from each case into its own built array and build a larger array but I cant get the information out of the case structure so that it all inputs at different places.
thanks for your help
Attachments:
Array.vi ‏30 KB

Hi Ross,
attached you will find a solution for your table building problem.
I would suggest thinking about program design - having the same case content in several cases doesn't make sense. I also would not want my user to press several stop buttons depending on choosen measurement...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome
Attachments:
Array.vi ‏45 KB

In the attached VI I dont understand why data from the inner case structures are not being transmitted to the array.

In the attached VI I don't understand why data from the inner case structures are not being transmitted to the array.
Thank you.
Solved!
Go to Solution.
Attachments:
TEMP.vi ‏25 KB

It took me some time to figure what you are trying to do but I think I have it now.
The SR is still required.
What is happening is your "Bundle By Name" is replacing all of the fields of the cluster, not just the value coming out of the case structure. So to maintain the cluster stuff you do in earlier iterations you can either...
1) Put the "Index array, Bundle by name, and Replace array" inside the case structure and ONLY bundle the value you are setting in that iteration. (as you will see Tim post shortly)
OR
2) Move the Index array before the Case, unbundle all of the fields and feed teh case structure and run them across the case so that ALL of your output tunnels come from the coresponding input tunnel EXCEPT for the filed you are trying to set.
Ben
Message Edited by Ben on 05-05-2010 01:31 PM
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Range setting in case structure

Hello everyone! I'm working on an engineering project where I read in a sound input and if it's on high volume, a red led connected to a MyDaq box lights up, if it's on low, the green LED lights up, and both will be off if there's no sound input. I posted a screenshot of how my vi currently looks. The problem I'm having is, I want to set the range that will be considered as the low volume, and a range considered as the high volume on my case structures. I'm not sure exactly how to do that. I currently have an "In range" function there where I set the max and min values. THe problem with this is, it outputs a dynamic data that I cannot connect to the appended array. Any help would be great. Thanks!
Attachments:
projecttest2.vi ‏91 KB

Thanks for your response. I'm new to labview (which isn't really an excuse) and we just went through the real basic stuff for this course. That's why my code just looks like a mess. I'm just trying to use the case selector because I thought it'd be more efficient, since, if I think of it in written code, they're kind of like if-else statements, right? I thought I needed to multiply by a thousand because I am measuring the amplitude of sound input. Whenever I test it out, the numbers are really small. I just figured it'd be easier to multiply it by a thousand and set the range with bigger numbers. I'm also trying to get an LED to light up on a range of volume. That's why I need two comparisons. Like, if the volume is between the range of 2000 to 3000, the green LED lights up, and if it's between 1000 to 2000, then the red LED lights up. If the signal is equal to zero, then no light turns on. Anyway, I scrapped the whole idea of using case selectors because I don't have time to learn my way through it and finish on time. I attached a new version of my VI. It's a more simplified version. I don't know how to connect the LED boolean indicators into my array and into the DAQ Assistant (it's not on the vi yet but I do need one so the program knows to read the output into the LED's on my myDaq box. Sorry for the trouble! Thanks for any advice you can give.
Attachments:
projecttest1.vi ‏55 KB

Changing an output box in a case structure to an input box

Hi, I have been struggling with the following problem in Labview:
Hi, I was working on a wiring diagram in Labview and I was trying to
wire an absolute value symbol to the right border of a case structure.
The problem is that I get an output box (an white filled box with an
orange border) instead of an input box (an orange filled box). How
would I change the output box into an input box? I have tried Ray
Kong's method, which is to add a constant and that would make the box
solid. It worked only once but when I tried it on another output box
it did not work. Any suggestions would be appreciated. Please
include step by step instructions as I am still learning Labview.
Thank you
Muhammad Asfour

The box type will be appropriate for what you have wired to the box.
When you say you want an "input box", do you REALLY want an input box (ie, a
connection bringing a value from outside of your case statement to the
inside of your case statement) or do you mean that you want your output box
(a connection bringing data from inside your case statement to the outside)
to be solid orange? The output box will go solid orange when you have a
connection from EACH case to the box. Remember that a single output box
(usually on the right side of the case statement) must be connected to
something in each case of your case statement. It will be filled white
until all cases are wired.
Write back if this isn't clear of if I have mis-understood your situation.
Hope this hel
ps.
Jim
"Muhammad Asfour" wrote in message
news:[email protected]..
> Hi, I have been struggling with the following problem in Labview:
>
>
> Hi, I was working on a wiring diagram in Labview and I was trying to
> wire an absolute value symbol to the right border of a case structure.
> The problem is that I get an output box (an white filled box with an
> orange border) instead of an input box (an orange filled box). How
> would I change the output box into an input box? I have tried Ray
> Kong's method, which is to add a constant and that would make the box
> solid. It worked only once but when I tried it on another output box
> it did not work. Any suggestions would be appreciated. Please
> include step by step instructions as I am still learning Labview.
>
> Thank you
>
> Muhammad Asfour

Case structure back and forth from LED

Hello, I'm trying to make a case structure switch back and forth everytime a boolean LED indicator goes off. I want case one to start when a button is pushed, switch to case two when an LED indicator goes on, then switch back to case one when that same LED goes on again, then case two the next time the light goes on, and so on. The LED is set to go on every ten seconds. So far i have the case structure in a while loop but im not sure how to get them to switch back and forth using this one LED. Any suggestions?

Then you have two asynchronous parallel loops, and you want one of them to receive information (Boolean) from the other in order to determine its state.
If the loop with the elapsed time contains nothing but elapsed time, then consider moving it to the first loop.
Otherwise, you should use a form of synchronization communication, such as a Notifier or User Event, to send data from your loop with the elapsed time to your loop with the case structure.

Case Structure Ranges Determined From Input Variables

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