WORM Global

Continued from old thread.
Here is my latest version of the WORM Global. For those who are not familiar with this project, a WORM Global is a way to store variables where you can write to them once. WORM stands for Write Once Read Many. This vi holds an array of variants.
You can add any variable at any time. When adding, you write the value to the variable. After adding, you cannot write to it again, there is no mechanism to do so. But you can read the variable as many times as you wish. This prevents race conditions from happening.
It is useful to store constants (variables that are defined and then don't change). An example of its use would be to store GPIB addresses of instruments, datalog file names, config file names, constants flags, and others.
Upon first call, the array of variants is emptied to get rid of leftovers from previous use. It is best to call this vi inside a loop, with two arrays as inputs to the loop: an array of global names and an array of corresponding values. Wire in the Add enum to the Action input. Now the globals are set and can be used anywhere in the program. To use, call the vi again with Read as the action. Wire in the name of the global you want to read. The output is a variant, but can be converted to its proper type using Variant to Data function.
Another action is to Delete. You can delete globals that are no longer needed at any time.
If trying to add a global with a blank name, you will get an error. If trying to read a global with a blank name, you will get an error. If trying to add a global whose name already exists, you will get an error. If trying to read a global whose name does not exist, you will get an error. If you try to delete a global that does not exist, or one in which the name is blank, you will get an error.
Please review the vi and give me some feedback. If you see problems, bugs, or have a better idead, I would love to hear about them.
- tbob
Inventor of the WORM Global
Solved!
Go to Solution.
Attachments:
WORM_Globals.vi ‏40 KB

One question, any specific reason to use an array of clusters over a Variant with attributes?
The searching for a specific tag (or name) should be way faster (something with black and red books) in large datasets for a Variant attribute list vs. an Array of strings.
Why not skip the search when the Global name in is empty?
You picked an error number from the NI error-list that is not standard and is not available to users.
This is really nit-picking but you used a 'default' state in an enum-based case structure
Why expose the worm globals to the outside world?
here's a Variant based on your code.
Ton
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Attachments:
WORM_Globals_Variant.vi ‏37 KB

Similar Messages

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.
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Message Edited by tbob on 08-19-2005 03:15 PM
- tbob
Inventor of the WORM Global
Attachments:
NextState.PNG ‏5 KB

How do I open and close VIs from within a VI?

Ladies and gentlemen,
I would like to use a VI to open and close other VIs based on user input. Example: The first VI will have text that reads: "Does the car have heated mirrors?" There will be two buttons: one for "YES" and the other for "NO."
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Instead of opening and closing vi's, just create one main vi with a state machine architecture. Search for examples on state machines to get a basic understanding of them. This is pretty complex so I have written an example of how this could be accomplished. The trick part was the 2 minute timer (my vi is set for 5 seconds for quick testing). Each state produces a question, and depending on the answer, the next state is inserted into a queue. You can add more states for more questions and answers. Notice that the boolean buttons can be hidden if you just want to show one button (like Next) instead of two buttons (Yes and No). Study the vi and let me know if you have questions.
- tbob
Inventor of the WORM Global
Attachments:
Q&A.vi ‏166 KB

Front panel of SubVI locks on 2nd call

HI!
I'm calling a SubVI and pass a Boolean Reference to this SubVI. In the SubVI I'm executing a While loop. The stop condition is the value of the boolean control in the VI that calls the SubVI. (Boolean Refnum + Property Node: VALUE connected to while stop condition)
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ANDY

I tried what you described, using LV 7.1, and I have no problems running the vi over and over again. See the attached examples. Ref1.vi calls Ref2.vi and passes the Boolean reference to it.
- tbob
Inventor of the WORM Global
Attachments:
Ref.zip ‏21 KB

How do i sweep two voltage at the same time by using for loop ?

Hello, Can anyone help me on this topic ?
My problem is to sweep Vds and Vgs as same time vs Id in MOSFET by using for loop. I also use the Agilent power supply source. Let me tell a litle bit about what i'm doing. For different value of Vds, i will get Vgs vs Id curve. (The x axis is Vgs, the y-axis is Id).
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It is easier to use a while loop. Dennis beat me to the punch. Here is my solution:
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Message Edited by tbob on 10-17-2005 01:00 PM
- tbob
Inventor of the WORM Global
Attachments:
RampVoltage.PNG ‏8 KB

Listbox one line at a time

I want to add one line at a time in listbox/textbox just like InsertTextboxLine funtion in CVI. I can not find similar VI in labview. I think I can do it long way...by saving listbox to an array then append my line at the end of the array and send updated array to listbox..these are lot of steps to add one line to listbox/textbox...
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CVI 2010
LabVIEW 2011 SP1
Vision Builder AI 2011 SP1

Actually, the way to append an item to a list box is to create an Item Names property node for the list box. Then you can use Insert Into Array, and write to another property node for Item Names.
Message Edited by tbob on 10-03-2005 02:31 PM
- tbob
Inventor of the WORM Global
Attachments:
ListBox.PNG ‏3 KB

How do I select a control based on another control's selection and how do I remove enumerations from a control?

Hi everyone,
I have a question and I *think* the answer may be the new active controls, so here goes: I have a control which contains a variety of enumerated items - essentially a typedef enum. I may have up to several dozen items in this control, like this:
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Thanks,
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Unfortunately, you cannot edit the list of enums during runtime, only during edit mode. You can use a ring control however. Then you can use the Strings[] property to set the selections to whatever you want depending upon the 1st enum. See attached vi.
- tbob
Inventor of the WORM Global
Attachments:
ChangeRing.vi ‏52 KB

Trigger two FPGA instances at same time

I have some basic FPGA code that transmits data bits over a serial bus (RS485), The code is written so that it waits in the first state of a state machine in a single cycle timed loop. Upon a certain trigger, it starts reading a FIFO containing data and sends the data out on a Tx line. It does this until all bits are send then it goes back to the first state to wait for the next trigger. The trigger is needed because windows has to fill the FIFO first before the FPGA can start sending.
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I had to do it this way because sometimes I want to transmit on both busses, and sometimes just one or the other. Numeric values are used to determine which to transmit on. Now the transmissions start at almost exactly the same time, 1 or 2 nanoseconds apart. But the trigger process seems very far fetched to me. I was wondering if there is a better solution. I'm pretty new to FPGA.
- tbob
Inventor of the WORM Global
Solved!
Go to Solution.

tbob wrote:
Basically I did the same thing using FPGA Memory. From windows I write to a numeric control which resides inside the FPGA Main vi. In the FGPA main, I write to the Memory. Inside the FPGA subvi, I read the memory and decode the value to either use one or the other or both busses. After fooling with this for some time, because the Read Memeory needs to use a shift register (probably due to it taking an entier clock cycle), I got it to work. Both busses trigger at the same time. I guess it really doesn't matter if I use a FIFO or if I use Memory. The main issue is that I have to write from Windows to the FPGA Main, and then from the FPGA Main to the FPGA subvi. Then the timing is exact as far as the subvi is concerned.
There are a couple of advantages to using two FIFOs over your approach. First, you don't need the shift register for the memory location. Second, you don't have to worry about which VI is responsible for clearing the memory location, nor do you run the risk that one of your subVIs will execute twice, or not at all, if the memory isn't cleared at the right time. Perhaps most importantly, you'll save yourself space on the FPGA because you won't need arbitration - the extra code that gets added when two parts of the FPGA try to access the same resource at the same time. In your case, both instances of the subVI access the memory block concurrently, so the FPGA compiler adds extra logic to prevent conflicts. If you only read the memory block in one place and only write it in one place (the read and write can be in different loops or subVIs) there's no need for arbitration. By using two FIFOs you can keep them independent and avoid the conflict resolution code. See the help for "arbitration" for more details.

Convert timestamp to string with milliseconds showing.

I have two questions. The first is I need to know how to convert the timestamp that displays from "Get Date/Time in seconds" to a string format. I found the vi that converts to string but it stops at seconds and cuts off the milliseconds. I wired true to the "Get seconds" terminal so I get the time in seconds, I just don't get the millisecond value. Also I need to know if the clock from "Get Date/Time in seconds", is synchronized (or shows the same time down to the millisecond) with the timestamp that shows in the CAN read vi. I need to have the clock/timestamp from the CAN read synchronized with the "Get Date/Time in seconds" clock/timestamp. I am trying to compare delays in the CAN so I need precision down to the millisecond.

Use Format Date/Time String. For the format code use %H%M%S%4u to get two digits for hours, two digits for minutes, two digits for seconds, then a decimal, and after the decimal you get 4 digits for fractions of a second. Replace the 4 with a 3 to get milliseconds, or with a 1 to get tenths of a second. You get the idea... See attached vi.
- tbob
Inventor of the WORM Global
Attachments:
Milliseconds.vi ‏12 KB

Terminating Event Generate an Error

Hi All.
My custom workflow has asynchronous task where the terminating events trigger from ABAP program and passed some data.
This task will completed upon custom event "ACCEPTED" raised in the system based on certain keyfield and continue next steps.
Terminating events tab contains element WIOBJECT_ID and my custom event "ACCEPTED".
Binding is use standard element Binding details as per standards, &_EVT_CREATOR& --> &INITIATOR and &_EVT_OBJECT& --> &_WI_OBJECT_ID&
I though this is the only step that I need to do and of course wait step.
However when I test this terminating event via SWUE with proper object key, event trace transaction reported event "ACCEPTED" for task TS95000052 not defined as start/end event.
I check in instance linkage transaction, linkage is activated for my object type, "ACCEPTED" and receiver type "WORK ITEM".
Event type linkages between event and my asynchronous task also active.
Will someone give me a clue, what should I do to resolve this issue?
Many Thanks

You cannot exit from a for loop until it is done. Use a while loop instead. Also, using the event structure in this case causes all kinds of exit problems. Try it and you will see what I mean. Instead, use the abort button itself. Put a case statement at the end to give the error output if the abort button was pressed. See attached vi.
- tbob
Inventor of the WORM Global
Attachments:
abortTesting.vi ‏45 KB

Probleme for writting in to the file

Hello, I have a problem in my applicaion and I need your help.
My problem is the following:
I have a vi Entrées Consignes1.vi, when I run this vi, It open the file for exemple : FAUX.txt (which contain the expression like name = value),after the opening, the differents values display in my Entrées Consignes1.vi. up until then , that's ok!!
But my problem is when I modify some values in my panel control and when I click to the button" Modifier Données" I' d like save it in the same file without affect the different name.I'd like just modify the values because in my solution,I don't know what make?
I send you the Entrées Consignes1.vi with the file FAUX.txt
Thanks you very much for your help.
My seconds question is what exactly is the difference of Labview and Labview Real time?
Attachments:
Dossier.zip ‏31 KB

Pardon, j'ai oblier l'attachment.
- tbob
Inventor of the WORM Global
Attachments:
EntrÃ©es Consignes1.vi ‏101 KB

How do you save characters in an array and then output the characters as a string one by one.

I want to know how to save a number of different characters to an array. then after open this array and read these values one by one as a string.

Input to your loop has indexing enabled. What happens is that on the first iteration, the indicator displays the first string in the array, then in the next iteration, the indicator displays the second string in the array, the first one is overwritten. This happens so fast that all you see is the second one. Look at attached vi in LV6.1 to see how to concatenate both into one indicator. You really need to study Labview to learn the functions. Go to NI's website and search for Labview tutorials.
- tbob
Inventor of the WORM Global
Attachments:
ConcatString.vi ‏28 KB

How could I choose some bytes from HEX string and then convert it to a decimal value?

Hi I am working with an OMRON E5EN temperature controller using VISA serial to get data, I send the Read from Variable Area command and get this string in hexa 0230 3130 3030 3030 3130 3130 3030 3030 3030 3030 3041 3203 71 or .01000001010000000000A2.q in ASCII this string means:
02 STX
3031 3030 Node and subadress
3030 End Code Normal Completion
3031 3031 Command Read from Variable Area
3030 3030 respt code Normal completion
3030 3030 3030 4132 Hexadecimal A2 = 162 (this is the temperature data that I want to show in decimal)
03 ETX
71 Block Check Character
I want to choose the eight bytes for the temperature data and convert it to a decimal number. I have seen the examples to convert a Hexa string to decimal but I do not know how to choose the specifics bytes that I need.
I have look for a driver but i didn´t find any. I am a beginner so please include especific topics for me to study in your answer.
Thanks
Carlos Fuentes Silva Queretaro Mexico

If the response always has the temperature starting with byte 15 and is always 8 bytes in length, you can use the String Subset function to get those bytes out of the string. Then use Hex String to Number to convert to a decimal number.
Well someone already beat me to the solution:
Message Edited by tbob on 01-04-2008 04:42 PM
- tbob
Inventor of the WORM Global
Attachments:
HexStr2Decimal.png ‏7 KB

Releasing Queue in Producer Consumer model

I am having a VI which reads data from ethernet,writes to disk,processes and displays. Since lot of processing and displays are there, I am converting it to a Producer- Consumer model so that no data is lost.
I am using 2 loops. IN the Producer I am doing the UDP read and Write to disk functions.and use the enqueing also.In the Consumer loop I am dequeing it and do all the processing and displays.My idea is to avoid any data loss in UDP reception and file writing.
My confusion- where to use the release queue?from the Producer or Consumer ? In a third loop ? Should it be in a sequence structure ?
How to set the loops stop conditions ?
My requirements for stopping - when I press the stop button the program should stop completely(the Consumer loop should stop only after dequeing and processing all the data in the queue). If i don't press the stop button the whole program should run continuously (if data does not arrive for some time it should wait without time out-i am using -1 for the time out condition in UDP read.)

Here is the ultimate Producer-Consumer loop. It queues a stop command when the stop button is pressed. This ensures that every element is dequeued and processed before the bottom loop stops. The last queue data to get processed is the stop command because after you press the stop button, the top loop stops enqueueing more elements.
If your data type is other than a string, you can create something to represent stop, like NaN for a numeric.
Notice the shift registers. This is good practice. Every loop starts with an error out of the previous loop. If an error occurs, it is passed on to the next loop iteration. Also, if an error occurs in the consumer loop, the loop stops. It is good practice to put shift registers on the queue reference also, but not necessary in this case. If you use a For loop, and the loop iterates 0 times, the output of the queue reference would be a null reference, and the Release Queue would not release the queue. With While loops, they always iterate at least once, so it isn't necessary. Its just good practice to make a habit of using shift registers so you don't forget when using For loops.
Notice also that the error in to the Release Queue is not wired. If there were an error, the Release would not take place. All errors are merged at the end to report exactly where an error occured. A timeout is included in case an error prevents the stop command from being enqueued or dequeued.
- tbob
Inventor of the WORM Global
Attachments:
ProducerConsumer.vi ‏53 KB

Date and time stamp in array

Hello,
I am using Labview 8.0 and I would like to include a date and time stamp each time data is collected and include this as a 5th column in the final array. I inserted a random number generator instead of devices so it would be easier to understand and test. I am new to Labview and have never created a date/time stamp before. Any help or advice would be appreciated.
Dave
Solved!
Go to Solution.
Attachments:
Timestamp.vi ‏16 KB

Yes you need to convert all to strings since the timestamp in HH:MMS is a string. In the string palette, there is a sub-palette full of numeric to string conversion tools. Use the Number to Fractional String to convert all numerical data to strings. Use the Format/Date Time String function (found in Timing palette) to convert the timestamp to HH:MMS. See the format string in my example.
- tbob
Inventor of the WORM Global
Attachments:
TimestampAssistance[1].vi ‏14 KB

WORM Global

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