State machine with using event case

Hallo everyone,
i have a question about how to realize the "Timeout". In the flow diagram below we can see 2 different situation:
1. in the 1st Situation i have used the state machine, it begins at state 1, which contains a event case. In there it will be at first determined, if the input value has changed within 10 second, if it didn't, the state machine will go to state 2, if it 's changed, will be furthermore determined, whether the input value equal to 3, if yes, the state mashine will jump to state 3, if no, jump back to state 1. (this VI i have done before, you can take a look at the Attachment).
2. my question is in the 2nd situation. It begins also at state 1. In there the input value can also be changed (once or many times) or not. If the value has not been changed within 10 s, or even though it's been changed many times within 10s, but it's never been equal to 3, the state machine will go to state 2; only when the input value within 10s equal to 3, it can jump to state 3.
This problem i have no idea how to solve, does anybody have idea or better methods?
thanks a lot!!
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Attachments:
situation 1.vi ‏12 KB

The statement in the OP is not covering all cases.
mexaviesta wrote:
2. my question is in the 2nd situation. It begins also at state 1. In there the input value can also be changed (once or many times) or not. If the value has not been changed within 10 s, or even though it's been changed many times within 10s, but it's never been equal to 3, the state machine will go to state 2; only when the input value within 10s equal to 3, it can jump to state 3.
This problem i have no idea how to solve, does anybody have idea or better methods?
thanks a lot!!
Just check my implementation for Situation 2 and let us know, if it works for you.
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Attachments:
Situation 2.llb ‏40 KB

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Problems closing several loops in a state machine with an event structure

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example.png ‏108 KB

You have a classic race condition due to overuse of local variables. If the stop event fires in the upper loop, the local variable connected to the loop termination condition has already been read (it is false!). This means that the upper loop will iterate once more and again wait at the event structure for the next event. At this time, the local variable connected to the loop termination is TRUE, but the loop cannot complete until the event fires again, for example if you press the stop button once more.
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I am trying to find the best way to shutdown a program that consists of a queued event state machine architecture with multiple parallel loops. Can anyone recommend the best way to accomplish this in my attached VI? (From browsing the forum, this seems to be a common question but I haven't found a solution that works for me.)
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Thank you!
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Attachments:
Queued event state machine parallel loops empty.vi ‏46 KB

Thanks for clarifying that, Ravens Fan.
I marked crossrulz as the solution for pointing out User Events to me.
I also adopted Ravens Fan's suggestion to keep the Shutdown procedure out of the Error Handling Loop. This has simplified the architecture by eliminating the need for Notifiers. Instead, I have used booleans in case structures to stop the Event Loop and State Machine, and Release Queue to stop the Error Handling Loop.
For reference, I'm attaching my corrected code.
Thank you to everyone who helped!
Attachments:
Queued event state machine parallel loops empty in progress.vi ‏44 KB

An example of a state machine with transition array?

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Need help created state machine with timed digital output

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Attachments:
State Machine Digital Output.vi ‏28 KB

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Adnan Zafar
Certified LabVIEW Architect
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Steve Chandler wrote:
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In this SM
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How can A state machine be used to monitor flow from a micro motion using bridgeview/labview

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How to do state machine using events .

Hi all.
i like to create a state machine using events methos .
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JGar wrote:
Wouldn't it make sense to have the entire state machine within one event case? When you trigger the event case the state machine then executes like a normal state machine.
DO NOT DO THAT!!!!!! Long parts of code do NOT belong inside of an event case.
The Event Structure should be in its own state and the state machine should to to that state every once in awhile to check for user events.
Alternatively, you could put just the state case structure inside of the Timeout event case. Something like this: http://www.notatamelion.com/2015/03/02/building-a-proper-labview-state-machine-design-pattern-pt-2/
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Wiring Data in a State Machine

I have a state machine with about 20 cases all handling different user interactions and all completely independent of one another. That is, what one case does has nothing to do with what another does (for most of them anyway). They just execute one case and then go back to the default case. Some of them though do require data to be passed out of one case so that it can be read in another (actually not the data but just the data structure to be reused). Shift registeres work just fine of course, but this requires me to wire this data through all the other cases that don't need it just so they can have an output for the tunnel. Is there anything else I can do to avoid wiring paths through every case that doesn't actually need the data?

Here's a real simple example. I can't give you too much insight with respect to the memory usage, except to say that I've never had any problems doing things this way. I've written a couple of big vi's with 30 - 40 variables clustered this way.
Attachments:
Clustered_Variables.vi ‏35 KB

How to use a event structure with a state machine

First, I would like to inform you that I only work on LabView part time, and have much to learn. Anything I do learn, I usually forget until I need it again, because I only work on it part time.
Using your StopWhileLoopMOD[1].vi, I am trying to put a state machine inside the event structure.
Related link: http://forums.ni.com/t5/LabVIEW/How-to-stop-while-loop-in-Event-case/td-p/465564/page/2
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Is there a good example of an event structure?
metzler CLAD
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I'm not sure exactly what you are asking, but it sounds like you want to script a bunch of tests and if the user says stop, to immediately stop the current test and abandon the others? I'm going to assume that you know how to clear the array so that it will abandon the others, so I'm guessing that you are having trouble abandoning the current test? If this is indeed the case, then the problem is that you are not able to propagate the message from the main VI FP which is the GUI to the sub vi which is the test, where the test may or may not have a GUI (FP visible) of it's own. Threading was the first thing to come to mind, but this may not be necessary using events.
You can do this by passing a refnum of the stop button to the subVI, where you can then add that wait to the event case structure.
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Hope this helps.
A
Attachments:
mainvi.vi ‏17 KB
subvi.vi ‏33 KB

How to use elapsed time function with state machine in Lab VIEW

Hello
I've been trying to use state machine with elapsed time function in order to sequentially start and stop my code. The arrangement is to start the code for 1 minute then stop for 5 minutes. I've attached the code, the problem is when I place the elapsed time function out of the while loop it doesn't work, on the other hand when I place it inside the loop it does work but it doesn't give the true signal to move to the next state.
Could you please have a look to my code and help me to solve this issue.
Regards
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Solved!
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Attachments:
daq assistance thermocouple(sate machine raj).vi ‏436 KB

Rajab84 wrote:
Thanks apok for your help
even with pressing start it keeps running on wait case
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Best Regards
Rajab
OK..I modded the example to stop after 2 cycles. Also recommend taking the free online LabVIEW tutorials.
run vi. case statement goes to "initialize", shift registers are initialized to their constants. goto "wait"
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Once cycle count reaches 2, stop while loop....
Attachments:
Untitled%202[1].vi ‏42 KB

Producer Consumer with a state machine within the consumer

Hi All,
I have been trying to develop a data acquisition system with the producer consumer architecture. To the left of the two main loops I initialize the serial port and any constants and variables im using. I also have an obtain queue VI needed for enqueue and dequeue. Then in the producer loop i have a state machine. The first state is where I wait for a button press on the front panel to write a GO signal on the serial line which will tell the device connected to the serial port to begin sampling data. After this button press I go into the next state which is called my read state.
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4 packet type 2 parsing - "" ""
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A couple of things more to go along with Ben's pointers:
You convert your data from a string, to a U8 array, to a Hex string array in the producer loop, then convert back to a integer to determine what to do with it. In the process, you create two or three copies of your data, slowing yourself down quite a bit. The code would be quite a bit more efficient if you left the data as a U8 array. You can change the format of the controls and indicators to show hex values instead of integer by right clicking on them and selecting Format and Precision...
Your search code is fairly inefficient. I made a whack at making it a bit better. See attachment below.
If you continue to run into race conditions, you can debug them using a calls to the Windows debug write sprinkled liberally about your code. Check out the post here for more information.
Don't let your lack of format LabVIEW training stop you. The biggest thing to get is the data flow paradigm (aka data is wires, not registers). Once you get past that and learn how to pass data around using shift registers, queues, events, etc, you are most of the way to mastering LabVIEW. The rest is just learning the plethora of functionality LabVIEW gives you (yes, I have reimplemented LabVIEW native code more than once in the process of learning).
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This account is no longer active. Contact ShadesOfGray for current posts and information.
Attachments:
serialUtil_V3_DFG.zip ‏137 KB

Event structure in a State machine

Hello all,
I've got a state machine with a sort of Stand-by state from where a user can select the next state using buttons. I tried using an Event structure with value change to select the next case but when the state machine is in a specific case and the button of an other state is pressed the whole thing blocks. I've attached an example, the LEDs just indicate what state you are in.
Thx for your time,
Bert
edit: Indeed, I miss-clicked
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Attachments:
Question.lvproj ‏2 KB
Question.vi ‏21 KB

All your inner while loop should not be there, they just gum up the gears. It is a bad idea to trap the code inside inner loops, because during that time, events cannot be handled, whil they are still queued up. For example if you are in state 1 and press state 3 100 times, then exit state 1, state 3 will be entered 100 times in a row, witout a possibility of escaping.
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Here's is a quick draft showing the same code without inner loops and without the event structure just to give you an idea what I meant. See if it gets you some ideas. It is still not perfect ...
(Sorry, I had to disconnect the type definitions, because you did not include it)
LabVIEW Champion . Do more with less code and in less time .
Attachments:
Question 1mod2.vi ‏19 KB

Can I have multiple event structures with the same event cases?

Hello,
I'm doing an application that reproduces the front panel of the HP6675A power supply. To achieve this, I have done a state machine with different states
(initialize, measures, voltage, current, ocp, ov, store, recall, etc). In each state, should have an event structure that catches the events of the buttons, like for example: if the current state is the Voltage mode and the user press the current button the next state will be the Current mode. For this in each state of the state machine should be the same event structure with the same events.
My problem is that the Vi doesn't work properly when I have multiple event structures with the same event cases. There are some possibily to do this, and how? Or is impossible to have multiple events? I have been reading some posts, but I don't find solutions.
Any help is appreciated.
Thank you very much.
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natasftw wrote:
Or as others mentioned, make two parallel loops. In one loop, have your state machine. In the other, have just the Event Handler. Pass the events from the handler to the state machine by way of queues.
A proper state machine will not need the second loop. The "Wait For Event" or "Idle" state (whatever you want to call it) is all you really need in order to catch the user button presses. The setup is almost there. Maybe add a shift register to keep track of which state to go to in the case of a timeout on the Event Structure.
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State machine with using event case

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