Multiple same states in a state machine

Hi all,
This is a follow up on a post at the wrong location. I have attached one state in my state machine. That state appears maybe 3 more times in the state machine, so maybe I should make it into a subvi instead, but I was thinking since there are not too many low level nodes and leaving the code in that state out of a subvi seems to be more clear, I thought maybe leaving the code out is better. Not sure which way to go, please feel free to give me suggestion.
Yik
Kudos and Accepted as Solution are welcome!
Attachments:
ALRM_AlarmSummary_BD.png ‏19 KB

If the state is the exactly the same I would not recommend copying it. If you need to make a change to the code you now have multiple places to make the update. Also, rather than making it clearer what is happening I think it leads to more confusion since someone looking at the code will spend time trying to figure out why there are multiple instances of the same state. If you want to document the flow (actually the state transitions) then simply document them and keep that document up to date. That documentation would most likely be easier to read and see what the system is doing then reverse engineering the code.
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

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Trying to create multiple state machines out of same VI to monitor each cFP channel results in what seems to be shared memory between machines

Hi,
I'm trying to create a state machine which monitors a single channel on a field point. I want to monitor up to 64 channels at a time, each one with different instances of the same VI. The VI itself needs to maintain information mainly through feedback nodes both in its own block diagram and subVIs within.
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My attempted solution to all of this was to make the Channel Monitoring VI along with all SubVIs reentrant and "pre-allocate" for each instance. This does not seem to help as each VI seems to maintain the state of the one which ran before. Maybe I'm missing a step?
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Hi Ben,
I actually read your document for another puzzle and it worked well, I think largely because it involved subVIs which were meant as separate threads. In that case, I used methods to alter inputs while the VI was "running."
In this case, as you know, my SubVIs are not looping inside, they are instead single calls but they do need to maintain the state at the end of their previous call, adding to the data they're tracking after they are called subsequent times. I tried the "call by reference" to call them each time. Below is a screenshot of the VI used to create the occurances and a SubVI used to execute each occurance, this subVI is embedded inside a while loop which I did not show here:
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Create Multiple tasks for Single Item in List using state machine workflow in sharepoint

Hi,
I want to create multiple create tasks for Single Item in List based on Assigned to column using state machine Workflow through visual studio
Here Assigned to column allows multiple users. so i have to create task for every user based on column .
I'm trying for this but i didn't got any solution
Please provide solution for this.

Hi,
According to your post, my understanding is that you wanted to allow multiple users to approve.
There are some articles about creating parallel tasks in state machine workflow, you can have a look at them.
http://www.codeproject.com/Articles/477849/Create-Parallel-Task-in-State-Machine-Workflow-in
http://msdn.microsoft.com/en-us/library/office/hh128697(v=office.14).aspx
http://social.technet.microsoft.com/Forums/office/en-US/b16ee858-4360-479a-a686-4ee35b7be9db/sharepoint-2010-workflow-creating-multiple-tasks?forum=sharepointdevelopmentprevious
Thanks & Regards,
Jason
Jason Guo
TechNet Community Support

Adding multiple states in state machine

Hi all,
I have a state machine with many states. I am using an enum to select state. I didn't add all the state in the enum at the beginning, so I am adding more statess to the enum and to the state machine as I go. I found the following pretty troublesome.
If after I made the first 3 state, and I realized that that next 3 states are very similar to the first 3 states. I want to copy duplicate the first 3 case all at once, instead of duplicating one case at a time.
If I duplicate one state, and the wrong enum is assigned to the state, is there a quick way to change it?
Are their anything out there that would help plan and keep track of the state machine?
Let me know if you have any cool tips to speed up state machine development, especially topic on enum and case structure (adding, deleting, multiple copy, etc).
Yik
Kudos and Accepted as Solution are welcome!

jyang72211 wrote:
after I made the first 3 state, and I realized that that next 3 states are very similar to the first 3 states. I want to copy duplicate the first 3 case all at once, instead of duplicating one case at a
If at all possible, never copy and paste code that is very similar to another piece of code! Try to write modular code. If there are several states that are almost identical except for a few slight differences, wrap those differences in a small case structure within the case.
If you ever find yourself tempted to copy and paste a diagram of code that is larger than a POSTAGE STAMP, reconsider!
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How do I add new data to the same file in a State Machine?

Hello,
I have a State Machine, with a State where 3 samples of data are collected in a For Loop. I would like to save this data in a file and keep adding new data to the same file each time I get to this state. The problem I'm running into is that each time I reach this State, my old data in the Excel file gets replaced with the new data instead of being continuously added in the same file.
Ive tried Shift Registers but I may not be using them correctly since my file keeps displaying only 3 new data points.
Any ideas will be appreciated!
Thank you, so much.
-Peter

Where should I place these shift registers? Where should I place my File I/O VIs? Is it possible to use the Write to Spreadsheet File VI in this situation?
Ive attached a very simple example of the problem. Thank you.
Attachments:
StandardStateMachine 2.vi ‏16 KB

Shutting down a queued event state machine with multiple parallel loops

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.)
I welcome any other feedback on my code as well, if anyone is willing to offer it.
My Program Requirements:
If the user presses the "Shutdown" button, the program should prompt the user with "Are you sure you want to stop the program?" and then either return to the Idle state or proceed to stop the program. Additionally if there is an error, the program should prompt the user with "Clear error and continue, or Stop program?" Then either return to the Idle State or proceed to stop the program.
Details of architecture:
The program consists of 3 parallel loops: (1) an Event Handling loop that enqueues various States to a State Queue, (2) a State Machine which enters the latest state that is dequeued from the State Queue, and (3) an Error/Shutdown handling loop which processes any errors in the Error queue.
During normal Shutdown, in the Event Handling loop the "Program.Shutdown" event case executes, and the States "Shutdown" and "Idle" are added to the State Queue. In the State Machine, the "Shutdown" state is invoked. A special error code "5000" is added to the Error Queue. In the Error/Shutdown handling loop, the "5000" error triggers a prompt that asks the user if they want to stop the program. If the user chooses not to stop, a notifier StopNotif is sent to the "Shutdown" state and "Program.Shutdown" event case with the notification "Go". If the user chooses to stop, the notifier sends the notification "Stop". The Event handling loop and State Machine are terminated if they receive the notification "Stop".
In case of error, the program behaves similarly: if the user chooses to clear the error and continue, the program returns to the "Idle" state.
HOWEVER - if the user chooses to stop the program, the program stalls. The notifier that is sent to stop the Event Handling Loop and State Machine cannot be read because the Program.Shutdown event case and the Shutdown state (which contain the "Wait for Notifier" function) are not active.
I have been able to activate the Shutdown state by enqueuing it in the Error/Shutdown handling loop. But I don't know how to activate the "Program.Shutdown" event programmatically, and thereby access the "Wait for Notifier" function inside it.
I tried to place the "Wait for Notifier" function outside the event structure, but then the Event Handling loop never completes. Placing timeouts on the "Wait for Notifier" and on the Event structure makes the program work, but I want to avoid using timeouts because I don't want to turn my event-driven program into a polling-based program. I'd also like to avoid using variables or property nodes to stop the loops, because that requires creating a control/indicator for something that the user doesnt need to interact with.
Thank you!
Solved!
Go to Solution.
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

Using multiple events structure inside state machine to control the Tab

Hi y'all,
Anne here.I have a Tab indicator in my front panel and I want to be able to control the flow of my program based on what controls I clicked inside the tab. I am using a state machine architecture and inside every state, I use an event structure to check for user interaction to determine the next state and what tab page is going to be displayed next. This means that I am actually using multiple event structures in my application and I use them in just one while loop, but just that they are not running in parallel since I am only using "one event structure per state" which means that only one event structure is running at one time. My questions is, programming technique wise, am I doing it correctly? So far, I am not facing any problem (I am still in the early stage of the project) but I want to check with you all first on your opinion regarding this architecture. Will there be any issue on using multiple event structures in a vi? Since I will be using a tab, and the controls available in the tab will be the controls that will control my event structure for that state, by right, there should be no issue. Am I correct to assume this? Is there any limit on the use of event structures? I have attached here a simple sample of the architecture that I am talking about for your reference. I have attached a 2010 version and a 8.6 version. Let me know what you think or any opinions that you may have.
Hoping to hear from you soon! Thanks so much in advance!
Cheers!
Anne
Attachments:
State Machine-Event Structure Sample_2010.vi ‏19 KB
State Machine-Event Structure Sample_8.5.vi ‏25 KB

Hi jak888,
I decided to use tabs cause I don't want to have subvi pop ups every time i need to perform the process in the state and show an update in the front panel. This is actually going to be more of an ATE where you will have to choose first whether the one using is the operator or the engineer. If the operator is logged in, she will proceed to choose what test to run (this state will have its own event structure). This part, I don't want a pop up, so what happens is that from Login page, if the user logs in as operator, the tab will automatically switch to the Test Selection page. After selecting the test, it will proceed to Start Test state and the tab will show the Result Summary page. If the user logs in as engineer, then a totally different tab will be automatically shown next and so on. By doing this, I will be able to show an update on the front panel objects without having the subvis pop up. I will also just need to use the call reference functions to call my subvis, making my Main VI more generic. The tab Page header will be hidden so the operator will actually not see that there is a tab and that there are a lot of controls and indicators cause they are hidden in the tabs and that page will only be shown based on what they selected from the main tab.
I appreciate your thoughts! thanks so much!

Execute multiple dml statements concurrently.

Hi all,
I have a requirement to execute multiple dml statements at the same time. I tried to achieve this using dbms_job, but failed.
I scheduled 3 dbms_job at the same time. Each job has a bulk insert statement, inserting into a single target table. The 3 jobs kicked off, but there were close a minute apart.
Is there any other way to achieve this?

You can launch 3 separate SQL Plus sessions, but how do you execute the dml statements at the same exact time?From my desktop machine, here's how I'd do it:
Create a dos batch file (runall.cmd for example) that looks like this:
start some_command.cmd
start some_command.cmd
start some_command.cmd
Then just double click on it. This will lauch some_command.cmd in 3 separate sessions. Each will be launched but will not wait to complete before launching the next.
Inside the batch file, some_command.cmd, you can have whatever you want. But it will probably be sqlplus.exe with some command line options (one of them a .sql script).
This is how I've used Tom Kite's "DIY Parallelization". But I normally would have a parameter (like a range or something) to keep the DMLs mutually exclusive.

Data acquisition in a state machine

I've recently learned how to implement state machines, but I have a question that I haven't been able to find an aswer to.
Question:
How do I record uninterupted data (presently i'm using the DAQ assistant to record a single channel at 10kS/s at 1kS intervals) without interfering with my state machine?
Background:
I have a time sensitive test setup (measuring pressure in a rocket chamber), and I'm using labview to both record a single pressure transducer as well as operate the valves (O2, N2, igniter, etc). I'm using a state machine Labview architecture (just learned how). Presently, the DAQ assistant sits in the "Idle" state, and timers (valves need to be turned on at specific times) and manual buttons control when the other states are activated. I have a 10ms timer controlling how often each state is run, and this is the root of my concern.
Main concerns:
I'm worried that:
1) I'm forced to change my data recording to 10ms intervals to match the 10ms timer, and
2) The 10ms timer will interrupt my data recording when it's in another state.
It's very important that the pressure data is recorded without interruption but that I have high time resolution in controlling my valves as well.
Thoughts:
1) Maybe I put the 10ms timer in the "Idle" state only, and this way the other states won't interrupt the data acqusition
2) Maybe there is a way to completely isolate the state machine for controlling the valves and the data acqusition. I'm not sure how to do this.
3) People on the forums have been talking about Queuing their data acqusition, but I'm not sure how this would benefit my situation.
Thanks to everyone for their feedback!

The data acquisition and state machine timer do not have to be equal, you should however have the same data write rate as you have data read rate, otherwise over the course of long running programs you can build up a large buffer of data to be written using a lot of memory, or lose data.
Your data acquisition should be continuous, the most common way of doing this is every time you receive data write it to a queue, then when you are in other states except your data write stage you simply build up data in the queue that is to be written when you enter the write state again.
Think of it as traffic reaching a set of lights:
The traffic represents the data acquisition, there is a constant flow of it always coming through, the state of your state machine is the lights, green is the data write state clearing the queue, red is when in any other state, letting the traffic build up behind the lights.
It is just important that the light is green long enough to let the traffic not build up too much, otherwise you have a jam.
EDIT: For the basics of how queues work, look at the Queue basics example from the example finder.

Data acquisition & state machine

Hi all,
I am working on a project that is capable of data acquisition, analyse, and record processes. I have to acquire data of temperature from 8-32 channels and that of pressure from 7 channels. After analysis, I have 48 outputs. I want to record raw data (acquired) and analysis data at the same time.
1) Is it possible to record two text files (raw data and analysis data records) at the same time?
I also want to adjust acquired sample rate but I have doubts about utilizing it in a state machine. For now, I have just used time elapsed function to acquire data once in 60 seconds.
2) How could I set sample rate of acquisition except using time elapsed function?
I also have one more doubt about timing. If I needed to acquire sample once in 60 seconds, but the analysis took more than 60 secs, what would happen?
3) How can I prevent data loss in this case?
I have not prepared a user interface yet.
4) How can I utilize it? Do I put graphs and indicaters in the same VI or is it better to prepare another vi just for user interface?
Thanks in advance
Egemen
Attachments:
Program.llb ‏433 KB

Hi Egemen
-          If we need to acquire data and analyze it at the same time we recommend the architecture producer-consumer to prevent data loss, and yes you can record two text files at the same time. Please take a look to this architecture.
-          http://www.ni.com/white-paper/3023/en
-          Basically you use the first loop to acquire data and the second one to analyze and record data (using queues).
-          https://decibel.ni.com/content/docs/DOC-2431
-          You can also find examples about this architecture at the developer zone.
Regards

Relay Testing with State Machine

Hi,
Yesterday I very kindly had some help from "crossrulz" in setting out the following procedure. Today, the National Instruments representative called and said I should implement my programme as a "State Machine", which I have attempted in the programme attached. I was wondering how I might now implement the procedures 3 to 5 in this State Machine format as it seemed very complecated in the brief time we had.
What I am trying to do is test relays, using an automated test procedure.
The procedure takes the following steps:
1. A NI9472 DO card and transistor drive turns the relay on/off via energising the coil (needs the time period to be variable).
2. Counts how may cycles the relay contacts have operated, this will easily be in excess of 100,000 cycles.
3. Every 100 cycles (again variable), the contacts are held closed, the load circuit (the current the relay is switching, which will be 15A at 30V) is disconnected, via another relay and a measurement is taken via a separate four wire method. This consists of a 6V supply being placed across the contacts (switched in again via a relay) with a 1A current flowing through the contacts, the voltage drop across the contacts is then inputted into the NI AI NI9219 card (this is in the region of 10’s of mA) and is directly proportional to the contact resistance, which is what I want to measure.
4. The measurement is taken and stored and the measurement circuit disengaged, the load circuit re-engaged, and another 100 cycles is counted before the process goes back to stage 3.
5. This process goes on until the relay fails and hopefully a large set of contact resistance data is gathered.
I have no real experience with NI Labview.
I have looked at the basic academic tutorials and have come up with the following programme for stage 1, however I can't get the DAQ Assistant to output every cycle
Would this be a very difficult programme to implement for the novice? The academic tutorials seem straight forward but when I try to do someting it seems very difficult.
Hoping someone may be able to help, thanks
Andy
Solved!
Go to Solution.
Attachments:
Relay Test State Machine.vi ‏207 KB
Relay Test State Machine.vi ‏207 KB

Hi James,
I've tried to implement some logic as suggested. I can now get the 1A coil to engauge after the nth cycle and I think it's taking a measurement, but can't seem to get the 15 A coil to disengauge at the same moment, which is crucial else the measurement will be across 16 A rather than just the 1 A. Any ideas? I just want to get it working so we can get started with testing.
I'm going to get my supervisor to book me on a course at Newbury for future projects, it's very difficult to pick up of your own back.
Kind regards,
Andy
(Helps if I attach it)
Attachments:
Relay Test State Machine.vi ‏209 KB

How do you create array of enums for transitions in a state machine?

Hello,
I am trying to build a state machine, but, I am struggling with understanding the methods for determining which state to transition to next. In other words, I have several states, but, I don't want to go in any particular sequence. If I have states numbered 1 through 10, I want to be able to go 1-4-2-5-6-2-6-1-10 etc. in no particular order. I want the transition to the next state (and actions) to be determined by the streaming data, which can be random and require access to any of my 10 states at any time and in any sequence.
I saw this picture on the "Application Design Patterns: State Machines" white paper, but, it leaves out some important details. How does one create the structure in BLUE shown in 3C? When I try to create this array of enums, all of them are the same. I am not able to make a list of different enum values. In other words, when I type in "2", then, all the values in the array display as "2."
There is a nice, simple video example of a state machine for dispensing soda for $0.15, however, this state machine moves in a single sequence, from 5 cents, to 10 cents to dispense; it does NOT illustrate how to select a state "out of order." I need to understand how a state machine can move from "5 cents" state to dispense directly, with the addition of 10 cents to the "5 cents" state.
Can anyone suggest a really good tutorial on how to make the selector work in a state machine? I have been reading some of the available material on ni.com, but, I can't find a good detailed explanation of how to do it. I remain confused.
Or, can you just explain how they created the BLUE array in the attached picture? Maybe I can figure it out from there.
Thanks,
Dave
Solved!
Go to Solution.
Attachments:
next state.jpg ‏75 KB

Hi Kathryn,
Yes, this is EXACTLY what I want to accomplish...
So it would basically run:
State 1
Read input
Determine next state (say 3)
State 3
Read input
Determine next state
State
Read input
Determine next state
And so on...
But, I am quite new to programming Labview state machines, and can't figure out how to even start when the sequence of states is random instead of fixed!!! I can do 1,2,3,4, like the vending machine VI example, but, not 1,3,2,2,2,5,2,1 etc. based on external input. Is there some simple example case I can study? I can't believe I am inventing this for the first time.
"select the state to run"
But, HOW do I do this??????? This is exactly the question I am asking...how is this done? Please see the attached 3-state system....how do I hook this up???? I am totally lost here...can you help me understand how to wire this thing?? In this simpe RED/GREEN/BLUE case, my input is just the number a user would input on the front panel.... Apparently, there are two files necessary... a vi and .ctl??? What is .ctl?
Thanks,
Dave
Attachments:
forum nov 12 red green blue.vi ‏7 KB
forum nov 12 red green blue.ctl ‏5 KB

New LabHSM Toolkit - Agile development of complex event-driven maintainable LabVIEW applications with active objects / actors based on a universal Hierarchical State Machine / statechart template.

Dear Fellow LabVIEW programmers:
Most of the systems you deal with are reactive. It means that their
primary function is constant interaction with their environment by
sending and receiving events. But most likely, they can have something
happening inside them too, even when they are not processing messages
received from outside. So, such systems have to continuosly react to
external and internal stimuli. Right? Moreover, most likely, they
consist of subsystems that are reactive too and, in turn, can have
their own "life", to an extent independent from other parts (with
which they still communicate, of course). Reactive (event-driven)
systems are more naturally modeled with active objects. So, why then
should we try to model and code them with GOOP and its passive
("dead"!) objects?
"Flat" State Machines have been known for decades to have severe
limitations. It's been more than 20 years since Dr. Harel invented
Hierarchical State Machines (statecharts) to fight those limitations.
Then why does NI still tout the same old good Moore FSM as the
ultimate tool for event-driven programming in LabVIEW in its $995
State Diagram KIt?
The LabHSM toolkit we are happy to present, makes it possible to
easily create and then maintain complex event-driven applications in
LabVIEW as a collection of HSM-driven active object VIs using a higher
level of abstraction and agile software development methodologies.
These active object VIs are created based on a universal Hierarchical
State Machine ( HSM or statechart ) template. So. all your code looks
similar regardless of its functionality!
We all love just jump to code, right? However, to be good boys, we
need to do design first. Then implement it in code. If the logic is
modified we need to redo the design first and then redo the code. When
using LabHSM where behavior information is abstracted into a separate
HSM data file editable with a supplied editor, there is no need for
coding separate from design any more. The modified behavior becomes
code automatically as soon as the HSM file is saved. Design is code!
The implementation basically follows Dr. Samek's Quantum Programming
paradigm. (see http://www.quantum-leaps.com). However, as already
mentioned, LabHSM stores the behavior information in a file separate
from the code itself. It also adds state dependent priorities to
events, a separate queue for public events/messages, and, of course,
some LabVIEW specific code like capturing front panel user events and
putting them into the private Events queue. Communication and
instantiation functions are also rather specific for LabVIEW.
It is available for UNLIMITED PERIOD trial. Please visit
http://www.labhsm.com for details and download. The site also contains
references which you may want to check to learn more about
hierarchical state machines and active object computing.
Since this is our debut we will appreciate any comments and
suggestions. Our contact information is available on our site, of
course.
Have a G'day!

Symtx is currently hiring the following position. Please contact me if interested.
Amy Cable
Symtx, HR
[email protected]
Symtx, the leading supplier of functional test equipment, hires the brightest & most talented engineering professionals to design & manufacture complex custom electronic systems for advanced technology leaders in the defense, aerospace, communications, medical, transportation & semiconductor industries. Symtx’ challenging & dynamic work environment seeks to fill openings with highly qualified electronic engineering design professionals.The ideal candidate will be responsible for defining the requirements, software design and code development, and integration of test control software for custom functional test systems. Candidate should be familiar with data acquisition concepts, instrument control, complex test, measurement and calibration algorithm development and definition and implementation of control interfaces to hardware. Prefer familiarity with instrument control via GPIB, VXI, MXI, RS-232 desirable. Requires BS/MSEE and 3 -7+ yrs of experience in one or several of the following test applications in a Windows NT/2000/XP environment using Labwindows CVI, TestStand, Labview, Visual Basic, C++ and knowledge of RF systems is a plus. Job responsibilities will include software design, development, integration, team leadership, and interfacing with customers( includes PDR’s & CDR’s).

Producer consumer vs state machine

Hi there,
I have been on and around for quite a while to understand how can I re-design an application, which was originally built using a mix of sequence structure, while loops and event structures. And now I am making a newer version of the same application, for research purposes, while learning the LabVIEW techniques. Earlier I used LabVIEW versions 5 and 6 to make simple programs for fuzzy logic and neural networks. And that's not a good reference.
Ok, after learning that Producer Consumer (PC) and Standard State Machines (SSM or SM) are two new approaches for a better (scalable, flexible and efficient) coding as suggest by veterans, in one thread where I asked about another issue, I have started digging into this topic and now I am on a point where I have to implement it finally (spent pretty much time in the learning phase).
I have several questions.
To start the discussion, I would give a brief description of my application.
It's a networked application, where the network communication happens using DataSocket (one reason to use LabVIEW as the environment).
We are talking about the client application, which communicates with other applications on remote computer, via Internet.
User interface involves a tab control, with several pages-
On startup, the controls/indicators (now onwards referred as controls only), are initialized, datasocket connection is checked (rather internet is checked, and a connection established with the remote datasocket server) (page 1)
If connected to the datasocket server, the user selects Login/Registration (page 2)
Login and/or Registration happen on page 3/4
Then the user sees a table of remote users to connect to (page 5)
Upon selection of a remote user, and after clicking on "connect", the user will see a video indicator, with a lot of other controls. (page 6)
On this page with video indicator and controls, the user has a lot of activities, in which many messages are sent and received to/from the remote machine.
the user may disconnect and go back to page 5, and log out and go back to page 2 and so on.
I hope this is clear.
I have thought about two different ways to do this application. Using PS or by SSM.
In the attachments, I have given a diagram (with errors, of course, because of unlinked controls), for each of the approach, plus the original application's diagram.
I hope this is sufficient for anybody to understand my case and give suggestions.
I am looking for suggestions about which is a better model for my type of case. I have been to discussions like this one and saw that there are many issues regarding dequeue in PC model. So I am curious to know if SSM is a better and latest model or it's more primitive? Which looks better for my application's performance?
Thanks ahead!
Vaibhav
Attachments:
OldDesign.vi ‏41 KB
PCDesign.vi ‏42 KB
SSMDesign.vi ‏46 KB

Vaibhav wrote:
@ Harold
Thanks. Any suggestion how can I start and stop that loop in parallel with other loops? Like, if some event occurs, the loop should start execution, and keep on moving, while other events are being traced and executed.
In those examples where you had a while loop inside a case structure, that bit of code will only execute one time. It will immediately read the boolean at the start of the program, if the value was true before the porgram started, then the while loop will run. Once that while loop stops, the case structure will end. It will never execute again unless you completely stop and restart your program. If the boolean is false before the program starts, the false case will execute immediately. Nothing happens since it is empty and it is done, never to run again (unless you stop and restart your VI) You should turn the structure around. Put the case structure in the while loop. Make sure you put a small wait statement in the loop so that it doesn't run full speed eating up CPU cycles just polling the status of the boolean.
@ Ravens
Thanks for the detailed comment.
One thing I would clarify. The user will not be able to switch between the pages using the tab control. The program will direct appropriate page to the user. I kept the tabs visible just for your idea of the pages. Sorry, I didn't mention that.
Do you think it's still a bad design?
If the tabs will be hidden or disabled, you will probably be okay. I wouldn't call it a bad design. I wouldn't do it that way. But as long as you understand the possibility of problems and prevent that. Especially some time down the road when you modify the program in some other way that could lead to a problem because you forgot about the dependencies of the event structures on the state of the state machine.
Yes, I agree about only one event structure to handle all the events. But since the user will not be able to click somewhere else, other than those possible controls, I thought to keep it like this.
I thought the events are captured only if we are in that case. I think I am wrong, right? Events are captured at any time, even if the case has never executed before, or will never execute. Ok, The events will be captured, but will not be executed until in that case.
And that's the reason why I have two separate event structures, in two separate phases of the program.
Because, prior to page 6, the events will occur sequencially. The user will click somewhere, then some message will be transmitted over DataSocket, then some message may come , then again some user action and so on. But, when the user starts using page 6, there will be parallel process of user controls events and actions, and incoming messages and corresponding actions. For this, in the page 6, I need a different kind of execution. So I separated the two event structures.
At first I thought to have SSM, and then I thought to PC, just because I can have two separate parallel processes - one for user events, and another for messages (because that way I can take maximum advantage of message tracking). But looking at other complexities, I find SSM more appropriate. Can you please tell me how can I have my message loop and events loop parallel to each other and just one event structure?
You can have a dequeue function in your state machine loop and have it be a consumer loop. Use a timeout on the Dequeue. If there is a timeout, have the statemachine execute normally after that perhaps just passing the enum wire straight into the case structure of the state machine. If it doesn't timeout meaning you got a message, then look at the message that is dequeued and act on it. Perhaps it means ignoring the enum coming in from the shift register and changing the enum to something else to feed into the case structure of the state machine. Attached is an example
Attachments:
PCDesign[1]_BD.png ‏6 KB

How to return the result set of multiple select statements as one result set?

Hi All,
I have multiple select statements in my stored procedure that I want to return as one result set
for instance
select id from tableA
union
select name from table b
but union will not work because the result sets datatypes are not identical so how to go about this ?
Thanks

You have to CAST or CONVERT (or implicitly convert) the columns to the same datatype. You must find a datatype that both columns can be converted to without error. In your example I'm guessing id is an int and name is a varchar or nvarchar.
Since you didn't convert the datatypes, SQL will use its data precedence rules and attempt to convert name to an int. If any row contains a row that has a value in name that cannot be converted to an int, you will get an error. The solution is
to force SQL to convert the int to varchar. So you want something like
select cast(id as varchar(12)) from tableA
union
select name from tableb
If the datatypes are something other that int or varchar, you must find a compatable datatype and then convert one (or both) of the columns to that datatype.
Tom

Multiple same states in a state machine

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