read from measure Makefile slow while loop

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• Series of reading and DAQ in same While loop

  Hello world

  I have a while loop that has a DAQ reading and a reading series of VISA.

  DAQ readings slow while loop for series com & therefore the iterative nature of the measures to constantly check byte-by-byte (for the full range of the code: 22 bytes) does not work. (it will check 8 bytes, 24,.. etc. because more bytes is collected in a buffer before it can browse new loop.)

  Is it possible to synchronize these two data acquisition devices?

  Data acquisition speed is fast enough, so if there is a way to keep the series bytes in a queue and take only the first 22 bytes for every while loop iteration?

  Thank you for your help. I can't join VI, but I can give you a reference image.

  I recommend having separate loops of data acquisition and reading series.  If you simply connect the latest value, the local variable is great for sending to playback in series to the other loop for logging.

• [begineer] reboot a 'while' loop reading the serial port

  Hello! I read some data from a COM port. I want to read my like this "%d S. the unit will send data continuously and depending on when I push the button run in labview, it can start to read data from the middle (%d is a four-digit number). as: 23 S 15'

  "whenever the first character of my data is not of", I need to restart playback. I read the data in a while loop. so I need to stop the while loop. From what I found on the internet, I used a case, another while loop and shift registers.

  but in some way I'm stuck inside the while loop. My VI is attached. Thanks in advance and sorry if my code is a mess!

  PS: what should I do if the bytes I get to the port is variable? use bytes to the port?

  The device sends a character at the end of the line at the end of each message?  You are currently Setup to do this by activating the stop character (currently set to end of line/10/0xA).  If this is true, then simply set the bytes to be read on the VISA to read something rediculously high.  It will stop playback when it finds this termination character.  From there, you just have to check for the correct format.  If this isn't the right format, ignore him.  Otherwise make your recording.

  I managed to clean up your code a bit on this basis.

• 2 while loops can work at the same time?

  I have two while loops in my program; We can read the data and the other does nothing until I hit stop on the first. I want the first and the second to run out of the time constraint, I have for it when I hit the Start button to always run. I use a DAQ and transfer data from one to another while loop. See the attached file.

  Main issues:

  How to tie the Start button?

  How to get the second loop to work with the first?

  Thank you

  Your problem is that the loops are dependent on the data.  If you want to run two loops at the same time, they cannot have wires linking one to the other.  Focus on the architecture of producer/consumer .  It uses queues to send data of a loop to the other.

• While loop stops unexpectedly

  Hello world

  I have a problem with while loops.

  Im trying to write a program that allows me to control the temperature of a hot plate, using as a starting point one of the examples in LabVIEW (basic series writing and reading). So basically the program sends an order asking the real temperature of the heating plate and it then reads a response with the State, then the user writes a temperature (the sub - VI creates the command that is sent to the cooking plate), then he reads a confirmation response. the while loop is to monitor the temperature and change it if necessary

  Sometimes it works for about 30 seconds and sometimes for a few minutes, and then everything stops playback, I don't get the error messages, it stops just a response.

  The hot plate is a pro H550 MS7 and im using a USB to RS232 converter

  PD, I'm pretty new using labVIEW, sorry for my bad English.

  Greetings and thanks for the help

  Bob_Schor wrote:

  Found the manual.  Here is a summary (edition - in fact, it is essentially all of the manual, just condensed and without 'images'):

  • The statement format: prefix, Instruction, data frame, Checksum
  • Command: Prefix is 0xFE
  • Answer: The prefix is 0xFD
  • Add at least 50 msec between pairs of bytes
  • Data frame, send high and low bytes
  • Checksum = sum of the instructions, the frame data, but not prefix
  • Commands and responses seem to be mainly sequences of 6 bytes

  OK, this helps a lot.

  The first issue with the OP code: turn off the stop character.  The protocol uses binary communication protocols.  The stop character is only useful for communications ASCII protocols.  Nor if he was being a 0x0A in data, VISA Read stop reading right there because it's the stop character and it is enabled by default.

  Second, always do not have need of the bytes to the Port.  You know what you send and you know what should be the answer.  Therefore, suffice to say the VISA of reading to read the required number of bytes.  If your delay is long enough, you do also not waiting for him by saying the VISA must read the number of bytes to read.

• Control and Simulation in a loop / while loop with TCP/IP reading / writing of synchronization

  Hello, I have a problem with reading TCP/IP and written in two loops. The problem is NOT to get the two loops to read and write to and from the other. This has been accomplished. My problem is when I run control and the loop simulation on my laptop and the while on a RTOS remote on the controller on-Board of LabVIEW in a remote PXI chassis, the while loop the remote system running on four 4 times faster than the loop control and simulation on my laptop. In other words, for each iteration of the loop control and simulation on my laptop, there are 4 four iterations of the while loop on the remote system. I need to know how to get a degree of kinship (1:1) with these iterations of the loop. When I run a longer simulation in real time, say 10 seconds, the control and Simulation loop begins to slow, i.e. the simulation time slows down until it is no longer in real time and the "Late Finish"? Parameter is set to true and the LED lights and continues to stay lit. At this point, the system destabilizes due to what I believe is being well sampling rate too discreet and I have to end the simulation. How can I get a ratio of one to one between the loops and also to avoid slowing the loops causing destabilization?

  To give an overview of my application, I implement a control system in a network, seen in "image2.png". This is achieved using my laptop as a subsystem 1. Reference signals are generated from the laptop and the error signal is produced. Control measures taken and the control signals are sent via TCP/IP to the remote system. Position feedback is returned, and the process repeats. My system has Core I7 Procs w / 3 GB of RAM, up to 1 GB/s speed via ethernet and LabVIEW 2011 installed with all necessary modules and networking tools. The attached VI Custom_Wireless_Controller works on my laptop. The remote system I'm working on that has the 7830 NI R Series with FPGA card. OTN runs on the PXI chassis with an enbedded controller that has networking capabilities of up to 100 MB/s via ethernet. I use the FPGA for the acquisition of data and apply control signals to my plant. The plant is the PCE twist connected to the FPGA through the cable of the ECP - RIO of NOR. Subsystem 2 is this side of the CNE. The FPGA collects position, he sends to the controller via the network, receives signals from the network drive and writes signals to the plant power amplifier that operates the plant. This process is repeated and the VI and is titled Custom_Wireless_Plant.

  I appreciate the help really and look forward for her and for any question!

  Well, the first step is to understand what you have set up right now. Your control and Simulation loop on the side of the controller is configured as 'Runga Kutta 4' and you have a loop timed on the other side. In addition, you have the primitives of TCP/IP on the control and the Simulation diagram and means he will perform (a message) on the size of each minor step, which in your case is 4.

  So, you have two options:

  1. replace the Solver side controller Runga Kutta 1 (this must synchronize loops)

  2. hold RK 4, but create a Subvi around two primitives of TCP/IP and configure from the VI to run than the major (continuous) step-size. If you do it right, you should see a 'C' on the upper right part of the VI you have created.

  Please let me know if what I said is not clear...

• global variable functional to read and write data from and to the parallel loops

  Hello!

  Here is the following situation: I have 3 parallel while loops. I have the fire at the same time. The first loop reads the data from GPIB instruments. Second readers PID powered analog output card (software waveform static timed, cc. Update 3 seconds interval) with DAQmx features. The third argument stores the data in the case of certain conditions to the PDM file.

  I create a functional global variable (FGV) with write and read options containing the measured data (30 double CC in cluster). So when I get a new reading of the GPIB loop, I put the new values in the FGV.

  In parallel loops, I read the FGV when necessary. I know that, I just create a race condition, because when one of the loops reads or writes data in the FGV, no other loops can access, while they hold their race until the loop of winner completed his reading or writing on it.

  In my case, it is not a problem of losing data measured, and also a few short drapes in some loops are okey. (data measured, including the temperature values, used in the loop of PID and the loop to save file, the system also has constants for a significant period, is not a problem if the PID loop reads sometimes on values previous to the FGV in case if he won the race)

  What is a "barbarian way" to make such a code? (later, I want to give a good GUI to my code, so probably I would have to use some sort of event management,...)

  If you recommend something more elegant, please give me some links where I can learn more.

  I started to read and learn to try to expand my little knowledge in LabView, but to me, it seems I can find examples really pro and documents (http://expressionflow.com/2007/10/01/labview-queued-state-machine-architecture/ , http://forums.ni.com/t5/LabVIEW/Community-Nugget-2009-03-13-An-Event-based-messageing-framework/m-p/... ) and really simple, but not in the "middle range". This forum and other sources of NEITHER are really good, but I want to swim in a huge "info-ocean", without guidance...

  I'm after course 1 Core and Core 2, do you know that some free educational material that is based on these? (to say something 'intermediary'...)

  Thank you very much!

  I would use queues instead of a FGV in this particular case.

  A driving force that would provide a signal saying that the data is ready, you can change your FGV readme...  And maybe have an array of clusters to hold values more waiting to be read, etc...  Things get complicated...

  A queue however will do nicely.  You may have an understanding of producer/consumer.  You will need to do maybe not this 3rd loop.  If install you a state machine, which has (among other States): wait for the data (that is where the queue is read), writing to a file, disk PID.

  Your state of inactivity would be the "waiting for data".

  The PID is dependent on the data?  Otherwise it must operate its own, and Yes, you may have a loop for it.  Should run at a different rate from the loop reading data, you may have a different queue or other means for transmitting data to this loop.

  Another tip would be to define the State of PID as the default state and check for new data at regular intervals, thus reducing to 2 loops (producer / consumer).  The new data would be shared on the wires using a shift register.

  There are many tricks.  However, I would not recommend using a basic FGV as your solution.  An Action Engine, would be okay if it includes a mechanism to flag what data has been read (ie index, etc) or once the data has been read, it is deleted from the AE. 
  
  
  There are many ways to implement a solution, you just have to pick the right one that will avoid loosing data.
  

• While loop with reading of text file - calendar of events in a given period

  Hello world.

  I created a program that if serial interface via a port to a syringe push in my lab. Currently, the program reads in a text file-flow rate values and sends them to the pump, one by one, through various commands. I need to ensure that whenever a new flow rate value is sent to the pump, it does in a specific/hard time for a while. I.e. every 0.1 seconds, changes in flow rate and must are active until the next period. I tried to use a timed loop and I think I've succeeded, but it hogs system resources, so I was wondering if there was a way to do it using the number of cycles or something of this nature. I just started using LabView, so I'm slowly getting the hang of it (easy when you watch my VI!)

  See attached VI. I took orders from serial port and have instead orders display in an indicator. The nested and densely populated while loop contains the commands that need to be completed/last during the period (like 0.1 second).

  Thank you for your time and help!

  -Phebotalus

  Hi, you should read some introductory material on LabVIEW to down the idea of the stream.

  Basically, the data flow in the wires from left to right, and any node will not work until it has reached all of his contributions.

  The thread of the error is the best way to run data streams.

  ***

  In your VI I use data wires, their execution through structures, and forcing the structures to run in the sequence.  Using a structure of sequence you mentioned in your next post will force the two scripts to execute in the order of (the only one we discussed to be in race condition.)

  Similarly, for brevity, I would wrap the EMO and she is business structure in a single sequence and force it to run last using stream.  In this way the user has the most possible time to decide to hit the EMO before she is called by the application.  As it is now, it most likely is interviewed at the beginning of the loop, so if it's the exchange value you won't see results until the next loop.

  When running in execution of highlight you see the order of data flow, but that is not guaranteed to be the same for a normal performance, where the use of the data stream.

  ***

  The counter tick account ms up to a very large number and then "says" reset and start counting again.  I know you want to START the loop as close to every 10 ms.  Yes, using data flow, take the number of cycles first, perform actions, then return the number of cycles.   The second time of the tick read that you are in a nested loop that does not stop until you get 10 or more difference on the number of cycles.

  And, on the off chance that you must achieve "return" on the tick counter comes stops the nested loop then move.  (if the second measurement is less than the first, then the tick counter handed.  If you miss this situation while you'd have to wait a long time for the condition of the difference > 10 in the reunion, basically locked in the loop.

  ***

  You could put the EMO sequence, we have seen, in line with data streams.  Before or after the second control of ticks will not make much difference in terms of 10ms.  I would put it after checking the tick, again give the user more time to hit the EMO if necessary.

  ***

  I put in a queue for the stream error and removed the other stuff.

  LV2010

  Check out some of the LabVIEW intro docs, they are online, they discuss these issues and much more.

• DLL slows parrellel while loop

  Hello

  I am changing a VI I wrote, to work with another piece of equipment. Communication tends to work directly through labVIEW. My new equipment provided with a driver/dll library and now I have many layers before reaching the material (LabVIEW-> driver-> software-> the measuring equipment). I have some time this account down to run alongside my Subvi who manages my method of measurement of the loop. As I put in place the screw that call DLLs that count - while loop slows down in the same frequency, I'm calling the dll. I've changed the "Run in the user interface thread" setting to the "Run in any thread" option in the call library function node. In fact, which got rid of my problem about 90%. But my meter still comes in a few seconds at the end. I wonder in what sense the crux of library function call delayed a seemingly parallel thread?

  Any suggestion on the place where to continue searching for a fix?

  Welcome them

  / Lorenz

  It is hard to tell what might work without knowing your DLL and what he actually did, but I see something in your loop that will force LabVIEW to toggle the user interface thread! The property node to update the text of the start_method th button will ALWAYS force a change of context for the UI thread. If you can avoid this really should not be possible for the DLL block your loop more. At least try to not update this property if it needs to be changed with regard to the previous value and not at each iteration of the loop.

  A guess is that the DLL actually interfaces to ActiveX code somehow. LabVIEW initializes its ActiveX environment to run in the UI thread, because it is the only safe thread system in LabVIEW to perform many threaded ActiveX components or when the data marshaling is involved. If your DLL tries also to connect to an ActiveX interface, it will be forced to go the UI thread that explains how to access the property in your loop can get delayed.

  And another problem you have is the moment of software. count you down the loop increments of 10 ms, but Windows will be hardpressured for hard real-time performance. While you are not using the "wait until the next ms Multiple" to take account of some jitter, if the loop is blocked for more than 10 ms through an external resource, you will actually jump an interval.

  Better would be to calculate the time elapsed directly reading the timer tick before entering the loop, then use the output of graduation of timer her to "wait until the next ms Multiple" to calculate the difference. Dividing this difference by 10, and then adding your counter value initial this result would give you the same value that you feed your VI calculation, but what about the real system clock, not a counter loop running asynchronously with questionable interval.

• What is READ the array returned by the DAQmx meter? How can I know the two functions DAQmx READ data stream in the same WHILE loop?

  I have a question about the order of execution.  In the WHILE loop, I have two things to measure, period and tension using the DAQmx READ functions for voltage and the meter.  In the end, I want to collect these data as points almost simultaneously as possible, as a pair and then send them together to another piece of code (not shown here) which them will result in some sort of command for an engine.  It would be run, and then I want to perceive the tension and the period at a time later and do the same thing.

  (1.) I'm a little confused on what the meter of the READ function is back because it's a table.  What is a picture of?  I thought that it was up to the value of the individual periods between rising edges.  The output of the counter 1 DBL d's a table. How many elements in this table, and what determines the size of this table?  Are the elements of the array the individual delays between the edges?  How many values are stored in the array by executing?   We take the AVERAGE of the last 15 items, but do not know if we are throwing some of the data or what.  How to understand the composition of this painting?  How can I change the composition of this painting?  Is it possible to measure only one period at a time, for example the time between TWO edges?

  2.) Will this WHILE loop execute as it gathers tension and a "period table ' (remains to be understood by me) by TIME running in a loop?  In particular, we want that the value of the tension associated with the value of the AVERAGE of the period "array", so we can use two data items to create orders of next control every time that the two values are reported.  The structure for the delivery of vi will be attached data in pairs like this?  I understand that one of the READING functions run not before the other function of READING in the WHILE loop.  I want that the period "means" and "strain (Volt) collected at the same pace. This vi will he?

  Thank you

  Dave

  Hi David,

  I suggest including the DAQmx Start Task function. If it does not start before the loop, it starts the loop and work very well, but it is not as fast and efficient. In the model of task status, task wiill go to run the checked each iteration of the loop and then back the time checked running when it restarts.

  The status of the task model: http://zone.ni.com/reference/en-XX/help/370466V-01/mxcncpts/taskstatemodel/

  Kind regards

  Jason D

  Technical sales engineer

  National Instruments

• Measurement of time in a While loop

  Greetings gentleman;

  I'm kinda new to Labview, and although I sought an answer without assignment, I wasn't able to find one.

  So here my question, I would like to know how I can measure the time a loop sequence, in other words, what time is my point of view VI to run the main loop together?

  A little explanation, the attached VI tries to be a Markov chain, it takes some values in the first case structure based on the previus loop, then, if the values are correct, it passes to the next step and so on. It's pretty simple, and yet, my problem lies in the measurement of time. Since it is a 'distribution', it would take infinite time to execute a simple loop if it does not fulfill the characteristics, but it is scheduled to meet them so an average time should work.

  So, if you look to the while loop, should the big one, I want to measure how long I take for a ride.

  Thanks for the help, I'd be happy to read some ideas on how to measure this.

  Kind regards

  IRAN.

  You will find examples in the example Finder OR by searching for 'speed test' or ' reference '.

  Essentially, you create a flat sequence structure inside of your loop. In the first image, you measure the current number of cycles. In the middle frame, you run your code. In the last image, you measure the number of cycles again and subtract the first number of this. This gives you the run time to execute the code.

  You can see a page of the community about it here.

  There is a high-resolution time tick count VI hang out somewhere which is great for benchmarking and improving efficiency, used instead the number of cycles (ms) primitive.

  Edit - remember where he was

  https://decibel.NI.com/content/blogs/EvanP/2010/10/04/tick-count-us--microsecond-timing-granularity-...

• Possible timeout in VISA read/write in While loop

  As the title says, I have a while loop that is constantly written followed by reading using VISA read/write.  I'm waiting for buffer correspond to a certain one, which the true value would end the loop.  In this loop, I have an indicator showing how many times he runs. All of this is repeated in another while loop.

  My problem comes the counter arrives at 10, then stops at the "write" command.  Do not know why.  I tried to increase the time-out of the instruments, but nothing has changed.  I added a delay of 10ms in loop, which also has not changed anything.

  For reference, I use a tektronix scope series 3000 of the MDGS and checking its state of relaxation.

  You said chill to read earlier!

  But it is not supposed to have to write it either.  Experimentally, access all VISA nodes, right-click and choose the Mode of synchronous i/o.  Make it synchronous instead of asynchronous.  The watch symbol will disappear from the top right corner.  See if that changes anything.

  What kind of serial port are you using?  What is an integrated in the PC?  A USB to serial port adapter?  Makes the chips on that, Prolific and FTDI?  You can try with a different serial port or a brand of adapter?  A lot of people have had problems with prolific chips.  And I have also heard of people having problems using adapters who had fake chips in them.

• void / vi... read vi inside while loop

  Hello

  I'm new to Labview... My main Vi keep reading data from serial port and parks (in words) in a table (put all in a while loop)...

  The table is also inner while loop... Now I still want to analyze this (element by elemnt) table and create an another VI who takes this array running as input... so the new VI should simply have this table entry... but the problem is that I can't see the data running in new vi... .any suggestions... ??

  ebuckbuck wrote:

  Thanks Apok...

  I'm not sure hoiw reference books here as when I create refernce of table VI main (24 sep... (VI)... it does not produce yet of any substance in following VI (who called)... Attached are my two files... .and I just want my main VI as for the output as array2 Terminal...

  Thank you very much

  ebuckbuck

  in this example, we want to move an indicator (main.vi) digital of the second loop (sub.vi)...

  

• How to control a VI (with a while loop and a structure of the event) from an another VI

  Hello

  I have the main VI which I want to be driven from an another VI. But I can't do that and I don't know what is happening.

  For example: VI main, I have a while loop with a structure of the event, there is a Boolean controller controlling a Boolean LED, which is inside the structure of the event. And the other VI, there is just a Boolean controller and functions of applications to open the main VI.

  How can I control the Boolean LED in VI main, changing the State of the Boolean controller in an another VI?

  Thank you.

  There are different options, but depending on what you want to do. For this example I can't give you a specific solution.

  I do not understand why you do what you do. Why do you call your 'principle VI' dynamically? What is the advantage to do? There are also other ways to call a VI dynamically, based on real cases (for example the method "call and forget", etc...).

  In you principle VI, control you Boolean ("THATCHER") is not the case of corresponding event. This is not usually a good practice, keep it inside.

  Also, why you try to communicate with the caller and callee VI through such a way to twist? There are better ways to do it.

  In one of my projects, I use the user event to launch orders in case of case of appellant VI.

  some Associates more readings for you:

  http://www.notatamelion.com/2015/03/23/how-to-make-dynamic-subvis/

  http://forums.NI.com/T5/LabVIEW/Dr-Damien-s-development-event-structures-III-communicating-with/m-p/...

• URGENT::opening multiple files - i have 3 files in my directory... When I run the code I can open a file and read it... but the while loop get blocked after the first iteration... can someone me help or give some indications

  bbmChatDB of public database;

  public static FileConnection fconnRead = null;
  public static String fileReadData = "";
  public static InputStream is = null;
  data Byte [] = null;
  DataInputStream is = null;

  Here is my code...

  I have 3 files in my directory... When I run the code I can open a file and read it... but the while loop get blocked after the first iteration... can someone me help or give some indications

  try {}

  FileConnection fc = Connector.open("file:///store/home/user/documents/BSM/") (FileConnection); "

  If (fc.exists ()) {}

  Enumeration e = fc.list ();

  While (e.hasMoreElements ()) {}

  System.out.println ("files are:" + (String) e.nextElement ());

  play this file
  StringBuffer stringBuff = new StringBuffer();
  try {}
  System.out.println ("opening file")-;
  System.out.println ("file name is:" + (String) e.nextElement ());
  fconnRead = Connector.open("file:///store/home/user/documents/BSM/(String)e.nextElement(),Connector.READ_WRITE) (FileConnection);
  System.out.println ("data length")-;
  If (fconnRead.exists ()) {}
  is = fconnRead.openDataInputStream ();
  data = IOUtilities.streamToBytes (is);
  Ddd = new String string (data);
  fileReadData = ddd.toString ();
  System.out.println ("length of data:" + fileReadData.length ());
  System.out.println ("read data :" + fileReadData);

  }

  } catch (IOException ee) {}
  ee.printStackTrace ();
  System.out.println ("Exception in the read data :")
  + ee.getMessage ());
  }

  }
  }

  } catch (IOException e) {}

  e.printStackTrace ();
  }

  {Finally

  try {}
  If (is! = null) {}
  is. Close();
  }
  System.out.println ("is closed...");
  } catch (IOException e1) {}

  E1. PrintStackTrace();
  }

  If (fconnRead! = null) {}
  try {}
  fconnRead.close ();
  } catch (Exception e) {}
  System.out.println (try ());
  }

  }

  }

  You can recode this treatment so that it uses only:

  e.nextElement ())

  Once a loop iteration.

  Directly at the start saying something like:

  String fileName = e.nextElement ());

  and use fileName everywhere in your loop.

  Also be aware that printStackTrace() will do nothing in your situation, it only works if you catch Throwable.  So make sure you something output all your catches exception and also have a catch (Throwable t) to catch the things you miss, as follows:

  {} catch (Throwable t)

  t.printStackTrace ();

  System.out.println ("Eception exception:" + t.toString ());

  }

  I think your code is thrown an exception and you don't see it.