Valve on / off substitute in while loop

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• 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.

• Stop and start the task in while loop

  I try to start and stop an output meter (creates pulsed output) in a while loop and I don't know how this is possible. I have a while loop running who is taking measures from a digital compass. If my title is within acceptable limits, the outputs of the meter (2 of them to turn to the left and right) must be turned off. If the title is out of the acceptable range, let say too far to the right, I want to start one of my outings of the counter to activate the object to the left. The issue I am having is that if I put the block 'Start the task' in the while loop the system will try to start each iteration of the loop, even if it is already on. I don't know if there is a problem, but it does not appear effective from a programming perspective. I remember reading somewhere that stop and start tasks can really slow a loop. Any suggestions?

  I actually just to understand it. If you use some if statements and the "fact of task is" block you can make it work.

• 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.

• start stop multiple while loops

  I have a fairly large VI that works while several loops with the strutures case inside.

  I would like to be able to close and on all looped programmatically according to events. (complete cycle or cycle started)

  I need to store my data in a table, but whenever I turned off the while loop data I gathered is lost.

  It goes like this-measure analog voltage - put it in a digital indicator... now I want to put it in a table only once by my machine cycle.

  If the opeator push the reset button, the table is available for acquisition of report generation.

  Any help would be appreciated.

  Thank you

  It's here.

• Sharing of Boolean values across while loops

  I'm new to Labview and I try to use an angular encoder as a type of switch.

  I want to take measures continuously from the angle of the encoder and turn on an analog output signal, each time comes in a certain angle. When the encoder drops from this angle, I need the signal to turn off.

  To do this, I try to run two parallel while loops. We measure the angle of the encoder, while the latter creates the output signal. What I want to do is to put a logical statement in the measurement loop that will record 'true' if the maximum angle is reached. I try to get that 'real' statement in the loop of generation of signals as a trigger to turn on (using a case structure and the "DAQmx Start Task.vi") output. The question I have, is that the 'real' statement cannot exit the loop to measure up to the end of the loop. But since I'm running it continuously, the loop ends. Thank you.

  Create a local variable of the Boolean in anxiety.  Right-click on the local area and select change reading.  Put this inside the loop else local.  If you have a loop that writes to the Boolean value and a loop that reads from the local.  Now you can remove the wire that comes from a single loop and feeds on the other.  Then your curls will work in parallel (if there is no other dependencies of data between the two loops).

  As an alternative to local variables, you can use a queue to transfer data from one loop to the other.  A loop (the producer) will write to the queue.  The other loop (consumer) reads from the queue.  See the examples on the architecture of producer-consumer for more information.

• Write on the worksheet while loop problem

  Hello dear Labviewers. I have a 'writing on spreadsheet"with a table 2D DBL connected on it, but the problem occurs inside the while loop. I want exactly those time six values in my excel document, but it restarts after every "two seconds" and I cannot get rid of this problem. I want exactly the same numbers in the Excel document as it is in the table.

  I tried to move the two "write to the spreadsheet' boxes outside the while loop, but the Excel document does not display a single value in the table, when I do this. It shows that the two headers

  My second problem is rounded off on the numbers. Even if I wrote "%.6f" in the part of the format, it gives me a single decimal value.

  Thanks in advance

  Orlando

  

  Orlando says:

  Thanks for the help Ravensfan

  But the "worksheet to write" not a not an output port, then how can I do this?

  I downloaded my VI

  I never said anything about writing about a spreadsheet file with an output port.

  See the attached VI for changes.  It's only the new data of this iteration of the loop that will write it on the spreadsheet file VI, not made all of the table from all iterations.  There is an entry of table 1 d to the spreadsheet file.

• for loop in while loop

  To all,

  I have a question, I have a loop within a while loop. The loop runs and displays the log data. It seems that, until I have stop the while loop that log data display. It almost seems that the for loop runs until the while loop is stop.

  The following accessory is an example of what I have in my code. But the because the loop runs in this example. My code is the same idea, but the loop seems to run when I start my program with execution of climax. Otherwise, it runs once I left the while loop.

  All entries?

  Thank you

  Cosmica

  I tried your VI and there is nothing wrong the way in which it executes. Nothing happens until the second tab is selected and you press the 'off' button, date on which the loop FOR runs until the indicator shows a "9". In subsequent runs, again, it count up to nine, but it is so fast that you never see. For the observer, the indicator remains at nine.

  Of course you would see things a little bit better if you place the small waiting inside various parts of loops. At present, the VI consumes all CPU do nothing but turn empty loops for always while spending from time to time some nanosecods to iterate through the loop FOR. You also destroy your resource VISA with tunnels of default output, so the fence at the end probably will fail. Overall, the code seems too complicated for what you want to do. Do you really need to link a case control tab structure? Seems unnecessary. The for loop should run when the button is pressed, since this implies automatically that Your ' e on the second tab, you don't need to read the tab control. It's redundant!

• How to increase code efficiency in a while loop (using PXI5105 for sampling outside signal digitalizer)

  Theoretically, we want the PXI-5105 (digitizer) have 302 record with each record has a 1260 sample (the save operation is inside a while loop) in approximately 30ms, however we have found that for each period (30ms), the PXI5105 only perform about 10 records. It is so wired. I wonder if the operations inside the while loop consume more time (for example 3MS), so that he cannot have 302 records even the PXI-5105 have 60 M/s speed of sampling. Is it true, you can find my labview code and if possible can you give me some suggestion in the most short time of operation of the loop.

  

  Please find attached labview code.

  Hi g_l_g_s,

  The digitizer PXI-5105 acquires data at the speed that you specify and stores the data in its memory embedded (up to 512 MB). The data is then sent to your computer when the Multi Fetch Cluster.vi is called. In VI that you posted, you are only fetch record during each while the loop iteration. If you want to retrieve 302 records you will need to specify 302 files in the horizontal Timing.vi to configure. For more information about scanners, you might find the DevZone, hereuseful.

  To determine the amount of time it takes for each while the loop iteration, you can consider using the structure of code in the example comparison community calendar, which is located here.

• structure of the event + while loop

  Hello, I am trying to understand how to unite two while loops in attached VI for half a day

  The first loop creates a state machine solid which reacts on each key and runs one of the structure cases. (that part works very well)

  The second loop, always generates the random number, but it stops the generation during the time where one of the structure cases events are executed. (this is the part ticky)

  Any suggestions?

  If you want your random number to stop so that the user triggered events are running, you should be able to simplify your design a lot.

  It can be done with a loop using the case of timeout.

• Retaining the last value without a while loop

  Hello

  I'm using LabVIEW 2013. My VI is attached. I'll send in a 'Curr. Random random numbers TestPlan Row"time. I'm eager to keep his last number, whenever this VI is not called and then reset the value to its new value whenever the VI is called again and a new number has been sent. Also attached is a screenshot at the VI.

  Please note that I can't use a WHILE loop, so it must keep its value in a different way...

  Thanks in advance for any help!

  SM

  Maybe a feedback node?

• convert loop timed to normal while loop

  How convert a while loop time normal while loop with exact same properties and performance?

  I have donot need to worry about the exact date. But it takes the timed loop time will be run similar to loop.

  And also, is there any issue encountered when we use Timed loop? problems such as that crashing exe?

  Hello

  1 kHz is the used base clock. Then, you decide to use 10 as period (dt) which is 10 ms.

  The clock is selectable in real-time systems, you can use the 1 MHz clock, giving resolution µs

  But for your needs, using 1 kHz clock with dt = 10 and using a ms of waiting with 10 connected to it is exactly the same.

• Functions don't run when a loop running in a while loop

  Hi all

  I have a loop within a while loop. All main functions are running in this while loop. However, once the for loop executes other functions in the while loop don't work anymore until the loop for stop execution. Could someone help me with this problem? Thank you.

  Kind regards

  Nicky

  Hi Nicky,

  Ah, well I don't have much suggestions but maybe you can try with a conditional for the loop. I've attached an example. You can go through it. I don't know if it's a good idea to use this way, but again, if this can help, so I'm glad that.

  To create a condtional for loop, place a normal for loop on the block diagram, right-click and select terminal condtional.

  Kind regards

  Amine31

  (Give congratulations to good answers and Mark as a Solution If your problem is resolved)

• CPU utilization while loop

  Manual LabVIEW declare a while loop must always contain a "wait for ms" vi to unlock the task for this period.

  However, I thought that it the same fate if I use the same timeout ms for the timeout of a structure event inside the while loop

  and omit the "wait for ms" vi.

  Unfortunately the time-out of the structure of the event does not seem to unlock the task so that the façade reacts very inert in this case, even if it reacts
  prompt in either case.

  Does anyone have an explanation more in depth of this behavior?

  
  

• 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