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    LabVIEW 2009
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jcesar1029's Achievements


Newbie (1/14)



  1. Hello everybody, I was able to stop the VI during the interval scanning by creating an Event structure inside the producer loop with a time out of 500ms. Every 500ms it is checking if a scan happened. If a scan did happened, then it would go through a case structure where the data would get queue. So far the VI has been good. I will now implement an excel report in the consumer loop where the temperature values will be recorded with a timestamp. Thank you very much for this idea. Any suggestions on what I did are welcome.
  2. Update: So I eliminated the subVIs that were being used for Wait for Scan Complete and unnecessary code that were added to them. After doing this VI runs as before with the inability of interrupting the 15 minute interval. I placed the Stop button inside the while loop as someone suggested. It does stop the interval but returns an error as that shown below and an incorrect reading value of 9.91E+37 for a thermocouple. I feel that I am close to the solution (thanks to this thread) and will keep working on it. Edit: Here is a close up of the Producer loop. Hey bbean, I am going to try out this idea now. I will update you on the outcome. Thanks! Fluke_VI_Rev6.vi
  3. Hey Jordan, Here is the error I was talking about. Here is what I did, I took out the elements outside the subVI and tried to run it.
  4. Hi bbean, Thank you for your reply. Quick question before I try this, wouldn't this not work since the data flow will be in the Wait to Scan Complete while loop? If I press the Stop button, the event structure will not operate because I am stuck in the while loop. I would need to stop the while loop, prior to moving on to the event structure. Please correct me if I am wrong. The loop inside the Wait for Scan Complete iterates at different values: 232, 231, 234, 244 for an interval of 10 seconds. So for a 15 minute interval it would be around 21,960 iterations. I will try that again. I will reconstruct the subVI in the main VI and connect the stop button to it. I tried this yesterday, but I was getting an error (VI broken arrow) where it said it cannot run because the subVI Operation Status cannot run without being inside another VI. That is what I understood. I will upload the error shortly if it happens again. I will keep you posted.
  5. The instrument will read the card where the thermocouple are connected to. Yes, hardware converts the voltage value to a temperature value not LabVIEW. The LabVIEW program sends the initialization values to the hardware and sends the signal to start the scan. Then the VI will read the program through VISA read. The hardware is connected through Ethernet. Let me show you in depth of each subVI. Keep in mind these subVIs are part of the Fluke 2638 that NI offers. Here we start with the main VI. Inside Wait for Scan Complete subVI Now, inside Operation Status subVI; which consists of a CMD and Read subVI The CMD subVI is shown below; it has a Execute Single Command subVI Finally, the Execute Single Command subVi Let us go back to the Operation Status subVi, which has the Read subVI as shown below In terms of your idea with the timeout, I would like the hardware to do the counting of 15 minutes not the software. I am leaning towards modifying the subVI and constructing my own algorithm to read the buffer of the hardware.
  6. Jordan, I understand your idea and it is a good solution. The interval time with a few ms is not a big issue. The only concern I have, which is a personal preference, is I want to have the Fluke hardware to do the timing. Based on your experience, why would I not be able to change the subVI or make a copy of it? I am curious. The 15 minute scan cannot be split into shorter scans. The nature of the 15 min scan is to take thermocouple readings (15 minute is a standard time). During the interval, the hardware is counting time and once it reaches the 15 min, it will read the thermocouple(s) and update the scan count. The hardware is a Fluke 2638A Hydra Series III. The hardware has a Cancel Scan option that allows the user to manually abort the scan at any instance. I will try the global shared variable and also look into the message queue. What do you mean it should be handle by the main and not as a timeout? You are right, the goal is to take a datapoint every 15 min.
  7. Sorry I wasn't clear on my question. I would like the Stop button to stop at anytime the Wait for Scan Complete subVI which has a timeout value of 16.67 minutes. The timeout value allows the program to return an error if there was no hardware scan after 16.67 minutes (interrupts the VI). The Fluke 2638A hardware is set by the VI to an interval of 15 minutes to take a reading. Every 15 minutes there is a temperature scan. The subVI Wait for Scan Complete has a while loop where it keeps running until a hardware scan happens or the timeout is exceeded as shown below. When I press the Stop value, I cannot stop the program (obviously) because the data-flow is currently in the while loop. I am unsure as to how to stop this while loop which is inside a subVI. Hey Jordan, The large timeout value of 16.67 minutes (1000000 ms) is to allow the hardware to have an interval of 15 minutes. This means that the Fluke hardware counts down 15 minutes and takes a reading. Once the reading is taken, the scan subVI will return the value and move the data-flow to the next step. If the timeout value of 16.67 minutes was reduced to 1 second, we will not be able to take a reading every 15 minutes because in 1 second there will be no scan value detected. I think you are right, I need to approach this VI in a different way. The Front Panel of the VI with the input parameters are shown below. Please ignore the x-axis of the graph, I am still trying to get the timing correct.
  8. In your top loop you can place an event structure with a timeout value of the 15 minutes and place the scan code in the timeout event case with a reasonable (short) timeout input. Then in your other event cases you can process things like your stop button. Thank you for your response. I am confused on the logic. The event structure will have a timeout value of 15 minutes which will operate the case Timeout. In this Timeout case, the scan code will run once the 15 minutes of no events have occurred. It doesn't seem ideal because I need the scan to start as soon as the user starts the program. Also, what do you mean by connecting a short timeout input aside from the 15 minute timeout? Isn't there only one timeout input for the event structure which it would be 15 minutes? Please let me know if I am thinking it wrong.
  9. Hello everybody, I am trying to create a DAQ VI for Fluke 2638A that measures temperature every 15 minutes. I created a producer/consumer architecture for this VI. During the 15 minute interval (900s), how can I have the Stop button end the program? I need interrupt the Wait for Scan Complete subVI since this is where it stays during the interval of 15 minutes. I am thinking of adding a shared variable node where the subVI is able to read the value but I am unsure of this approach. Please let me know if there are better ways to do this VI or any comments that I can learn from. Thank you. Fluke_VI_Rev2.vi
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