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Need help with interfacing HC-SR04 Ultrasonic Range Sensor with NI SCB-68/PCI 6251

October 31, 2017, 3:11 am
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I am fairly new to LabVIEW and i need help with connecting and building a VI for the HC-SR04 range sensor. I have access to NI SCB 68 connector block along with PCI 6251 using LabVIEW 2014. The HC-SR04 will be used to measure the amplitude of vibration(displacement) of a spring-mass system.

 

I have come across this topic where they have used SensorDAQ Vernier to connect the HC-SR04 to.

https://forums.ni.com/t5/LabVIEW/help-in-the-programming-of-the-Hc-sr04-ultrasonic-sensor/td-p/1971669

 

Any help will be much appreciated!

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Help data logging in LVM file and table on front panel!!

October 31, 2017, 3:57 am
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Hello I need some help. 

I have data being displayed in forms of arrays. I want the data to be displayed in one table on my front panel. I tried using the table  V but didn't succeed in it.

I am also logging data into an LVM file and would like to add the channel names into the file. I have got suggestions to use the "Set dynamic data attributes" but when connecting it i got some errors that couldn't be solved by me.

 

can someone help me in this part. I am attaching the VI and an picture of the problem area.

 

The picture channel names shows what I am trying to achieve

 

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Simple Time Chart issue, not so "simple"

October 31, 2017, 4:12 am
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So i have a much more complex VI, that this is a part of.....and I cannot seem to pin-down what the issue is here.

 

I have a simple strip chart set-up to gather temperature data from a chamber probe.    All I'm wanting to do is have the x-axis display the time that the VI is started (start), and the system time of the last data point gathered (end).

 

However, as the VI is running, it appears to be "losing sync" (Lagging) with the system time.    I run the base program at 100ms, but only pull-in the Temperature data every 10s.   I put in a timer control (1s) to speed-up the testing process, but still cannot seem to put a finger on the issue here?

 

Any thoughts?   Probably something simple that I have just overlooked.

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NI USRP TX/RX VI inquiry

October 31, 2017, 5:37 am
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I was working on a SISO (Single-Input Single-Output) system. I ran the simulation version first and everything runs fine. Then i tried to implement it on USRP 2920. 

I found many examples of how to configure it but i wanted a detailed explanation of the working.

image.png

I am accessing this in a particular transmit state. I give it a data of one frame equivalent to 3000 Symbols and 30000 Samples (Upsampling factor=10). In total, i have to send 10 frames. So as soon as i write TX data of one frame would that be placed inside the USRP buffer and transmission would start for that with the sample or I/Q rate defined? What does timeout really mean in this context, is it defining the time/ultimatum given to USRP to transmit one frame of data? Also how can i cause a continuous stream of transmission. Since i think logically buffer 'may' become empty and we are still performing signal processing on the another frame (in other words we are not in the transmit state). Also why do we have to tell the USRP the end of data? Would this close the session completely or basically it would after transmitting the all the data in buffer turn off the carrier, etc.? 

 

image.png

 

Same confusion arises for Rx VI. Now if i define the number of samples to be equal to the total samples expected for the whole message, would the output of this VI be the whole vector containing all those symbols? Or when this is called whatever data is inside USRP buffer, it is given into the PC memory and that is the output. Also what is timeout in this context aswell? Is it telling the USRP to collect the amount of data in given time? 

 

 

 

 

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How to display accurate elapsed time on waveform chart/graph

October 31, 2017, 6:11 am
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Hi everyone,

I have one last problem for my measurment program.
I want to make the chart/graph or diagram or anything like that to visualise the values during the process.
I used waveform chart, but i dont know how to set the real time on the x-Axis. I tried with multiplier, but it didnt work well, because my multiplier is some decimal number as 0,871151.. and it is not very accurate after the period of time.
Do you have any ideas how to make it work? 

Thanks in advance!

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Is is Possible to count any particular address bit of Siemens PLC?

October 31, 2017, 6:42 am
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Dear All

i have project in which i monitor shared variables of Siemens PLC.

i stuck on to count memory address from PLC.

i want to count any particular address say "M0.5"  that how many time used in whole project.

is it possible to count that from labview and display count value as a integer on front panel of my labview project?

Please help

Thanks,

Asif 

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Error -200022 for cDAQ-9174 with Three NI-9237 Modules

October 31, 2017, 8:17 am
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I am trying to run a simple code to read three channels from each of the three modules. I am using the LabVIEW express VI as shown in the image below. VIHelp.PNG

When I run the code with the two task as shown in the image the code runs fine. As soon as I add a third task (using the express VI), I receive error-200022. This error switches from task to task each time I run the code. 

 

Is there a way to manually code around the Express VI to run 3 or 4 simultaneous tasks? 

 

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Error code -63195 for Invoke Method: FIFO.Write

October 31, 2017, 8:21 am
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Can someone tell me what the error code -63195 means in Labview 2017?  I get this when I use the Invoke Method: FIFO.Write from the RT to a FIFO on the FPGA.

 

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String Formating Date

October 31, 2017, 8:44 am
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Hello, this is most likely an easy thing to do but I am not great at formatting string data type.

 

What I am trying to do is take a time stamp (ex: 10/31/17) and format it to 10-31-17.

 

I am not sure have to change the "/" into "-" or remove it all together so the date is just 103117 that is fine too.

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labview oop question: MUST A child class implement all parent methods?

October 31, 2017, 9:26 am
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It is my understanding that when a child class is created from a parent class that the child MAY override the parent class methods (VIs) but it is NOT required to. And that if a child class does not have a VI that is in the parent, that at run time, the parent VI will be used (dynamic dispatch).  However, my LabVIEW code doesn't work (I know it's vague) when my child class does not have all the same VIs as the parent class. My parent class DOES have implementation code inside all of its VIs. I have many child classes of the parent and only one of them needs to implement different code for say a Stop VI. All other child classes are ok using the parent implementation of the Stop VI, so why should I have to create Stop VIs in all my child classes?  I have done some reading. In the LabVIEW help it mentions in various places an in various examples that the child class CAN override the parent methods. And there is even a parameter to force all children to override. However, I cannot find a statement anywhere that explicitly says that a child class MUST override ALL parent method VIs, or a statement that say that a child class DOESN'T HAVE TO override the parent method VIs.  I would think this would be default behavior but perhaps there is an obscure setting I'm missing? ( I didn't see anything applicable in the class properties dialog under inheritance.

 

Details on specific error (though I don't think related to my question):

The 'offending' omitted VI contains nothing but a DAQmx Stop Task and Clear Clear Task. Note that the parent Stop VI is indeed called, however, DAQmx Stop Task produces an error Error -200088, Task specified is invalid or does not exist. I create a child Stop VI with the exact same Stop Task and Clear Task, the child Stop VI is indeed called dynamically at run time but I do not get this error.

 

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waveform data start from zero using arduino interface

October 31, 2017, 9:21 am
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How can i start waveform plotting from Zero instead of time or date? I'm using arduino interface.

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[noob alert] Trying to filter signal in NXG 1.0

October 31, 2017, 9:47 am
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Hi,

 

I've been trying to filter a signal from a speed sensor (here) from a VI project I inherited from a coworker. I've seen tutorials on youtube and on this forum, but it seems my coworker set things up a bit differently so it's difficult for me to workaround that. The main difference I'm seeing is that I can find the raw data to filter (which I think is hidden in a .task?). Attached is a screenshow of what I'm working with.

I've tried to add a low bypass filter in the main and display_rpm images (where I helplessly ask "here?"). I got the error that I was above half the sampling frequency, which I think is because the DAQmx box (or whatever it is) is configured to only have the value spit out and not the signal. Attached is also the daq_mximage that shows my options. Does chaning one of these mitigate my issue and effectively help filter this signal?

 

thanks!

Kevin

 

 

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Browsing through tab control does not work while running

October 31, 2017, 9:56 am
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Hey folks,

 

my Labview Software has a TabControl which does not work anymore. 
I can click through the registers when the Software is not running, but I can't browse through it when the program is running.


I spent a lot of time trying to resolve this issue and in the end copied the whole thing into a new .vi that I uploaded.

Is anyone able to tell me why those registers can't be changed in running mode?

Thank you

Anna

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HD/SDI video capture device that is proven to work well with NI Vision

October 31, 2017, 11:24 am
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Can someone recommend some HD/SDI video capture devices that are PXIe, PCIe, or USB -- that has LabVIEW drivers/VIs available?  We have NI Vision Dev. But, we currently have to convert the HD/SDI to HDMI and then capture that on a StarTech USB3HDCAP and input to USB 3.0.

 

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What is SimDev1 used for?

October 31, 2017, 12:43 pm
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Hi,

 

I have came across the SimDev1 device name but never understood what the point of it is. I am currently waiting for my IO card to arrive, so I want to know if I somehow can use SimDev1 device to simulate the behavior of the inputs of my IO card? Thanks in advance.

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Changing Eddy Current Brake

October 31, 2017, 1:11 pm
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I have a Schewinn Journey 1 exercise bike.I'm trying to bypass the panel and change the resistance level directly with a labview program. I looked at the manual and it uses eddy current brake to control the resistance level and a servo motor ( and voltage between 9-12 volt). I'm wondering if this project doable? what type of DAQ should I buy? can you please give me advice

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Network Shared Variables not recognized after re-opening the project

October 31, 2017, 2:49 pm
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I have exactly the same problem as SoheylV and LeBobbyshoot from the last couple days.

 

LabVIEW RT 2017 f2 running on cRIO-9067.  Every time I open the project the same 5 of my 162 shared variables in saved in 2 of 4 lvlibs complain they are not in the project.  This application was migrated from an working system running LV 2014 and the problem occurred on this machine in LV 2014 also.

1. Using the Select Variable... menu the variable is visible but cannot be selected

2. Show Variable in Project is greyed out

3. Dragging the same variable from the project to the VI shows a broken variable (black)

4. Deleting the variable and recreating it in another lvlib and it is broken on the next open

5.Find Callers from the variable in the project shows all the same broken VIs as having the variable!!!

 

The problem is the same regardless of the cRIO being connected or the variables being deployed.  All the variables are hosted on the cRIO.  One variable is a simple array of Booleans.  Another computer shows the exact same results.  Attached is the software installed on the cRIO.

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CLD Practice review

October 31, 2017, 3:17 pm
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Hi everyone, 

 

I tuned in to the webinar on the CLD exam the other day and they recommended putting up the CLD practice exams I had done on the forums. I'm not sure if this is the one he was referring to, but here goes!

 

I just ran out of time on the boiler example, but finished the car wash example with ample time left over. Hopefully they work the same for those of you who download them. I've not transferred projects/VIs in this manner before, so I'm a little concerned there'll be conflicts/breaks.

 

Thank you for your time and patience.

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Generating 9 dc signals in the same time

October 31, 2017, 4:42 pm
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Hi,

I'm wondering if there is a lab equipment that can generate 9 dc analog signals in the same time, I have an embedded system that should receive 9 dc analog inputs with different values in the same time.

Thank you

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mmwave Transceiver system

October 31, 2017, 7:19 pm
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How to use NI mmwave Transceiver System to measure channel response?

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