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Thang Nguyen

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Posts posted by Thang Nguyen

  1. QUOTE (sachsm @ Jul 1 2008, 06:36 AM)

    Can't you use Network Shared Variables for this application?

    To build the DSC I/O Server, first of all we have to build a custom VI then after that we publish all of the necessary controls and indicators to network shared variable and the communication between HMI and I/O Server through these shared variables. Currently I am working on the custom VI about the interface between this VI with HMI.

    Thanks.

  2. Hi,

    I am working on a custom periodic I/O DSC server. The article about building the Periodic I/O Server says that I cannot use the local variable, property node, or control reference for the controls or indicators I want to publish. But I have a simple case like this. I want to build a feature which handle the reset signal the device communicated with system by the I/O server. I use a boolean control as the interface to signal when the I/O Server send the reset command to the device. But after sending the signal, I need to clear the true value so it will not do it again in the next polling state. Without using local variable and property not, I don't know how I should do this.

    I still cannot thing another way, so I ask for help.

    Thank you for your time.

    Thang

  3. @Athony: You are right. My problem is, in the initialize ActiveX, I used a register event callback VI node. I tried to use the "initialize array" module to build an array of callback VI reference with only one callback VI reference. I have just tried to create seperate callback VIs and use the "build array" module to build the input reference for my callback register function. And it looks like the problem is solved.

    @Ton: your idea is really good. Even my first solution is wrong but when I use your methode, I can handle the hang situation.

    I also use the execution.state to track the sate of the VI. If it got hang the state will be "Bad". This is the first time I know how to use this property happy.gif.

    Thank you guys.

  4. @tcplomp: I am testing using your method. I also try with the property node return the state of the execute VI.

    QUOTE (bmoyer @ Jun 25 2008, 02:41 PM)

    Try using a sequence structure with 2 frames. Initialize in the first frame, and then put a Wait (ms) function in the 2nd frame to have the code wait for a certain amount of time after initializing.

    Bruce

    @Bruce: the PC will hang at the first frame. The 2nd frame has no chance to start.

    I am still testing it. Let you know when I got sth happy.gif

  5. Hi,

    I am working on a project which require to use an activeX module to communicate with another system. When I intialize the communication, sometime it got hang, sometime it's not. I try to use the delay module, but it didn't help. I would like to know how to implement a timeout module or watchdog so I can jumpout of the subVI.

    I intend to use this module (picture is attached) inside the subVI dealling with initialize the activeX module, but it stop the whole program. Do you have any suggestion?

    Thank you,

    Thang

  6. QUOTE (Yren @ Jun 19 2008, 09:20 AM)

    guys, i m doing speech recognition using labview for my final year project. Can anyone guide me on this ? thanks a lot and appreciate it much. :worship:

    You should at least start doing something before asking the question. I also feel interesting about your topic, but you should provide more information like Antonie questions.

  7. Hi,

    I have a situation which I need your recommendation. I have a main VI A which has a subpanel. I have 2 subVI B1 and B2. First of all, I load B1 into the subpanel of A. Now inside the B1 VI, I have a button which call for B2. What I want is when I click on this button, the VI A will load the B2 VI into the subpanel. There is also another button on this B2 VI to turn back to the B1 VI.

    My solution is I pass a reference of one trigger button on the main VI, and I try to generate the signal form the B1 VI to inform main VI close the B1 VI itself and load the B2 VI.

    I don't know if this solution is a right way to do or not. I am looking for a smatter solution. Currently I am still working on my solution. There is something wrong about the reference and I also get this error message: "The VI is not in a state compatible with this operation."

    So I hope you can help me.

    THank you so much,

    Thang Nguyen

  8. Hi,

    I want to ask a question.

    Is it true that the program will wait for 1 sec to get data for the first time reading the number of samples set by the rate? So in this case the whole system will be late by 1 sec. Is it true?

    Thank you

  9. I need to confirm that I understand right or wrong:

    If at the setting time DAQmx, I put Continuous Samples at the sample mode input,and set a constant rate x samples/sec, it means that the system will polling countinously with that rate into a buffer, and the data will be changed by the rate.

    Or when ever the program meet the DAQmx, it will wait for 1 sec to get enough data for the rate then return the data?

    But what is the relation between rate with samples per channel? If the buffer is full, will data be refilled from the start of the buffer. Where we can set the size of the buffer?

    Thank you,

    Thang Nguyen.

    In the second picture, I use a timeout for the queue to make the data acquisition run continuously.

  10. QUOTE(tcplomp @ Mar 1 2008, 12:44 AM)

    Hi Thang,

    Your timing is ultra critical.

    You wait one second to capture one second of data.

    If you remove the 'wait 1000 ms' primitive you wouldn't have problem. The Read function will force the wait for you.

    Good luck,

    Ton

    Ton,

    The rate = 200, does it mean 200 samples/sec? Actually I try not use the delay before, but I still get the error. So I am quite confuse about this setting time.

  11. Hi everybody,

    I need help for setting the rate for DAQmx. I have an application and I need to acquire data at 200 samples/sec. I did use the dynamic VI to do Data Acquisition which is seperate with the main VI. My problem is I don't know how to set the timing right. I try to set number of sample per channel to 200 and the rate in DAQmx Read to 200, but I received the error.

    Error -200279 occurred at DAQmx Read (Analog 1D Wfm NChan NSamp).vi:2

    Possible reason(s):

    Measurements: Attempted to read samples that are no longer available. The requested sample was previously available, but has since been overwritten.

    Increasing the buffer size, reading the data more frequently, or specifying a fixed number of samples to read instead of reading all available samples might correct the problem.

    I don't quite understand relation between the number of sample per channel with the rate.

    I attach here my screenshots.

    Thank you so much for your time reading this question.

    Thang Nguyen

  12. QUOTE(AnalogKid2DigitalMan @ Feb 8 2008, 02:42 PM)

    What type of load or device are you driving with the 200V PWM?

    Current requirements?

    I think these are really important information to consider. Making a circuit to drive a motor at 200V with a large current may cost you many MOSFETs for testing happy.gif. In this case you should use a heatsink with a dimension correspondent to the current.

  13. Hi everyone,

    I am working on a project which requires communicating with multiple similar devices. The communication with these devices is done through ActiveX, so I need multiple Callback VIs to process the tasks. But these Callback VIs have the same functions. Currently, I create the callback VI by right click on the VI Ref input of Reg Event Callback property node and select create Callback VI. I wonder if there is anyway more effective such as using multiple instants of only one VI (use reentrant). It likes we can put the Reg Event Callback property node in the For Loop and connect with an array of VI. I try to put the VI ref inside an array constant but I cannot do that. And event I can do that, I don't know how to identify these instants incase I need to debug them.

    Thank you for your time.

    Thang Nguyen

  14. QUOTE(gammalight @ Feb 5 2008, 10:54 AM)

    Hello,

    I hope my question is quick and painless to answer. I will add that I am new to using cRIO devices and FPGA programming. I have cRIO-9004 device that I am configuring in MAX. The 9004 is connected to the host computer via USB ethernet adapter and crossover cable. The IP address is 169.254.92.15 and the subnet mask ID is 255.255.0.0. When I start MAX the device shows up under "Remote Systems" with an IP adress of 0.0.0.0, which is a good thing. I then try to set my network settings, with an IP address of 169.254.0.2, which times out when I ping which means nothing is using this address already, and the same subnet mask ID, 255.255.0.0. I then type a name in the name field under the identification section. But when I hit the apply button I get a message that says:

    "The subnet mask you entered places the target and the gateway in two different subnets, which may make this partially unconfigurable."

    I can click okay, and it appears to let me proceed, but this doesn't seem right. Can anyone help me out, am I doing something wrong here?

    There is also a VISA error under the "Device and Interfaces" section.

    I am simply just fiddiling with the device, this is not for a project for school or a project for work, just for curiosity sake.

    If you use crossover cable, you should use the same 3 IP address fields which is 169.254.92.xxx in your case. Because you use 169.254.0.2, there is no way the host computer can communicate with the cRIO. That's what I think.

  15. Hi everybody,

    I would like to ask you for recommendation to build the DSC VI server in LabVIEW 8.5.

    I would like to make a VI Server which controls 6 similar devices. In each device I have multiple controls, indicators. I think about building the clusters which will group these variables together so I have only to build one time. After deploying the server, I will have only some of shared variables instead of thousand of separate shared variables. This is a big server which will control and monitor thousand of variables.

    The idea is I don't know if it will be convenient to control a signal or read a sensor's parameter or not.

    This is the reason why I want to ask for your recommendations before I try it myself.

    Thank you so much for your time.

    Thang Nguyen

  16. QUOTE(Darren @ Oct 15 2007, 02:13 PM)

    I'm trying to figure out why the breakpoint isn't being hit when the callback VI executes. In the meantime, I found a potential workaround (that requires access to scripting). You can put a BDWin.Open property in the callback VI to cause its diagram to open on the first call of the callback. On any subsequent calls, you can probe wires and the probes will return the wire values. This method won't work if you are only interested in debugging the first call of the callback VI.

    I'll post here when I find out more about why the breakpoint doesn't work.

    -D

    Could you please tell me where I can find the BDWin property node? I am currently working on the callback VI with ActiveX, and I have no clue how it works.

    Thank you so much,

    Thang Nguyen

  17. Hi,

    I am working on upgrading a project from DSC 7.0 to DSC 8.5. In the old project, I see they used the VI relating to the VI Server Development Toolkit which includes two sets of VIs. They are Server Registration VIs and Server Interface VIs. These are the old VIs. I think they were from 1997. Can anyone tell me if there is similar VI or what is the replace techique implemented for these VIs.

    If anyone has experience with developing the server, please tell me how should I do in the new LabVIEW 8.5.

    Thank you for your time reading and answersing my question.

    Thang Nguyen

  18. Hi,

    I 've just thought about building a GPS device which include of reading the current position data from GPS receiver modem connect through USB and loading the map data from a database using LabVIEW. I think maybe I can use this application on my car. I am trying to find document about this topic on internet but I cannot find out how to use a map data and how to load it. If anyone have experience working with GPS map before, please give me some instructions.

    I will add another features later, I just one to try some basic steps first happy.gif.

    Thank you so much.

    Thang Nguyen

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