menghuihantang

QUOTE (Mark Yedinak @ Mar 5 2009, 11:08 AM) What do you mean by 'style'? Is this what they called that you have to follow NI's favorites other than your own style?

First of all, what's the difference between CLD and CLA other than that CLA is much more challenging? Both CLD and CLA are graded by someone. For CLD, it's like you still got a standard solution to help for grading. What about CLA? It's an essay type of test, like the type of philosophy test back in college? The best part is who grades CLA test? :worship:

QUOTE (Adam Kemp @ Feb 25 2009, 03:48 PM) Exampel benchmarks in my mind would be those large-scale functions, like imaging functions. They require more resources from computer and running time is longer. If NI could improve their performances or shorten the running time while doing a better job, I would not hesitate to upgrade. Another big attraction is new staff, like voice recognition or computer teaching, just for example. I mean they are still challeging techs now. New staff that are useful for automation is definitely a push for upgrade, as well as improvements on current algorithms.

Just wondering which one(s) is the right course before the real test? Basic I & II and some practice =====> CLAD Intermediate I&II and experience =====> CLD or Advaced course and experience =====> CLD

QUOTE (Aristos Queue @ Feb 15 2009, 02:34 AM) 32-bit length followed by Unicode sequence, similar to Labview string.

A VB function which requires calling a string input by value: function exec_init(ByVal FileName: String): Byte In labview, I wired a string constant and made it a C string pointer. But it doesn't work. I tried to understant why. By converted to a C string pointer, a null-terminator is added to the end of the labview string; but a VB string doesn't need a null-terminator and causes the misinterpretation of the original labview string. Is this correct? If so, how can I pass a labview string to a VB program that awaits pass-by-value. Pascal string pointer is definitely not the choice, since it uses 8-bit for length info.

QUOTE (rolfk @ Feb 13 2009, 01:30 PM) NO offense, Rolf, but that is a little confusing. You are saying LabVIEW does one more step of processing before passing data into the Node? For instance, how do you pass a string by value in LabVIEW? In the configuration window, if a string type of input is chosen, only pointers available for string type. Now how LabVIEW converts this pointer string into a value string?

QUOTE (normandinf @ Feb 12 2009, 10:04 PM) In Labview, a control of integer is a value of the integer itself or a reference to a memory location? I thought in Labview, everything is reference, because it needs to be referenced on both front panel and block diagram. It cannot be two copies of the same integer for front panel and block diagrem, right? I did not find an answer on ni.com to this. So how labview represents its data type? I know for an image, it's always a reference to memory;but what about other primitive types, like integer, double and boolean?

Thanks much, everybody. I tried a few times again after reading through you guys' comments. It's not done yet, but at least I got somewhere. Labview doesn't crash now after I changed to "Pass by pointer", and I got a return value '205' which according to the DLL documentation is a DLL problem. Anyway, one problem solved. But it raised another question. I don't know VB, but How do you tell whether should use passbyvalue or passbyreference given a prototype of VB function, like this one, "function DESKWINReset(var ComPort, TC, Mode: Integer): byte". It says nothing that those three integers inputs are pointers.

QUOTE (normandinf @ Feb 11 2009, 03:24 PM) Thanks much. I changed to 8-bit unsigned, but labview still crashed every time. That's why I think it is due to type mismatch which causes memory leak or something in the first place. I attached an image of the VI, it's a simle DLL call. The dll function is relatively simple too, 3 interger inputs and returns a byte. function DeskWinReset (var Comport, TimeConstant, Mode: integer): byte; I have no clue what's wrong now. The dll file is corrupt itself??

A DLL, its return is BYTE type. tried to use the dll from labview, but the return type is either numeric or string. So how to deal with this VB BYTE in Labview? Here is the prototype of the VB function: function DESKWINRESET(var ComPort, TC, Mode: Integer): Byte

QUOTE (alukindo @ Sep 11 2008, 09:12 PM) Thanks much, Anthony. That Non Elastic Behavior is interesting and explains all the puzzles I have about database size staff. About the first question, it's about the the automatic generated .ldb file when you open a database. I think it's about access security. But I don't understand why at times you still can open it, other times cannot at all, and other times only one user can access it exclusively. I don't set up any database in anyway, therefore it doesn't make sense they behave differently. I am sure it's something easy, but I just haven't touched it yet.

I am using Labview database tools to access my database. Two questions puzzle me One is abou the database lock. It seems every time a connection to the database, it changes to lock mode. Sometimes you still can open it, other times you cannot. I am wondering how this database lock can be controlled. The other question is about the size. In the database, it requires deleting certain even all the tables at times. But I noticed that the size of the database kept increasing. Even it appeared to be empty, its size still larger than before. Does the deleting only make the tables invisible or what? Why the size keeps going up? They might not be directly related to Labview, but hopefully someone can help me with the puzzles. Thanks much.

QUOTE (millatime @ Aug 25 2008, 11:43 AM) go to http://www.ni.com' target="_blank">www.ni.com, search USB camera, and you will find the solution for your application. NI actually makes it simple for you now, if not perfect.

QUOTE (shoneill @ Aug 22 2008, 07:52 AM) Knows Issues No. 1 says using one webcam at a single time. I did. Every time I chose a different webcam, I turned off the program and re-run it. Does this mean I can only use one webcam at all?

I have two webcams, different models on one computer. Trying to switch between the two to see different directions. Labview detects both cameras, listed the names and fed it to the camera open vi, you can see it in the attachment. But the problem is, it seems the camera names don't matter at all, no matter which webcam I chose, Labview always uses the one whose name is alphabetically ahead of the other. Anyone has an idea what I did wrong?

QUOTE (rolfk @ Jun 18 2008, 03:56 AM) Thanks, guys. Jason's solution led me to dig in another big topic. I found out that LabVIEW actually has all structure templates ready for use (yeah, I just found out today). Cool.

I am trying to finish a VI which can listen to a TCP/IP connection and also be able to respond to user action at the same time. I put them in one while loop and keep checking each instance, like anything from TCP/IP and does user do anything on the front panel. But the result is the VI is not working at all. When it goes to listen TCP/IP, it stops and waits for data. I wonder if there is an event-driven listening for TCP/IP so that the VI doesn't need to stuck there for incoming data. Or other structure to implement what I want: both monitoring the TCP/IP and responding to user action? Thanks.

QUOTE (Thang Nguyen @ Jun 11 2008, 01:56 PM) I know where the confusion is. I tried this too, the problem is in the source code (VB), whenever this event is triggered, it returns the result directly; however in Labview, because of no pass-by-reference stuff and data-flow, it seems not likely to retrieve the returned data. The answer seems to be not possible.

QUOTE (jgcode @ Jun 11 2008, 12:09 PM) Thanks. But... that's how those VIs come from. The problem is once the event is triggered, the event data out is supposed to be modified and returned. But I only got empty string. Something is wrong or missing, unfortunately I have no idea.

QUOTE (ned @ Jun 11 2008, 11:41 AM) Actually the data returned is in Event Data out. User parameter is optional, I did try wiring something to it. It doesn't work. I didn't get anything except empty string from the event.

Here is the problem. I have a DLL written in VB. A couples of events are available, such as Public event DataStreamSample (Sample As String) once this event is triggered, it returns sample derectly in which current state information is stored. But in Labview, I cannot get this returned sample directly. The following pic contains the code. Anyone has the idea how to retrieve the returned sample? I checked and am positive that the event is triggered properly. But Event data out is still empty.

QUOTE(rolfk @ Dec 10 2007, 01:16 PM) Ok, found the name. It's Relf, who has a book on imaging stuffs. Well, a book can be a collection of articles, a working progress I guess :thumbup:

Thanks, Rolf, for taking the time to write that much for a rookie :thumbup: If I am right, I think I read a book authored by the same name. I just couldn't find the book in the shelf. Are you that author?

I am recently learning how to use those useful dlls coming with Windows. But the header part of the dll file is all confusing to me :headbang: , like this one: uint32_t SystemParametersInfoW(int32_t uAction, int32_t uparam, CStr lpvParam, int32_t fuWinIni); which is one method in user32.dll. Cannot even understand what those parameters are supposed to mean. Anywhere I can search or figure out how to use these dlls? Appreciate it. :worship: