Re: LabVIEW as an in-process COM-server
rberger wrote: > I would like to know if LabVIEW is an in-process COM server—an > ActiveX DLL—that implements the IDTExtensibility2 interface. I > am trying to add a COM add-in for a current Microsoft product. LabVIEW is not an in-process COM server. LabVIEW is started as a separate process either as development system or as runtime executable and the Active X interface is out of process to the other application invoking LabVIEW's Active X interface. LabVIEW is also not embeddable into other applications through Active X. Rolf Kalbermatter
Re: Beep in labview.
This may sound stupid, but do you have speakers connected to your PC? And if you have, did you make sure the Volume Control Panel is configured to not Mute the loudspeaker nor the waveform device? Rolf Kalbermatter
Re: How can I get an unsigned char string with nulls from a dll into LabVIEW 6i?
Well I would certainly go for the unsigned 8 bit array parameter method. That is the best one and contrary to your claim does not require any changes to the DLL. For the rest it is a good recommendation and the most direct approach to do, what the OP has to do. Rolf Kalbermatter
Re: Need Help: How to design USB Driver for USBN9603
Well, I don't see how you could get at the information necessary to talk with this device from the link you provide. Doesn't National Semiconductors have a Software Reference driver with SDK you can purchase for this device? You definitely need Software driver specific informations, such as the manufacturer and product ID, but also some more informations about the endpoints and possible stream formats. Yes it seems rather difficult to me. Not a single weekend project for sure. Rolf Kalbermatter
Re: VI loads slowly if VISA serial control is on the front panel
Measurement & Automation Explorer does not change the VISA Configuration from itself. It is meant that those settings are only changed when M&A is open and the user requires a rescan or removes or disables devices explicitedly. It is always tricky to do full autodetection and automatic configuration adaption without sometimes loosing carefully edited configuration items. As to the delay I have seen that too, but assumed that it was a standard VISA 3.0/LabVIEW 7.0 problem. It's interesting information that this may have to do with (default or stale) information in the visaconf.ini file to non existing resources. Rolf Kalbermatter
Re: Necessary to make strange tweaks to my array data pointers when
Well, watch out about adapt to type! It will pass the structures as they are used in LabVIEW. This can have a number of pitfalls. 1) LabVIEW uses it's own format for strings and arrays, called handles. It is a pointer to a pointer to an array with one int32 per dimension in front telling the size of each dimension. No other environments do use this type of format by default, although if you know it you can always account for it on the C/C++ or even Delphi side. But passing structures which contain strings or arrays by adapt to type will usually not work unless the DLL is specifically aware of the LabVIEW types. 2) Byte alignment can be an issue too. LabVIEW packs structures as much as possible on Windows. Windows 32bit API does nowadays often use long word alignment for longs, floats and doubles. Delphi might want to do that as well by default. Your Delphi documentation should be able to tell you such details (I would hope). You can adjust on the LabVIEW side for this if necessary by adding explicit dummy filler values into the cluster. Unless you have a flatten or typecast function in your wire the byte order should be always the same as the CPU on which it is running. The Flatten (and Unflatten) or Typecast function do always do a byte and word swap for according data types when you convert from or to larger sizes than 8 bit values. So when you do Typecast your int32 to a string or byte array the order of the bytes is reversed on the other side. Basically if you build a cluster in LabVIEW and Typecast it to a string to pass to a DLL, what you should do (only under Windows and Linux!!) to the Cluster wire before wiring it to the Typecast function is putting a Swap Byte and Swap Word function in the wire. This will take care of byteswapping any values in the cluster correctly to compensate for the byteswapping the Typecast will do. Of course since about LabVIEW 6.0 you can also alternatively select the CLN parameter to adapt to type and then you don't need to byteswap and typecast at all. But watch out: If the cluster is not flat (e.g. contains strings or arrays, you can see that the Typecast will refuse to connect properly to that wire as Typecast can only convert flat data types) you can't really pass such a cluster easily to a DLL nor by Flattening it nor by using Adapt to Type. When Flattened the enntire cluster will be put in one single buffer, with the strings embedded into it, which is definitely not what any DLL ever would expect. When using Adapt to Type, the embedded arrays (and strings are really byte arrays too) will not be passed to the DLL in a way which a DLL can understand by default. Last but not least, LabVIEWs Boolean is really a 8bit integer with the LSB indicating the state. WinAPI and probably Delphi too, use a 32 bit integer to represent Booleans. You can easily adjust for that by including a n int32 with value 0 or 1 on the LabVIEW side. Rolf Kalbermatter
Re: 7-segments like digital indicator
Well, not sure what you expect. I find that font reasonably well. But you could always create your own font using some freeware or shareware font editor. As long as you only need numerics you can get away with 11 to 13 font characters (0-9,.) Rolf Kalbermatter
Re: how to transfer 2d array between LV Call Lib Func Node and a DLL?
Depends what you understand under a 2D array. In C a two dimensional array will sometimes be a pointer to an array of pointers to the array of data. This is not how LabVIEW can pass 2D arrays. LabVIEW 2D arrays are really just a pointer to a single array with row * column elements. Rolf Kalbermatter
Re: call IMAQ DLL from c++
I think you will need to look into the IMAQ Vision for Measurement Studio package. Rolf Kalbermatter
Re: Question about slow rs232 equipment
A PIC for instance does not have a FIFO for its standard serial port module. You get a byte in a register and if you are not fast enough before the next byte is ready things might go wrong. Of course writing the PIC formware in such a way that it can always deal with the maximum input rate (for instance 9600 baud => ~1ms per byte) is the real art here. Also you can consider handshaking too, although the PIC module does not have this automatically. Rolf Kalbermatter
Re: Necessary to make strange tweaks to my array data pointers when calling dlls
>You pointed out that depending on which calling >convention you use, either the function or the calling >code pops parameters off the stack. Which convention >does which, and does one method inherently involve > less overhead than the other? With cdecl the caller is responsible to adjust the stack pointer whereas with stdcall the function itself adjusts the stack pointer. stdcall is supposed to be a tiny wee bit faster but I'm sure you won't be able to measure the few nanoseconds. I'm not exactly sure on what claims this is actually based, but have decided that worrying about this form of optimalization is simple bullshit as long as you don't program in assembly. What you explain with the byte order I'm not sure what you mean. It all seems wrong to me. Of course if you convert an int32 to a boolean array the first bit will be visually on the left side as arrays are typically interpreted in the same direction as we read text but that is only a visual representation. In memory an int32 consists in LabVIEW of 32 bits in the native format. So unless you tell us what Delphi type you try to create (and hopefully my rusty Pascal knowledge is good enough to understand it) I can not really tell you what you should rather do to get that type. Rolf Kalbermatter
Re: Win32 call--Possible to use a pointer to a pointer?
I guess when saying Code Interface Node above, you really mean the Call Library Node. Because if you had a CIN you had some C code to write and in there you could do whatever you wanted. As I have pointed out at other places here you could use a little LabVIEW voodoo to get at this information. Basically you would need to copy as many bytes as the buffer should contain from that pointer to a byte array. You can do that with a Call Library Node configured to call a documented LabVIEW manager function. Library: LabVIEW Function: MoveBlock Calling Convention: C decl Return value: void 1. Param: src, uInt32 by value 2. Param: dest, array of uInt8, initialized to length of the structure 3. Param: len, int32, length of the structure Rolf Kalbermatter
Re: Feature request and how-to info for EXE icons
This is not so bizarre. LabVIEW icons are internally really Macintosh resources and there is some translation necessary to get them into Windows format. Also by being able to convert the icon alone you are still not there. Putting them into the target executable is a little tricky at best. Rolf K
Re: TI PCI-2040
Programming hardware is NOT the task of an application, and LabVIEW is an application running in user space. Trying to do that right away will cause a General Protection Fault error on any reasonably modern OS. You can of course try to access Port IO addresses through the Port IO VIs, but PCI bus addresses are not anymore fixed and need access to privileged OS services to resolve properly. Otherwise if you start to use fixed addresses for this using Port IO access, it will most probably only work on a particular computer and may even fail next time you restart your computer or resume from standby with a different PCMCIA or whatever card inserted. These are all things only a device driver can do properly and so if you want to access hardware behind a PCI bridge, you really have to develop a device driver for this hardware to work under any Windows NT type, Linux or OS X system. The PCI bridge on the system board is not really programmed by you anyhow but by the OS which provides you with services to make use of the hardware. Fortunately developing a device driver only requires advanced C knowledge nowadays, it used to require also profound assembly language knowledge only a few years ago. Rolf K
Re: Feature request and how-to info for EXE icons
I took a look at this. The actual functions doing the icon work in the application builder seem to be called by reference from vi.lib\platform\icon.llb\Read Icons From ICO File.vi and Write Icons To Application.vi. One problem is that even though the read VI does read all types of icon formats, the write does only overwrite existing icon formats in the resource fork of the executable and that contains currently only those four images. So I would believe by adding the other resource types you would like to the applibs/lvapp.lib file (which really is an executable to startup the LabVIEW runtime engine and is used to create the actual exectuable file) you could get the Application Builder to replace those resources with the ones from your icon file. There is a problem though and it is not very simple. If your icon file does not contain certain icon types the old ones will stay in and might be picked up. Removing them or adding new icon types not in the original file requiures to resize the entire executable and fixup quite some offsets in the resource table for this. There are some Win API functions which are supposed to help with that, but I'm not really familiar with them. Rolf K
Re: i'm reading value from memory addresses one at a time. How can I store my values in an array?
The bad way: Using a shift register and a build array function node append them to the array. The good way: wiring the value to the loop boundary and enabling autoindexing. Autoindexing is enabled by default on a For Loop, but needs to be enabled on a While Loop. Rolf K
Re: How to update front panel immediately with any control change in LabVIEW7.0?
I solve this problem by combining the event structure with a classical state machine. The classical state machine is a case inside a loop with either an enum or string shift register defining the actual state. In the idle case of that structure is the actual event structure which handles the UI. Whenever I need to trigger a specific action which could happen from multiple locations I actually place the handling code in a specific case in the outside state machine and just wire from the actual event case the according state out to the shift register. This architecture allows for a very flexible and extende state machine programming with the event structure doing all the UI event handling and the state machine doing the more involved actions or series of actions. Rolf K
Re: How do I determine the number of plots on a waveform graph?
Usually by reading the graph terminal or a local of it and determining the first or second dimension (not sure which at the moment) size of the resulting 2 dimensional array. If it is a 1 dimensional array you have either only one plot or an array of clusters each representing one plot. But as these data types are determined by compile time, there shouldn't be a problem with this causing ambiguity. Rolf K
Re: CIN memory problem
out: > return err; free(RxData_tot); // free memory free(colore); // free memory free(scan); // free memory Your function never reaches the memory free functions as it returns before that with the err code. Removing that return altogether seems like a very good idea to me. By the way it is not a very good idea to return anything else than noErr from CINRun(). This will immediately abort the entire application. It would be better to just return the error in an extra error variable and deal with the error in traditional ways through error clusters for instance.
Re: Application Memory Full - how do I stop this?
Shift registers accumulating data with Build Array or Append String functions inside! Bad calculation of For loop count with autoindexing output on foor loop boundery. Or simply an autoindexing output on a while loop. The CPU may be slow but 32 MB is fast depleted in a loop when you create an array of double precision values. PS: You should have also a math coprocessor 387 installed or things get a little difficult in LabVIEW. Rolf K
Re: MOTION - S-curves
On another similar thread I saw a comment from NI support that there is currently no formula for the time-distance graph available for the S curve parameters. The advice was to use Motion assistent to look for these parameters in the according graph. Rolf K
