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I never seen virtual COM ports on a single hardware COM port. I've seen them on A/D cards that control multiple devices, but not through a real COM port.
I don't think you can do this. Since you can only attach one piece of hardware to a serial port at any one time, what's the point of this? You'd have to attach multiple devices through some kind of multiplexor. This device would have to be able to communicate with a custom serial port driver on the hardware COM port so that the correct signals would go to the correct device and the correct replies would be sent to the appropriate applications.
Why would you want to do this?
Dave Kreskowiak
Microsoft MVP - Visual Basic
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thanks
i have to attatch multiple access lock controlls on my serial port which open the door after validatin that visitor from data base ,, this access controler got a function which sents the rfid card's serial number on com port ,,, but since there are multiple doors and multiple acces lock devices(each device for one door) and we have to use multi threading to read and respond from all of those devices at the same time .,,
is there any way ,
hello
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You'd normally use a multi-port serial card for this. I've seen them with as many as 16 ports on them. I hope all your doors are within range of a serial ports transmission limits. It's not like you're running over Ethernet or anything. IIRC, you've got to keep the two devices within, at most, 200 line-feet of the PC. Maybe more, maybe less, depending on the power output of the serial ports and the quality of cabling your using.
You'd be better off using something that's Ethernet based for many reasons, not the least of which is expandability.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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Dave Kreskowiak wrote: IIRC, you've got to keep the two devices within, at most, 200 line-feet of the PC. Maybe more, maybe less, depending on the power output of the serial ports and the quality of cabling your using.
With low baudrates and very high quality cables you can get a few thousand feet even in industrial locations with severe electric noise problems. IIRC you need to use optical isolators and powered signal boosters to do that though.
--
Rules of thumb should not be taken for the whole hand.
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It's been so long since I've done any serial port work, I can hardly remember anything! 
Dave Kreskowiak
Microsoft MVP - Visual Basic
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i have an application which takes a scanned image from a scanneer but this application stores this image in a size in which the scanner is configured ,, what if i want to crob (Resize)this image through my application before storing the image ? any idea ?
thanks in advance
hello
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How this is done depends on the library that you're using to get the image from the scanner. In an appication that's used around here, the previewed image is displayed, then the user is required to draw a box around the document before the final scan is made.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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how to send mails to the persons present in a table on a particular time...
i guess it is possible through Windows Service, but how???
can u please help me???
NaveeN
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Hi,
I'm interested in tracing .NET apps.
For a given assembly, that means I want to get a log containing all method calls/returns with parameter and return values, and exceptions.
I know about some tools like SpeedTrace.
My questions are:
1. are there any other tools?
2. can the Visual Studio Team profiler do this?
3. how would this be implemented, (using the profiler api? what about other ways?)
Thanks!
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AFAIK, there is nothing that will log all calls made in your application, logging all the parameters and return values. You'll have to instrument your code on the functions you want yourself. Come to think of it, there are so many calls going on in your code and in the framework itself that it would probably slow down your app to about 1/10th of it's normal running speed if this were done.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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Thanks for the reply!
Well there is the possibility of a .NET CLR profiler (many exist) that use the ICorProfiler (or whatever) interfaces.
They CAN log all calls etc. etc., and supposedly they don't slow the application down THAT much.
But:
1. They are expensive.
2. It's not easy to write one, because of the nature of the Interfaces (I don't like COM).
As for the performance issues, in my opinion most of the calls in a Windows Forms application are not interesting - I don't really care about constructors/destructors/event handlers/etc of GUI objects. I just want to log MY methods. So that wouldn't slow down too much, especially if the logging code does the minimum required.
So my question was, does such a tool exist.
(I'm asking this because I'm interested in writing one.)
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Not that I know of.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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I have a strange little problem with a bound datgridview. The DGV is on an unbound form but is itself bound to a bindingsource which is in turn bound to a bindinglist(of T) which encapsulates a list of business objects (with me so far.) Ok so when the user clicks an empty row in the DGV the addingnew event is fired immediately - kind of odd behaviour that I thought. The user then types some text into the new rows first field. When I check the contents of the bindinglist a new object has indeed been added but does not contain the text that was typed; in short it is completely blank. If you then reload the form move to the blank row added previously and enter the text again then the empty object in the binding list is correctly updated.
I hope you have all been able to follow this explanation and I hope even more that someone can explain what is going on.
http://www.ViSYNERGY.com
End of Line.
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Actually I have now solved this - at about two in the morning, I worked it out.
Calling endedit on the bindingsource component doesn't (for reasons best known to MS,) pass through to the DGV that's bound to it. So to make my code work correctly I have to call endEdit on the DGV first and then call endEdit on the bindingsource. I call this very strange behaviour, but at least now I can move on.
http://www.ViSYNERGY.com
End of Line.
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hi all
can any body tell me how to play flash files in c# applications
i have shockwave object but i dont know how to give it a path of the flahs file because there is no property like that
thanks
hello
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i've never tried doing this, but i would probably try putting a browser control on the fom and loading the falsh in that.
HTH
Russ
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When I launch application from IDE or from debug folder, it works well, I mean ThreadAbortException is processed as expected. But when I run the the same application from Release folder, it doesn't catch this exception and always throws an unhandled exception ThreadAbortException. How can I get rid of this bothering problem? Thank's in advance.
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You need to find the code where the exception happens and catch it there.
WM.
What about weapons of mass-construction?
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You cannot catch a ThreadAbortException. While your catch{}-Block is executed, ThreadAbortExceptions just re-throw themselves after the catch block. If you Abort a thread, it's really going to terminate. Don't use Thread.Abort to send signals to other threads, you can never know where the thread was when it is aborted and might leave your application in an inconsistent state.
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hi all
i have created a dll ,, and there is a function in this dll name (somehitng)
i have put this dll in an other prject,s root and every thing goes ok after creating a reference to this dll ..But problem is that when i debug this project the controll moves to that function (something) in that dll and all the code is seen clearly and i dont want that ,,,
purpose is that i dont want any other can see my code in that dll,, how to do that please tell me
thanks in advance
hello
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Try using doing a release build for the DLL project you created and use that DLL in the Release folder of ur DLL project in other projects this will avoid ur issue.
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Problem ois still
i have created a release built for my dll project and in my other oroject(test) i copied dll from release folder and put it in the debug folder of my other project (test)
but during debuggin when i press f11 the controll moves to my class in that dll and i can see my code clearly it is so funny , why ?
where am i wrong
please help me
hello
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Hi,
Just to make sure, Have you added the class library project in the project which you are coding on right now ? If yes please remove that project (Dll project from new one)
"A good programmer is someone who looks both ways before crossing a one-way street." -- Doug Linder
coolestCoder
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no its not there
but when i delete this dll project from my PC than the problem is resolved
but i dont think i am right ,, i must be wrong some where can u plz tell me
thanks in advace
hello
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