SerialPort DataReceived Buffer Construction?
Jun 15, 2011
I've managed to make an application at home using a serialport emulator and connector that will read text from a file on my desktop send it to com1 and then my connector program will merge com1 with com2. In short my program works at home but when I connect it to my device it appears the data in DataReceived is a fraction of what my simulator setup at home is producing, which apparently is completely normal according to all these threads I've read here.
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Jul 21, 2009
Im using VB express 2008 (compiled with .NET 3.5) to write a program that communicates with a USB device. The USB device is a communication class device and thus will emulate the usual rs232 serial port once attached to the PC. The USB device sends a fixed number of bytes and i have set the threshold received byte property to this value. I have run the program and it seems to read the USB device "correctly" but when i debug the code, i realise that the datareceived event of the serial port gets fired on the eventtype = EOF. I am using the Read function to read the bytes from the serial port and the Newline property is set to "" (but i thought that this is irrelevant if im not using ReadLine). When the datareceived event fires with EOF, the Read function blocks until one byte arrives, reads it and calls the function that processes the data. I went through the forum and realised that the EOF eventtype is no longer supported, is this true? I dont think that getting this eventtype is logical anyways in my case.
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Apr 2, 2009
When I write a byte array to a device using this code, the DataReceived Event never fires.....
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AND if the sleep is <40, the event doesn't fire. Is this necessary or am I overlooking something?
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Dec 29, 2010
Every 5 to 10 seconds I receive 5-12 bytes of data (confirmed w/Hyperterminal). I can open the com port(btn1), read bytes(btn3) until bytes to read = 0, but then i'm stuck; the data received event doesn't seem to respond. If I close the serial port(btn2), re-open i can read more data until bytes to read = 0 then stuck again. I tried several suggestions for threads and delegate and invoke but none worked. (WIndows XP, VB 2008)
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Jul 8, 2011
I have an application with serial port datareceived event. My instrument sends me aprox.00bytes every 1 second. Which I then process and update few textboxes on the main formRecently my application started crashing if I press close button.I am guessing form_closing closes serialport at the same time datareceived event triggers in which the sp1.bytestoread causes the crash.1. I added synclock in datareceived and in form_closing.Within synclock in form_closing I removed datareceived handler.
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Dec 16, 2010
So I just spent the last 4 hours trying to find out what was wrong with my code, just to find out that there's a bug in this version or I just don't have enough knowledge of VB2010 (I'm coming from VB6, this is my first program on 2010)I removed the rest of the code just to point out the problem, here it simply tries to enable the Timer1 when you receive data in the SerialPort1
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
If Me.Timer1.Enabled = False Then
[code]....
After this I found that the code inside the Timer1 didn't run when the 100miliseconds passed, so I added a msgbox to see debug.
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
If Me.Timer1.Enabled = False Then
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Dec 15, 2011
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This is my code for retrieving pictures, it was working before but then i accidentally deleted the table and i created it again with the same name and same fields. and now whenever i open the form with the picture, there was a message box error. it says Buffer cannot be null. Parameter name: buffer I don't know what i did wrong.
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Sep 10, 2009
I was perhaps too quick to think that VB's built-in event would be be easy to use. As you can see from my previous post I am building a program which sends and receives a few bytes from serial bus. The bus is actually a usb serial adapter, there are no real serial buses in my machine.Anyway that SerialPort1.DataReceived does not fire. It is from visual studio/vb ide so syntax should work? Here is my start up code. There are many comments, because I tried various combinations.
If Not _serialPort.IsOpen Then
If Not arvo = "" Then
_serialPort.DtrEnable = False
_serialPort.Parity = Parity.None
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Mar 15, 2010
i'm working with different classes and different constructors. It's working fine until i try to inherit a class that also has a constructor. vb asks for mybase.new but when i add that vb says that a constructor cannot call itself, when i try it in a different way vb asks the parameters of the constructor of the class that i want to inherit.
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Dec 3, 2009
I'm looking for a reference that can explain the concept and use of the DataReceived event and Delegates subject.The reference has to be pretty simple as I'm an "old dog attempting to learn a new trick". I'm not ignorant of things programming, but am ignorant of things dealing with serial communication in VB2005.I already have a couple of O'Rielly books ("VB2005 Cookbook", "VB2005 Desktop Reference") and I have a book that deals with serial communication from a Jan Axle-something. Neither O'Rielly books have any info, and the Axle-someting book's remotely related examples are too confusing for this slow learner.
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Jan 18, 2010
I have an Object(Class) that consists of a few List Of(T)'s where T is other classes that can be defined by reading lines of a CSV file.I could (I imagine) do the same thing with XML.My question is when does one choose between the two.Are there cases where one is preferred over the other for data storage?
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May 12, 2011
I must say personally, the WithEvents system is, shall we say, open to extreme false sense of security, so to speak. I like a lot of automation in my code, and tend to provide ways to do things manually, with a "default" behavior encoded. However, as I have just discovered, the withevents doesn't HOOK the event delegate until after creation. So even when you do New MyObject(), if an event is triggered during the Sub New() process, the delegate hasn't been assigned yet, and thus the event (which in my current situation is extremely important) never triggers. which begs the question the point of the WithEvents other than removing "AddHandler" lines from procedural code. Sure it saves on typing, due to code completion, but if that's it, that isn't much of a benefit. One would think that using the WithEvents would allow me to do:
PUblic Sub New()
MyBase.New()
RaiseEvent MyEvent()
End Sub
Tragically, this does NOT work, which royally screws up my lazy loading techniques and other such tricks that were supposed to make my code simpler to use, and instead has made things 10 times more complex, as I have to specifically alter class initialization sequences to be outside of class instantiation. (which should be one in the same, imho).Jaeden "Sifo Dyas" al'Raec Ruiner
"Never Trust a computer. Your brain is smarter than any micro-chip."
PS - Don't mark answers on other people's questions. There are such things as Vacations and Holidays which may reduce timely activity, and until the person asking the question can test your answer, it is not correct just because you think it is. Marking it correct for them often stops other people from even reading the question and possibly providing the real "correct" answer.
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Jun 29, 2011
I am trying to get a fairly simple Serial Port program working. So simple in fact I have been bashing my head over it for quite a while.
I have a piece of equipment connected over a null modem cable. When turned on, it just starts spitting data out RS232 and I need to capture it. Hyperterminal does see the data so the USB-serial converter is working.
When I run the code snippet included, the port opens fine, but the DataReceived event never fires.
Imports System.IO
Public Class Form1
Dim WithEvents serialPort As New IO.Ports.SerialPort
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Jan 3, 2011
I desperately need someones help on this one, as I'm completely stumped where this error comes from.
System.InvalidOperationException was unhandled Message="An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'" Source="Training Database"
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Jan 29, 2009
I need to iterate through controls using dynamic construction of control names and it looks like this could be what I need, however I never used this before and it does not quite work. What am I doing wrong? GroupBox1 is what I am attempting
Dim x as Integer = 1 For Each ctrl As Control In CallByName(Me, "GroupBox" & CStr(x), CallType.Method).Controls The runtime error is "GroupBox1" not found on Form1 even though I can select Me.GroupBox1 from the dropdown list.
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Apr 29, 2009
I'm in the process of developing a construction estimating program with vb 2008. Most of the programming I'm able to work myself through, but the problem and question that I have is I would like to incorporate a part of the program where I can import pdf, jpegs, tiffs of blueprints and have the ability to then set the scale, take area and length calculations, and basically do quantity takeoffs.
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Oct 27, 2009
How you might construct an array like the following: one column or entry would be a single integer, like 0, 1, 2, 3, 4... - i need this as an index of each one's position in the list the second would be 0 or 1, or true or false the third would itself be a list of integers 0,4,5,2,7,2,5,2...
So all together one entry would be {0; 0; 0,4,5,2,7,2,5,2} while the next might be {1; 0; 6,8,2,5,2,3}
I'm having a terrible time wrapping my head around this. It's mostly the third column which is actually a list in itself, that is giving me trouble
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Apr 14, 2010
I have two forms. A main form and then another form that you can change settings in. Now when I click on the menu item to get to the settings form I get this error. "An error occurred creating the form. See Exception.InnerException for details. The error is: The form referred to itself during construction from a default instance, which led to infinite recursion. Within the Form's constructor refer to the form using 'Me.'"I've tried these codes.
frmSettings.Show()
Application.Run(frmSettings)
those didn't work so i tried these
dim settings as new form = frmSettings
settings.show()
dim settings as form
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and those didn't work. I'm using visual studio 2010 Pro.
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Apr 17, 2010
To Double Buffer or not to Double Buffer this is the Question!I have a form with Protected Overrides Sub OnPaint that sets forms background to a gradient fill ,on top of that is a transparent richtext box.
Ok. now here`s the problem ,If i enable forms double buffering the transparent Rtb doesn't flicker when forms resized. but the forms drop shadow does flicker! ,its a boarderless form using CS_DROPSHADOW to draw the drop shadow Now if i disable double buffering the forms drop shadow doesn`t flicker but the transparent Rtb does ,any one have a clue how to get both to work in harmony !
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Sep 16, 2009
The reply buffer is in ASCII value...but I need is HEX value.Is there any way that the reply buffer is in hex?
Code:
Public Function read_write_string(ByVal devicehandle, ByVal command, ByVal commandlenght) As String
Dim inputReportBuffer(100) As Byte
unManagedBuffer = Marshal.AllocHGlobal(inputReportBuffer.Length)
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Apr 21, 2010
I have a problem that i cant solve i am trying to buffer 28 bytes from the com port into the array actual_packet_VPS1(30). It works with the counter set to 0 - 15 but doesnt work when we increase the counter size to 0 -28.
Private Sub MSComm5_OnComm(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MSComm5.OnComm
Dim buffer As Object
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Jan 12, 2012
I have a need to double buffer a flowlayoutpanel. I have the form set to doublebuffered which is half the story but their is no property in the list to make the flowlayoutpanel do this (although MSDN states that it has this property) how i can set it to true for the panel?
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Apr 29, 2012
Im trying to do a video player but i have to play this video from the buffer, is this possible.. Let me explain you much more complicated,a got a CryptoStream and im decryting the video
While lngBytesProcessed < lngFileLength
'Read file with the input filestream.
intBytesInCurrentBlock = fsInput.Read(bytBuffer, 0, 4096)
'Write output file with the cryptostream.
[code]....
This code writes my decryted or crypted video to a new file. However, i need to play the video file from the buffer(without copying to a new file), in other way it would be meaningless if i create a decryted file. in other words it would unsecure for me cuz if anyone can locate my temp directorey they can copy my decrypted video files.
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Jul 9, 2011
Dim Fs as FileSystemObject
Dim TS as TextStream
Set Fs = CreateObject("Scripting.FileSystemObject")
Set Ts = fs.OpenTextFile(textFilePath, ForReading, False,
TristateUseDefault)
While not Ts.AtEndOfStream
Buffer=Ts.ReadLine
' Process the buffer
Wend
Ts.Close
Fs.Close
I tried to convert into c# but am getting ERROR like EOF expected, what I have to do?
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Jul 31, 2010
I am using VB.net sockets to send a music file from one instance to another. It currently saves the file, but I do not want to be caught up in file-sharing, so I want to "save" it to a buffer, and when it gets to a particular percentage transferred, I want another thread to play the music file, deleting it from the buffer as it plays. I have the code to send it over the network, but I need to know how to keep it in a buffer and not save it as a file.
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Sep 3, 2011
I've looked and looked + tryed debugging but I'm not getting anywhere fast I'm trying to import a usb radio driver and I'm 99% there. I can turn it on / off and get / set the freq.. but I'm struggling to get the rds name from it. The VB code for the function is
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Jun 8, 2012
I have been asked to improve the memory efficiency of an application that is used for high speed data acquisition. After running the VS memory profiler several times and scanning the projects for obvious issues I came to the following conclusion: despite using a fixed size circular buffer for storing acquired sample points, the RAM usage increases relative to the polling period. For example: polling data for one signal at 2 microseconds can use 5 times more memory (private bytes) than when running at 50 microseconds ... even though the buffer size is the same.
The circular buffer is an array of SamplePoint objects. Each of these objects contains an array of Shorts (16 bit) for corresponding data per signal and one date object (8 bytes) for the time stamp. For efficiency, the circular buffer is Redimmed only once every time it begins polling and filled with empty sample points which are then "assigned".
Also, it seems that when we stop and run the application it hogs even more memory each time as though the Redim is not releasing the previous array. My questions boil down to the following: What is most memory efficient way of implementing a circular buffer containing managed objects which have arrays?Also, how and why is memory usage increasing with a fixed size array with different polling speeds? Does the garbage collector not have time? Do local variables get disposed of IMMEDIATELY when a sub or function exits?These are some of the doubts and concerns that I would like to rule out before proceeding.
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Mar 7, 2012
basically I'm sending and receiving both images, strings and files over a client/server connection. I can easily use a protocol for string commands but I cannot distinguish between the incoming data [if data is image or whatever and then follow onward instructions].So how do I make a packet using Dim buffer as byte()?
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Feb 24, 2010
How can I create a circular buffer on the heap in VB.NET ? This would be used for audio playback via P/Invoke to winmm.dll waveoutopen and waveoutwrite to support development of a software synth. I currently use the marshall class to build a regular array of bytes in the heap.
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Dec 13, 2011
I've been trying to get the double buffer function working in VB.NET GDI+ for a space invaders game using the following command.[code]But because I am using a separate draw routine attached to a class it doesn't seem to work:[code]The aliens draw correctly but the images are very stuttery and double buffering doesn't seem to work.
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