USB SerialPort Oddities .Net 4.0?
Jul 12, 2011
Recently while trying to help someone with an issue using USB SerialPort's I discovered sometheing interesting when the ports Handshake was set to RequestToSend. My setup COMx <---> BreakOutBox <---> COMy COMx and COMy are on the same PC. The breakout box is used to create a null modem, pins 2 & 3 crossed, pin 20 to pin 6.When the handshake was set to RequestToSend every Write resulted in Carrier Detect and Ring being raised. Is this just my adapter or are all USB SerialPorts like this?Serial Port Random Microsoft® Community Contributor 2011
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Apr 23, 2011
I am trying to read caller id from a internal modem. modem is caller id enable and it works in hyper terminal. but when i try from vb.net it only shows 'RING'. here is my full code
[Code]...
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Dec 16, 2011
I am using VB 2005 and need to trap a serial port timeout. I use a standard try/catch block, but if no characters arrive the code still hangs at the ReadByte call. Here is the code:
Try
SerialPort.ReadTimeout = 200
' read timeout of 200 mSecs
thisByte = SerialPort.ReadByte()
[code]....
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Jun 23, 2010
I have wrote this program (for PDA), to connect a PDA to the PC via RS232.It only works half way.
If I send anything from the pda to the pc, I receive data correctly.If I send anything from the pc, then the pda hangs up.Can anybody tell me what I'm doing wrong?
Also, how do I make sure the port on PDA is closed when quitting the application?
[Code]...
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Sep 23, 2011
Looking for serial port communication using ASP.NET 4.0. I have a cardwriter/reader from IDTECH which talks through a comport. Is there any way to accomplish with .net through the web.
I read things but most of the topics on speaking about .net 2.0 and I was not sure if they created something to handle this in .net 4.0
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Jun 16, 2011
We have been debugging a problem with serial communications with an embedded device on 115200 baud, Even parity, 8 databits and 2 stopbits. The problem: a lot of extra 0x00 are sometimes received from the serialport.
1) We build a real basic sample program that only handles the data exchange. It was completely build according the serial-port-vb.doc from msdn. It was build in vb.net 2010. So this was the most basic setup possible on the PC side. This simple tool clearly shows the datareceived event spitting out extra bytes.
2) We used a scope to look at the hardware bits/levels. No problems / differences seen between good and bad messages. No extra bytes visible that the serialport event send to our programm.
3) We tapped the serial communication and received no wrong data on the tapping system but still on the .net tool. Again the serialport datareceived event gave us many extra 0x00 bytes.
So our only possible conclusion is that there is a problem in the serialport component from .net. My question: Are there any know issues? Can I get in contact with a microsoft engineer?
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Mar 16, 2009
I want to send some data through a serialport (USB) permanently and got a problem once the USB interface crashes. Sometimes it just happens, but if I ask the PC "serialport2.isopen ()" I will get a TRUE, even though the USB cable was uplugged. How can I check if a connection is still available. CDHolding wasnt working either. I am using VB 2008 Express
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Jan 27, 2009
how to use the SerialPort in Visual Basic Express?
I have this in the Serial Port Data Recieved event
Code:
SerialText = SerialText & SerialPort1.ReadChar
TextBox1.Text = SerialText
I get : Cross-thread operation not valid: Control 'TextBox1' accessed from a thread other than the thread it was created on. As soon as the event is triggered.
I'd like to display the recieved info in a textbox and transmitt info as well, but I don't know how...
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Jan 7, 2011
i am coding a tool which is able to connect GPS devices over the IO.Ports.SerialPort function in .NET..Everything works fine, but to list all available COM interfaces it looks like: [code] its impossible to connect to a device which is called COM3°. If i simply try to connect manually to COM3 it works perfect. [code]
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Aug 3, 2009
I have an application that requires several threads, otherwise the main UI thread would end up frozen.i am after a little advice as i have not really don alot of threaded applications.
First Question;
I have a thread which handles data coming in from the serial port( this wil become much more complicated), is it safe to use a synclock on the serialport object : -
[code]...
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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 3, 2010
I'm trying to enable a timer within a SerialPort.PinChanged even is reached but the timer tick even never starts. Has anyone ever tried this? I am using vb.net 2008 express so I dont know if that is the issue or not.
[Code]....
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Mar 10, 2010
I'm using the following to read a serial port. When run it displays the data correctly but stepping through the program I find that it loops through the serialdatarecieved event for each character of the port input rather than reading all of it. So _msg only equals one letter at a time. I'm trying to set a variable equal to the entire input stream but only get one character of it.The end goal is to capture all of the data available on the port when the event triggers so that this data can then be processed. I tried using the bytestoread function, which gets the correct number of bytes to read, and then looped through to read a byte at a time but that didn't seem to work as I expected either. It just kept reading the first byte.
Imports System.IO.Ports
Public Class CommTest
Dim WithEvents SerialPort As New SerialPort
[code]....
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Apr 7, 2011
I am doing a sms project using VB .net to connect to my gsm modem via serialport. All the connection and everything was working great and I can send and receive sms. Then here come a problem, I need to send long sms more than 160 chars. I read and did some research and I know that I need to use the pdu and udh. I managed to understand slightly of the pdu packet but is still quite confuse on that part.
Anyone can briefly explain the exact way to do the concatented sms (long sms)?Another problem is how can I use vb to encode the data into pdu gsm 7bit data? Is there any built in functions or do i need to write them myself?
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Mar 14, 2009
I am trying to access a printer via the serial port in VB Express 2008. I wrote a small prog with buttons on the form to exercise the escape codes in a Windows Vista 32 laptop with a USB to serial adapter. Only 3 codes worked, BEL, reset and a printer specific command. Also, when i try to receive data, it justs times out. So, I tried to move to a WinXP machine with real serial ports. The program now has an illegal argument exception and the message is to the effect that the name of the port for the property portName does not start with COM/com. Which is very puzzling because I did verify the portname and it is com1.Is this a known issue or am I doing something wrong? The form works on Vista but not in XP.
[Code]...
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Apr 4, 2012
I am writing a program which detects a development board I designed which communicates with an FTDI chip. Right now my program scans any COM ports and generates a list, which the user will then choose from and connect with that device. The problem is that I want to isolate that list to only the devices which I designed. The FTDI has a unique manufacturer and device ID, but I only know how to access this data 'the old fashioned way' (i.e. through device manager).
What I would like to know how to do is determine the VID and PID of a COM port from VB, so I can dynamically get rid of any devices which do not meet the proper requirements and thus my list will only show the correct devices.
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Aug 21, 2009
I'm working on application which uses SerialPort Control to send/receive commands to/from microcontroller.
Here is the basic
CODE:
I maybe missing something because the reaction of microcontroller very accidential! I mean, sometime it works from the first click and sometime from the third... I must make a number of clicks until it reacts back!
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Jun 23, 2010
I am trying to send and receive data using the SerialPort component. I am sending data to an Texas Instruments MSP430 which simply echos the sent character. I wanted my VB solution to read characters from a file, send a single character, and wait until the echoed character is received before sending another.
I have been fairly successful thus far but I have run into a little catch. When I attempt to send large files (323505+ characters) my MSP430 just hangs there and will not receive any more characters. My VB app return to VS '08 with timeout errors (timeout set to 1 minute).
I wanted to post my VB code here to see if the problem is from my VB app. I will be posting this problem on the IT usergroup to sort out anything on the MCU end. Here is the pastbin of the data write and the data receive subs:[URl]..
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Aug 25, 2009
I'm using one form to make contact with the serial port with the next
Imports System.IO.Ports
Imports Microsoft
Public Class Menu
[Code].....
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Nov 9, 2009
output.gif?I've just upgraded to Visual Studio 2008 and have been given a project and getting gps string from a radio via the serial port. I used a program called "SerialWatcher" and it monitors the data coming in from the radio. It works perfectly. When I tell it the port and settings, click Open, I get consistent output. Here is an example of the data that I got:
<NUL><STX>$PKLDS,124043,A,3337.8562,N,08418.8077,W,000.0,146.5,091109,,00,101,2190,80,00,*1C<CR><LF><ETX><STX>$PKLDS,124104,A,3357.1421,N,08403.0604,W,000.0,000.0,091109,3.0,W00,101,3003,80,00,*61<CR><LF><ETX><STX>$PKLDS,124128,A,3354.1213,N,08414.3434,W,000.1,274.3,091109,4.9,W00,101,2576,80,00,*64<CR><LF><ETX>
[code].....
The little icon symbol before the dollar sign is actually two symbols which I think are the <stx> and <etx>. I'm including a screenshot to show what they actually look like. From the output my program created all I would need is actually the last line. I can't really check for "length" because some data received by the radio will be half that length (or more than half). But there should always be a start and end (regardless of what is in the middle) I would think.
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Nov 20, 2009
I have a program that is hooked to an external device via rs232. I can send and receive messages to this device just fine using the ReadLine() method of the serial port. This allows me to send a command and wait for a response in a synchronous manner. However, when I start the program I need to check the status of the device. If the device is in a sleep state, off, or on, I send a command and get a response, however, if the machine is unplugged, I get nothing so my program will hang waiting for a response before continuing. I would like to abort the readline after 1 minute and display a message that the external device is not connected or having a problem, etc. and allow the program to load. The command I use to check the device is:
Do Until Mid(balanceStatus, 1,3) = "S S" 'This is the return command that the status is read
spBlance.Writeline ("S")
balanceStatus = spBalance.Readline 'This will cause the program to hang if the external device is unavailable[code]....
That readline is causing the program to hang. So I need a way to abort if it exceeds a certain time (around 1 minute). I was trying to use the DataReceived Event of the serial port, but I need to wait for a response before continuing and DataReceived fires on its own thread.If there is a way to abort the thread, I was thinking of doing a timer control.
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Apr 24, 2009
I am trying to run the function:
Code:
Private Sub port_dataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles port.DataReceived
from inside a while loop of a different function ie.
Code:
While A_switch = 0
System.Threading.Thread.Sleep(100) ' Sleep for .1 second
calabrate_send = calabrate_send - 5
[code]....
the real problem is that the serial call updates the value of A_switch which is need to exit the loop at the correct time?
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Feb 17, 2009
I am using VB2008 SerialPort to communicate with a device. My problem is, using RTS handshake I am missing the first 50 or 60 chars, after that everything is intact. I tried to change the buffer size - Has no effect, used standard, bigger, smaller and no change.
The device timing says when it sends CTS signal, it will start listening 100ms after that. I have no clue how to delay the write to test this. Should I first write to the buffer then write to the port after a a 100ms timer event?
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Jun 4, 2009
I have a problem with this two controls. I have a software in VB6 which send a command to hardware in ASCII type: 170 - head, 3 - numb. of command, CRC.
[Code]...
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Mar 10, 2010
I have a .dll provided by a vendor and it requires me to pass a handle to the com port the device is represented as in order to access some other functions. Can I get the handle from the SerialPort object? The device I'm working with is a USB-UART converter chip with auxiliary I/O. I need to access the I/O which involves using a Visual C++ 6.0 .dll which is the one that requires the handle to the Com port.
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Sep 21, 2009
I've seen this great example of serial communication in VB.NET[URL]..I try to use it in a project I am working on but somethings are not clear to me.1: Now the send and received data is shown in one RichTextBox but I would like to split this into two RichTextBoxes (RtbSend and RtbReceived).It is unclear to me how and were data is assigned to the RichTextBox?
2. the received data is shown in the Richtextbox as one long line, I would like to get a new line for every send message.So for example: I I send "test" four times, I would like to see:The example describes that "comPort_DataReceived" is executed when data is waiting in the buffer. Where can I see the eventhandler responsible for this? How does it know data is waiting?The problem is this kind of coding is a bit to difficult for me. I want to understand the code before I implement it into my project. I understand most of the code but this is unclear to me.
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Mar 7, 2012
I develop a simple application usiing VB.NET, VisualStudio 2008, that read input from a serial port
(from another device). I use the class SerialPort.
Using HyperTerminal I can see the input , it's fine. looks like :
S0P,A,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0 S0P,A,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
[Code]...
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Mar 2, 2012
i am receiving data from serial port and i update a richtextbox in a MDI Form with the control.invoke method
(Code in SerialPort.DataReceived Event)
If myTerminal.Visible Then
myTerminal.MyRichTextBox1.Invoke(New MethodInvoker(Sub()
myTerminal.MyRichTextBox1.AppendText(dataLine & vbCrLf)
End Sub))
End If
But as a mdi form it has the ability to close and reopen. So when the serialport is sending data to richtextbox and the user click the close button and the form gets disposed. Then the error "Invoke or BeginInvoke cannot be called on a control until the window handle has been created."...
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Feb 10, 2012
I am writing VB.NET codes in both Window form and DLL.
In the Window form program, no problem I have. She can open serial ports, write, and handle receive interruption with the code below[code]...
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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.
[Code]...
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