Clear Serial Buffer Vb Net

A Queue is a generic collection in VB.NET. It implements a FIFO algorithm. With Queue, you can keep a sliding cache of elements, with the one added first always being the first to be removed. Adobe audition for mac crack download. If you are using.NET and the 'SerialPort' class from the 'System.IO.Ports' namespace you could use 'DiscardInBuffer' or 'DiscardOutBuffer' to flush the input or output stream.

In computers, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time. Since the inception of personal computers serial ports are important medium of communication. For example older personal computers used serial interface for mouse, a pointing device.

Clear Buffer and Clear Screen. If you want to clear your terminal screen you can use either the 'Clear buffer' or 'Clear screen' commands. Both are located under the Edit menu. Clear screen will do just that, blank out the terminal screen, but any data received will still be preserved in the buffer. Scroll up in the window to have another look. If you don't need to collect what is waiting in the out buffer of the serialport try calling the serialPort.DiscardWriteBuffer serialPort.DiscardOutBuffer which should clear out whatever has collected there. Thanks to Chad for correcting my error.


Typical serial ports complies to RS-232 communications standard. RS-232 stands for Recommended Standard 232. It is a standard for serial binary single-ended data and control signals connecting between a DTE (Data Terminal Equipment) and DCE (Data Circuit-Terminating Equipment).
Serial ports use 9 pins for connectivity.
Microsoft deprecated support for the RS-232 compatible serial port of the original IBM PC design. Today, RS-232 has mostly been replaced in personal computers by USB for local communications. Compared with RS-232, USB is faster, uses lower voltages, and has connectors that are simpler to connect and use. Both standards have software support in popular operating systems. USB is designed to make it easy for device drivers to communicate with hardware. However, there is no direct analog to the terminal programs used to let users communicate directly with serial ports. USB is more complex than the RS-232 standard because it includes a protocol for transferring data to devices. This requires more software to support the protocol used. RS-232 only standardizes the voltage of signals and the functions of the physical interface pins. Serial ports of personal computers are also sometimes used to directly control various hardware devices, such as relays or lamps, since the control lines of the interface can be easily manipulated by software.
Visual Basic supports Serial port programming using the MSComm Activex Control. To use this control go to Project -> Components.. select Microsft comm control 6.0 and click ok. You will a yellow color telephone icon in controls windows. double click the icon to on to your form.
The important event used by this control is 'OnComm'. This event is fired whenever a communication even occurs such and send / receive data events.
Before using com port you have to initialize the control. The following is the typical intialization properties for com port
With MSCOMM1
.Handshaking = 2 - comRTS
.RThreshold = 1
Buffer .RTSEnable = True
.Settings = '9600,n,8,1'
.SThreshold = 1

Clear Serial Buffer Vb Net Tutorial


.PortOpen = True
' Leave all other settings as default values.
End With
You can put the above code in the Forms load event ( Private Sub Form_Load()). Then put the following block of VB 6.0 code in the oncomm event of the control.
Private Sub MSComm1_OnComm()
Dim InBuff As String
Select Case MSComm1.CommEvent
' Handle each event or error by placing
' code below each case statement.
' This template is found in the Example
' section of the OnComm event Help topic
' in VB Help.
' Errors
Case comEventBreak ' A Break was received.
Case comEventCDTO ' CD (RLSD) Timeout.
Case comEventCTSTO ' CTS Timeout.
Case comEventDSRTO ' DSR Timeout.
Case comEventFrame ' Framing Error.
Case comEventOverrun ' Data Lost.

Serial Buffer Ic

Case comEventRxOver ' Receive buffer overflow.
Case comEventRxParity ' Parity Error.
Case comEventTxFull ' Transmit buffer full.
Case comEventDCB ' Unexpected error retrieving DCB]

' Events

Clear Serial Buffer Vb.net

Case comEvCD ' Change in the CD line.
Case comEvCTS ' Change in the CTS line.
Case comEvDSR ' Change in the DSR line.
Case comEvRing ' Change in the Ring Indicator.
Case comEvReceive ' Received RThreshold # of chars.

Clear Serial Buffer Vb Net Worth

InBuff = MSComm1.Input
Call HandleInput(InBuff)
Case comEvSend ' There are SThreshold number of
' characters in the transmit buffer.
Case comEvEOF ' An EOF character was found in the
' input stream.
End Select
End Sub
The 'comEvReceive' is the important event that is raised when data is received by the com port. You can use appropriate handler functions to deal with the received data. Use MsComm1.Input property to retrieve the data into a variable and manipulate the variable as per your needs. Type MSComm is used in Visual Basic applications to handle weigh machines (in weigh bridge applications), bar code reading devices, IVRS (Interactive Voice Response) Systems and other devices that use serial interface.

Comments

Clear Serial Buffer Vb Network

  • edited 2012-11-21 - 18:01:59
    If I am not mistaken your BS2 program needs a wait command, I will dig up old posts pertaining to this and post a link as soon as I find it.
    Edit: Browse through this thread. It has pretty much everything you need for doing what you want to do,
    http://forums.parallax.com/showthread.php?96973-VB-Express-to-Stamp-Template
  • edited 2012-11-21 - 18:18:07
    If I am not mistaken your BS2 program needs a wait command, I will dig up old posts pertaining to this and post a link as soon as I find it.
    Edit: Browse through this thread. It has pretty much everything you need for doing what you want to do,
    http://forums.parallax.com/showthread.php?96973-VB-Express-to-Stamp-Template

    While I was waiting, I actually did some searching on google and found out my problem. I was using the serialport.readline in vb.net. This reads up to the next line. So what I need to add was CR after the SEROUT message. Example: SEROUT 16, 16468, ['HELLO WORLD!', CR]. This worked.
    Here's my only problem that I need help with. Every time I write to the COM Port and send it, when it returns to the VB Program, it has the original string at the beginning of the line. Sounds confusing. Let me solve that with some code.
    Basically, I use the SerialPort.Write in VB.NET. This writes to the BS2 a number. In this case, '1', '2', or '3'. Next it will send that number multiple times with a decimal after the first two digits. When I send '1', for example, the BS2 receives that, and then sends '11.111'. But when it shows up on the vb.net program, it reads 111.111. It's keeping that first string I sent from the program. How do I clear the SerialPort on the BS2? That way the serial port is clear when I send it, therefore it only shows what I wanted it to show in the first place.
  • edited 2012-11-21 - 18:21:42
    I am pretty sure that is where the RDY and WAIT commands come in to play. I modified the code from that thread and was able to get both Servos and Steppers to work using it.
    VB Code also needs the RDY command:
    This is just examples from the .doc file in that thread. You will need to modify your code accordingly. The stamp can not send and receive data simultaneously and therefor your VB program needs to tell the stamp it is ready to send/rcv and vice versa. At least, that is the way I understood it when I had similar issues.
  • edited 2012-11-21 - 18:42:25
    The original VB.net program was written by Jeff, AKA unsouncode. If you can not get it figured out maybe PM him and I am sure he would be more than happy to help you out. He has helped me dramatically in the past with BS2/VB projects.
  • edited 2012-11-21 - 19:41:50
    The reason you are getting what you send from the PC to the BS2 is because you are using the programming port on the BS2. The way this port is built causes it to echo everything it receives. So in reality, you are getting what you sent and the BS2's response. The only way around this would be to use two I/O pins for Tx and Rx instead of the programming port (pseudo pin 16).
  • edited 2012-11-22 - 11:33:00
    I don't have time right now for a complete answer but in the mean time think about using headers to seperate your data.
    Everything with a header is read as data everthing else is discarded, including the echo
    For example
    VB looks for the 'mydata' header with ReadLine and knows the following string is valid data.
    In VB Readline looks for a string terminated with a Newline character which has a default value of 10, Carriage return has a value of 13. The default NewLine value can be modified in VB
    eg SerialPort1.NewLine=10 or SerialPort.NewLine=13
    This means the default would be SEROUT 16, 16468,
    Changing to SerialPort.NewLine=13 would mean SEROUT 16, 16468,
    Jeff T.
  • edited 2012-11-27 - 12:37:43
    When you say that what you're sending to the BASIC Stamp module seems to be in your input buffer that makes complete sense. The BASIC Stamp modules have a 4.7K resistor between their SIN/SOUT lines, which causes echo. So from the VB application perspective what you send you also receive. From the BASIC Stamp module perspective this never happens because the BASIC Stamps module does not have a serial buffer and since it can perform only one task at a time, all data sent is sent before you can SERIN and see it.