How to: Receive Strings From Serial Ports in Visual Basic. 2 minutes to read.In this articleThis topic describes how to use My.Computer.Ports to receive strings from the computer's serial ports in Visual Basic. To receive strings from the serial port.Initialize the return string. Dim returnStr As String = '.Determine which serial port should provide the strings. This example assumes it is COM1.Use the My.Computer.Ports.OpenSerialPort method to obtain a reference to the port. For more information, see.The Try.Catch.Finally block allows the application to close the serial port even if it generates an exception.
All code that manipulates the serial port should appear within this block. Dim com1 As IO.Ports.SerialPort = NothingTrycom1 = My.Computer.Ports.OpenSerialPort('COM1')com1.ReadTimeout = 10000Catch ex As TimeoutExceptionreturnStr = 'Error: Serial Port read timed out.' FinallyIf com1 IsNot Nothing Then com1.CloseEnd Try.Create a Do loop for reading lines of text until no more lines are available.
DoLoop.Use the method to read the next available line of text from the serial port. Dim Incoming As String = com1.ReadLine.Use an If statement to determine if the method returns Nothing (which means no more text is available). If it does return Nothing, exit the Do loop. If Incoming Is Nothing ThenExit DoEnd If.Add an Else block to the If statement to handle the case if the string is actually read. The block appends the string from the serial port to the return string.
ElsereturnStr &= Incoming & vbCrLf.Return the string. Return returnStrExample Function ReceiveSerialData As String' Receive strings from a serial port.Dim returnStr As String = 'Dim com1 As IO.Ports.SerialPort = NothingTrycom1 = My.Computer.Ports.OpenSerialPort('COM1')com1.ReadTimeout = 10000DoDim Incoming As String = com1.ReadLineIf Incoming Is Nothing ThenExit DoElsereturnStr &= Incoming & vbCrLfEnd IfLoopCatch ex As TimeoutExceptionreturnStr = 'Error: Serial Port read timed out.'
Visual Basic Serial Port Write
FinallyIf com1 IsNot Nothing Then com1.CloseEnd TryReturn returnStrEnd FunctionThis code example is also available as an IntelliSense code snippet. In the code snippet picker, it is located in Connectivity and Networking. For more information, see. Compiling the CodeThis example assumes the computer is using COM1. Robust ProgrammingThis example assumes the computer is using COM1. For more flexibility, the code should allow the user to select the desired serial port from a list of available ports.
For more information, see.This example uses a Try.Catch.Finally block to make sure that the application closes the port and to catch any timeout exceptions. For more information, see. See also.