VB 2005 - Serial Pin Change

I want to use "NetworkInformation.NetworkInterface.GetIsNetworkAvailable" to change a couple of pins on my serial port to trigger a local siren type alarm. I know it will probably be very low current so I'll need to use a trigger relay. That's ok. I just need a way of doing it. Any help would be great!

Thanks.

First you'll need to use the System.IO.Ports.SerialPort class to set up your serial port. You just double click the "SerialPort" in the tool box to add one to your form, then you have to set it up (the code, below has 2 SerialPorts on the form). Don't use the Properties Box to set up your serial port, use code.

Here is a code example that sets up one physical serial port 2 different ways but you won't need most of the stuff in these examples:

Code:

---

Public Sub usePort()
        Try
            With SerialPort1
                .PortName = "Com1"
                .BaudRate = 300 
                .Parity = IO.Ports.Parity.None
                .DataBits = 8
                .StopBits = 1
                .ReadTimeout = 100
                .ReceivedBytesThreshold = 1 
                .Handshake = IO.Ports.Handshake.None
                .RtsEnable = True
                .DtrEnable = True
                .Open()
            End With
        Catch ex As Exception
            MsgBox(ex)
        End Try
    End Sub


    Public Sub setModem() 'this sets up the Modem when the Form is loaded, it runs only once.
        Dim atString As String
        atString = "ATE0V0Q1M0S0=1+MS=B103,0,300,300,300,300" & vbCr 'this sets the Hayes modem to be silent, auto answer on 1st ring, & forces 300 baud
        Try
            With SerialPort2
                .PortName = "Com1"
                .BaudRate = 300
                .Parity = IO.Ports.Parity.None
                .DataBits = 8
                .StopBits = 1
                .ReadTimeout = 100
                .ReceivedBytesThreshold = 1
                .Handshake = IO.Ports.Handshake.None
                .RtsEnable = True
                .DtrEnable = True
                .Open()
                .Write(atString)
                .DiscardInBuffer()
                .DiscardOutBuffer()
                .Close()
                .Dispose()
            End With
        Catch ex As Exception
            MsgBox(ex)
        End Try
        usePort()
    End Sub

---

Next thing I think you should look at is a Public Properties of the System.IO.Ports.SerialPort class and use something like DtrEnable or RtsEnable to enable/disable the pins associated with them, then change those pins programmatically to fire your alarm.

The following came from here:
http://weblogs.asp.net/pwilson/archi.../28/34218.aspx

.NET v2.0: Serial Port Communications Finally Arrives
System.IO.Ports.SerialPort (derives from System.ComponentModel.Component) -- Whidbey's MSDN:

Use this class to control a serial port file resource. It provides synchronous and event-driven IO, access to pin and break states, and access to serial driver properties. In addition, its functionality can be wrapped in an internal Stream object, accessible through the BaseStream property, and passed to classes that wrap or utilize streams.

Public Constructors
SerialPort Initializes a new instance of the SerialPort class.

Public Events
Disposed (inherited from Component)Adds an event handler to listen to the Disposed event on the component.
ErrorEvent Represents the method that handles the error event of a SerialPort object.
PinChangedEvent Represents the method that will handle the serial pin changed event of a SerialPort object.
ReceivedEvent Represents the method that will handle the serial received event of a SerialPort object.

Public Fields
InfiniteTimeout Value indicates that no timeout should occur.

Public Methods
Close Closes the port connection, sets System.IO.Ports.IsOpen to false and disposes of the internal Stream object.
CreateObjRef (inherited from MarshalByRefObject)Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.
DiscardInBuffer Discards data from the serial driver's receive buffer.
DiscardOutBuffer Discards data from the serial driver's transmit buffer.
Dispose (inherited from Component)Releases the resources used by the Component.
Equals (inherited from Object)Determines whether the specified Object is equal to the current Object.
GetHashCode (inherited from Object)Serves as a hash function for a particular type, suitable for use in hashing algorithms and data structures like a hash table.
GetLifetimeService (inherited from MarshalByRefObject)Retrieves the current lifetime service object that controls the lifetime policy for this instance.
GetType (inherited from Object)Gets the Type of the current instance.
InitializeLifetimeService (inherited from MarshalByRefObject)Obtains a lifetime service object to control the lifetime policy for this instance.
Open Opens a new serial port connection.
Read Reads from the SerialPort input buffer.
ReadByte Synchronously reads one byte from the SerialPort input buffer.
ReadChar Synchronously reads one character from the SerialPort input buffer.
ReadExisting Reads all immediately available characters (based on the Encoding) in the stream and internal buffer of the SerialPort object.
ReadLine Reads up to the NewLine value in the input buffer.
ReadTo Reads up to the specified value in the input buffer.
ToString (inherited from Component)Returns a String containing the name of the Component , if any. This method should not be overridden. For internal use only.
Write Writes data to serial port output.
WriteLine Writes the specified string and the NewLine value to the output buffer.

Public Properties
BaseStream Gets the internal Stream object, if it exists, for a SerialPort object .
BaudRate Gets or sets the serial baud rate.
BreakState Gets or sets the break signal state.
BytesToRead Gets the number of bytes of data in the receive buffer.
BytesToWrite
CDHolding Gets the state of the carrier detect line for the port.
Container (inherited from Component)Gets the IContainer that contains the Component.
CtsHolding Gets the state of the clear-to-send line.
DataBits Gets or sets the standard length of databits per byte.
DiscardNull Gets or sets whether null characters are ignored when transmitted between the port and the receive buffer.
DsrHolding Gets the state of the data set ready (DSR) signal.
DtrEnable Gets or sets the enabling of DTR during serial communication.
Encoding Gets or sets the character encoding for pre- and post-transmission conversion of text.
Handshake Gets or sets the handshaking protocol for serial port transmission of data.
IsOpen Gets the open or closed status of the SerialPort object.
NewLine Gets or sets the value used to interpret the end of a call to the ReadLine and WriteLine methods.
Parity Gets or sets the parity checking protocol.
ParityReplace Gets or sets the 8-bit character that is used to replace invalid characters in a data stream when a parity error occurs.
PortName Gets or sets the port for communications, including but not limited to all available com ports.
ReadBufferSize
ReadTimeout Gets or sets the number of milliseconds before a timeout occurs when a read operation does not finish.
ReceivedBytes Threshold Gets or sets the number of bytes in the internal input buffer before a ReceivedEvent is fired.
RtsEnable Gets or sets the enabling of RTS during serial communication.
Site (inherited from Component)Gets or sets the ISite of the Component.
StopBits Gets or sets the standard number of stopbits per byte.
WriteBufferSize
WriteTimeout Gets or sets the number of milliseconds before a timeout occurs when a write operation does not finish.

When you start writing your code you can use Intellisense to see all your options. I don't recall which physical pins would be changed with DtrEnable or RtsEnable but I'm sure that is easily found.

Regards,

Ike