Reading serial port.....
Hi all,
I am developing for a windows CE.NET device.... I am using Serial IO class in Smart Device Framework found on the following page
http://www.opennetcf.org/CategoryView.aspx?category=Home
to develop an application that will read data from GPS on a Serial Port..... The class exposes an event SerialPort_DataReceived() which is fired each time a new character is received at the Comm Port(Similar to OnComm in VB6)..... Using the following code I am able to display whatever comes on the serial port in a Textbox.......
Private Sub SerialPort_DataReceived() Handles SerialPort.DataReceived
Dim Buffer(SerialPort.InBuffer
Buffer = SerialPort.Input
TextBox1.Text = TextBox1.Text & (Encoding.ASCII.GetString(
End Sub
For those who donot know about GPS the following are the six GPS strings that the receiver sends every second to the Serial port which we can read...
$GPGGA,<1>,<2>,<3>,<4>,<5>
$GPGLL,<1>,<2>,<3>,<4>,<5>
$GPGSA,<1>,<2>,<3>,<3>,,,,
$GPGSV,<1>,<2>,<3>,<4>,<5>
$GPRMC,<1>,<2>,<3>,<4>,<5>
$GPVTG,<1>,T,<2>,M,<3>,N,<
Out of these 6 strings only 2 are of my interest and they are GPGGA and GPRMC..... So I want some intelligence in the SerialPort_DataReceived() event so that whenever I have received both GPGGA and GPRMC an event is fired that will tell me that both the strings are ready to be used......
I hope my question is clear now.....
Imran
I am developing for a windows CE.NET device.... I am using Serial IO class in Smart Device Framework found on the following page
http://www.opennetcf.org/CategoryView.aspx?category=Home
to develop an application that will read data from GPS on a Serial Port..... The class exposes an event SerialPort_DataReceived() which is fired each time a new character is received at the Comm Port(Similar to OnComm in VB6)..... Using the following code I am able to display whatever comes on the serial port in a Textbox.......
Private Sub SerialPort_DataReceived() Handles SerialPort.DataReceived
Dim Buffer(SerialPort.InBuffer
Buffer = SerialPort.Input
TextBox1.Text = TextBox1.Text & (Encoding.ASCII.GetString(
End Sub
For those who donot know about GPS the following are the six GPS strings that the receiver sends every second to the Serial port which we can read...
$GPGGA,<1>,<2>,<3>,<4>,<5>
$GPGLL,<1>,<2>,<3>,<4>,<5>
$GPGSA,<1>,<2>,<3>,<3>,,,,
$GPGSV,<1>,<2>,<3>,<4>,<5>
$GPRMC,<1>,<2>,<3>,<4>,<5>
$GPVTG,<1>,T,<2>,M,<3>,N,<
Out of these 6 strings only 2 are of my interest and they are GPGGA and GPRMC..... So I want some intelligence in the SerialPort_DataReceived() event so that whenever I have received both GPGGA and GPRMC an event is fired that will tell me that both the strings are ready to be used......
I hope my question is clear now.....
Imran
ASKER
This is the VB6 version that I got here on EE..... It is working very well in VB6 and eVB but I have not been able to port it to VB.NET
Private sBuffer as string
Private sString as string
Private Sub MSComm1_OnComm()
Select Case MSComm1.CommEvent
Case comEvReceive ' Received RThreshold # of chars.
sBuffer = sBuffer & MSComm1.Input
Do Until Len(sBuffer) = 0
Call ProcessCom(Left(sBuffer, 1))
sBuffer = Mid(sBuffer, 2)
Loop
End Select
End Sub
Private Sub ProcessCom(cChar As String)
If cChar <> vbCr And cChar <> vbLf Then
sString = sString + cChar
End If
If cChar = vbLf Then 'End Of Line
If InStr(sString, "GPGGA") > 0 Then 'Valid Line
msgbox "Do what needs to be done here."
sString = ""
End If
End Sub
Imran
Private sBuffer as string
Private sString as string
Private Sub MSComm1_OnComm()
Select Case MSComm1.CommEvent
Case comEvReceive ' Received RThreshold # of chars.
sBuffer = sBuffer & MSComm1.Input
Do Until Len(sBuffer) = 0
Call ProcessCom(Left(sBuffer, 1))
sBuffer = Mid(sBuffer, 2)
Loop
End Select
End Sub
Private Sub ProcessCom(cChar As String)
If cChar <> vbCr And cChar <> vbLf Then
sString = sString + cChar
End If
If cChar = vbLf Then 'End Of Line
If InStr(sString, "GPGGA") > 0 Then 'Valid Line
msgbox "Do what needs to be done here."
sString = ""
End If
End Sub
Imran
So you are able to Display the data in TextBox is it???
Private Sub SerialPort_DataReceived() Handles SerialPort.DataReceived
Dim Buffer(SerialPort.InBuffer
Buffer = SerialPort.Input
TextBox1.Text = TextBox1.Text & (Encoding.ASCII.GetString(
End Sub
What does it display?? The first line you posted from the GPS data ????
Private Sub SerialPort_DataReceived() Handles SerialPort.DataReceived
Dim Buffer(SerialPort.InBuffer
Buffer = SerialPort.Input
TextBox1.Text = TextBox1.Text & (Encoding.ASCII.GetString(
End Sub
What does it display?? The first line you posted from the GPS data ????
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Hi TheLearnedOne
That's the way of course but it depends how the data is streaming
I mean if all the Lines are recieved in one go then your code will work fine
If the lines come one by one say after a small delay then he will need to Test for
GPGGA and GPRMC separately
That's why I asked what does his code show in text Box
Anyway in case its one line at a time you can just change the AND to OR
If testString.IndexOf("GPGGA"
RaiseEvent ValidData(testString)
End If
That's the way of course but it depends how the data is streaming
I mean if all the Lines are recieved in one go then your code will work fine
If the lines come one by one say after a small delay then he will need to Test for
GPGGA and GPRMC separately
That's why I asked what does his code show in text Box
Anyway in case its one line at a time you can just change the AND to OR
If testString.IndexOf("GPGGA"
RaiseEvent ValidData(testString)
End If
ASKER
>>What does it display?? The first line you posted from the GPS data ????
No it displays all the data coming from the GPS....
I hav tried the code that you have suggested.... It is almost working fine.... Only a couple of problems....
1) testString.Index("GPRMC") > -1 is generating compile error that Index is not a member of String... I have replaced it with IndexOf..... Have I done it right????
2)If testString.IndexOf("GPGGA"
This condition is even true when the whole GPRMC string has not reached..... What I need to make sure is that even after testString.IndexOf("GPRMC"
Imran
No it displays all the data coming from the GPS....
I hav tried the code that you have suggested.... It is almost working fine.... Only a couple of problems....
1) testString.Index("GPRMC") > -1 is generating compile error that Index is not a member of String... I have replaced it with IndexOf..... Have I done it right????
2)If testString.IndexOf("GPGGA"
This condition is even true when the whole GPRMC string has not reached..... What I need to make sure is that even after testString.IndexOf("GPRMC"
Imran
That was untested code, since I don't have any serial device:
testString.IndexOf
Bob
testString.IndexOf
Bob
ASKER
This is the logic I am using......(It is successfull)
If testString.IndexOf("GPRMC"
If testString.LastIndexOf(vbC
Call ValidData(testString)
'Me.Invoke(New EventHandler(AddressOf ValidData(testString)))
_buildInput.Remove(0, _buildInput.Length)
End If
End If
Please suggest me if it can be done more efficiently??? The reason I am more concerned about it, is that it will run all the time my program is running.... and I want to make sure that it is the most efficient and there is no memry leak in it..... I am looking forward for your reply and better suggestions.....
Imran Arshad
If testString.IndexOf("GPRMC"
If testString.LastIndexOf(vbC
Call ValidData(testString)
'Me.Invoke(New EventHandler(AddressOf ValidData(testString)))
_buildInput.Remove(0, _buildInput.Length)
End If
End If
Please suggest me if it can be done more efficiently??? The reason I am more concerned about it, is that it will run all the time my program is running.... and I want to make sure that it is the most efficient and there is no memry leak in it..... I am looking forward for your reply and better suggestions.....
Imran Arshad
SOLUTION
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ASKER
Please suggest that raising an event will be more efficient or calling a function
RaiseEvent ValidData(testString)
or
call ValidData(testString)
and also you have suggested to use
_buildInput = New StringBuilder()
instead of
_buildInput.Remove(0, _buildInput.Length)
So will VB.NET do the memory management for me??? I mean I will be each time decalaring an object of the class StringBuilder.....
Please forgive me for the silly questions I am asking as I am very new to VB.NET.... Only 1 week since I have been working on VB.NET......
Imran
RaiseEvent ValidData(testString)
or
call ValidData(testString)
and also you have suggested to use
_buildInput = New StringBuilder()
instead of
_buildInput.Remove(0, _buildInput.Length)
So will VB.NET do the memory management for me??? I mean I will be each time decalaring an object of the class StringBuilder.....
Please forgive me for the silly questions I am asking as I am very new to VB.NET.... Only 1 week since I have been working on VB.NET......
Imran
ASKER
Maybe you can also help me in the other question that I have asked at
https://www.experts-exchange.com/questions/21375061/Bitmap-related.html
Imran
https://www.experts-exchange.com/questions/21375061/Bitmap-related.html
Imran
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ASKER
One last question:
Imagine a case when the function call ValidData(testString) takes more then 1 second to complete..... But the data stream continuously arrives and I will receive GPRMC in one second..... Now I am still in the ValidData function(Doing some manipulations there) and I will be calling it again...... What will happpen? Will the function be called again even if I havenot exited from the earlier function call?
Imran
Imagine a case when the function call ValidData(testString) takes more then 1 second to complete..... But the data stream continuously arrives and I will receive GPRMC in one second..... Now I am still in the ValidData function(Doing some manipulations there) and I will be calling it again...... What will happpen? Will the function be called again even if I havenot exited from the earlier function call?
Imran
ASKER
Imran