vb.net serial IO problem

[gene.james@gmail.com]

One of those cases where the problem is probably right under my nose
but I can't see it. This serial test code fails to send the right data:

Private Sub Button3_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles ButtonCAM1.Clic k
Dim TestData() As Byte = {&HFE, &H11, &H11, &HFF}
Using KeyerCom As IO.Ports.Serial Port = _
My.Computer.Por ts.OpenSerialPo rt(KeyerPortNam e, 38400,
IO.Ports.Parity .None, 8, IO.Ports.StopBi ts.One)
KeyerCom.DtrEna ble = True
KeyerCom.Write( TestData, 0, 4)
End Using
End Sub

Checking with a serial monitor, I find that it actually sends code
sends a NUL (&H00) after every byte sent. So the stream actually sent
(as hex)is: FE 00 11 00 11 00 FF 00

Any ideas?

[Chris Dunaway]

Re: vb.net serial IO problem

gene.james@gmai l.com wrote:

One of those cases where the problem is probably right under my nose
but I can't see it. This serial test code fails to send the right data:
>
Private Sub Button3_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles ButtonCAM1.Clic k
Dim TestData() As Byte = {&HFE, &H11, &H11, &HFF}
Using KeyerCom As IO.Ports.Serial Port = _
My.Computer.Por ts.OpenSerialPo rt(KeyerPortNam e, 38400,
IO.Ports.Parity .None, 8, IO.Ports.StopBi ts.One)
KeyerCom.DtrEna ble = True
KeyerCom.Write( TestData, 0, 4)
End Using
End Sub
>
Checking with a serial monitor, I find that it actually sends code
sends a NUL (&H00) after every byte sent. So the stream actually sent
(as hex)is: FE 00 11 00 11 00 FF 00
>
Any ideas?

It sounds like an encoding issue. You could try using the Encoding
class to get a string using a different encoding:

Dim s As String = Encoding.UTF8.G etString(TestDa ta)
KeyerCom.Write( s)

I'm not sure if this will solve your problem, though.

[gene.james@gmail.com]

Re: vb.net serial IO problem


Chris Dunaway wrote:

It sounds like an encoding issue. You could try using the Encoding
class to get a string using a different encoding:
>
Dim s As String = Encoding.UTF8.G etString(TestDa ta)
KeyerCom.Write( s)

Been there. My data is declared bytes because if I encode as UNICODE
UTF8 or ASCII, output for bytes >7F is translated to multi byte strings.

[Chris Dunaway]

Re: vb.net serial IO problem


gene.james@gmai l.com wrote:

Chris Dunaway wrote:

It sounds like an encoding issue. You could try using the Encoding
class to get a string using a different encoding:

Dim s As String = Encoding.UTF8.G etString(TestDa ta)
KeyerCom.Write( s)

>
Been there. My data is declared bytes because if I encode as UNICODE
UTF8 or ASCII, output for bytes >7F is translated to multi byte strings.

Have you tried Encoding.Defaul t?

[Stephany Young]

Re: vb.net serial IO problem

Because SerialPort uses ASCIIEncoding by default, and you have not set any
other Encoding, I would expect your transmission to be translated to {&H3F,
&H11, &H11, &H3F}. That is with all bytes above &H7F (127) translated to
&H3F (63 or ?). This behaviour is clearly stated in the documentation.


<gene.james@gma il.comwrote in message
news:1159886328 .517173.97600@b 28g2000cwb.goog legroups.com...

>
One of those cases where the problem is probably right under my nose
but I can't see it. This serial test code fails to send the right data:
>
Private Sub Button3_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles ButtonCAM1.Clic k
Dim TestData() As Byte = {&HFE, &H11, &H11, &HFF}
Using KeyerCom As IO.Ports.Serial Port = _
My.Computer.Por ts.OpenSerialPo rt(KeyerPortNam e, 38400,
IO.Ports.Parity .None, 8, IO.Ports.StopBi ts.One)
KeyerCom.DtrEna ble = True
KeyerCom.Write( TestData, 0, 4)
End Using
End Sub
>
Checking with a serial monitor, I find that it actually sends code
sends a NUL (&H00) after every byte sent. So the stream actually sent
(as hex)is: FE 00 11 00 11 00 FF 00
>
Any ideas?
>

[gene.james@gmail.com]

Re: vb.net serial IO problem


Stephany Young wrote:

Because SerialPort uses ASCIIEncoding by default, and you have not set any
other Encoding, I would expect your transmission to be translated to {&H3F,
&H11, &H11, &H3F}. That is with all bytes above &H7F (127) translated to
&H3F (63 or ?). This behaviour is clearly stated in the documentation.

You are correct. That is almost the behavior if I send a string it
actually sends 3F 00 11 00 11 00 3F 00. If I say xxx.write (Chr(&FF)) I
will get 3F 00 out of the serial port.
I am sending a byte array and so should not be getting any UNICODE
translation. I am puzzled by the incusion of the NUL after each
character.

I might think there's an anomaly with my serial monitor, but I have
another program that sends these strings and it shows the right data on
the monitor.

[Dick Grier]

Re: vb.net serial IO problem

Hi,

I send binary data frequently, and haven't seen this problem. Are you sure
that the code that you've posted is accurate. I added a button the the
VS2005Terminal example code on my web site as follows:

Private Sub Button2_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button2.Click

Dim TestData() As Byte = {&HFE, &H11, &H11, &HFF}

'Dim TestData(3) As Byte

'TestData(0) = &HFE

'TestData(1) = &H11

'TestData(2) = &H11

'TestData(3) = &HFF

SerialPort.Writ e(TestData, 0, 4)

End Sub


The array initializer code AND the explicit assignment code sent the correct
data (verified by viewing it on a serial data analyzer). Encoding applies
to String data only, not arrays of type Byte -- so, it should work "as
advertised" unless there is something far from my experience. If you send
me email, I can forward the example that I fiddled for this test.

Dick

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition,
ISBN 1-890422-28-2 (391 pages, includes CD-ROM). July 2004, Revised March
2006.
See www.hardandsoftware.net for details and contact information.

[Dick Grier]

Re: vb.net serial IO problem

Actually, I suspect that you have a receiving/viewing problem. If you are
attempting to assign receive data to a String (don't do this!) using
ReadExisting, your code will not work. Instead, you must assign binary data
to an array of type Byte -- using the Read method.

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition,
ISBN 1-890422-28-2 (391 pages, includes CD-ROM). July 2004, Revised March
2006.
See www.hardandsoftware.net for details and contact information.

[gene.james@gmail.com]

Re: vb.net serial IO problem


Dick Grier wrote:

Actually, I suspect that you have a receiving/viewing problem. If you are
attempting to assign receive data to a String (don't do this!) using
ReadExisting, your code will not work. Instead, you must assign binary data
to an array of type Byte -- using the Read method.
>

Thanks. You're right, the code is fine. My serial monitor is not!

My serial monitor program (COMMSNIFFER 1.0.32) WAS tested and working
fine weeks ago ... on an XP box. I was monitoring, however, with a
WinME machine and there the COMMSNIFFER shows that extra NUL. Thinking
I was crazy, I retested COMMSNIFFER on the XP box today and it works
fine there. And so does my code.

Thanks very much for your kind help.
-Gene

[Dick Grier]

Re: vb.net serial IO problem

Hi,

Try my VirtualNullMode m/DataMonitor program (software downloads on my
homepage) and see if this works on your trouble machine.

Dick

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition,
ISBN 1-890422-28-2 (391 pages, includes CD-ROM). July 2004, Revised March
2006.
See www.hardandsoftware.net for details and contact information.