Open port USB with vb.net in PDA | Abrir el puerto USB con vb.net en PDA

  • Thread starter Thread starter Slobodan Brcin \(eMVP\)
  • Start date Start date
S

Slobodan Brcin \(eMVP\)

Edgar this is probably wrong NG.

You should check errors returned by CreateFile and other functions.

Use GetLastError to get error code.
Without this error code there is a little that we can do to help you.

BTW: In case that open fails on COM9: try \\.\COM9:

Regards,
Slobodan

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Hi everybody |<es>| Hola a todos

I have a problem with a USB; I can´t open USB port with VB.net for PDA
|<es>| Tengo un problema con el USB; no he logrado abrir el puerto USB con
VB.net

I need send text to a printer RS232 but i can´t;
|<es>| Necesito enviar texto a una impresora RS232 pero no puedo
I have USB to RS232 (Chip PL2303)
|<es>| Tengo un cable USB a RS232 (Chip PL2303)

can you help me? can you tell me how open the port?
|<es>| Prodrian ayudarme? podrian decirme como abrir el puerto?

I use CreateFile() and WriteFile() but it dosen't works
|<es>| He usado CreateFile() y WriteFile() pero no funcina

I also use CreateFile() and DeviceIOcontrol() but it dosen't works
|<es>| Tambien he usado CreateFile() y DeviceIOcontrol() y no funciona


Example Code

<DllImport("coredll.dll")> _
Private Shared Function CreateFile(ByVal lpFileName As String, _
ByVal dwDesiredAccess As Integer, ByVal dwShareMode As Integer, _
ByVal lpSecurityAttributes As Integer, ByVal dwCreationDisposition
As Integer, _
ByVal dwFlagsAndAttributes As Integer, ByVal hTemplateFile As
Integer) As Integer
End Function
<DllImport("coredll.dll")> _
Private Shared Function DeviceIoControl( _
ByVal hDevice As Int32, ByVal dwIoControlCode As Int32, _
ByRef lpInBuffer As Int32, ByVal nInBufferSize As Int32, _
ByRef lpOutBuffer As String, ByVal nOutBufferSize As Int32, _
ByRef lpBytesReturned As Int32, ByRef lpOverlapped As Int32) As
Int32
End Function
<DllImport("coredll.dll")> _
Private Shared Function WriteFile( _
ByVal hFile As Int32, ByVal Buffer As Byte(), ByVal
nNumberOfBytesToWrite As Int32, _
ByVal lpNumberOfBytesWritten As Int32, ByVal overlapped As Int32)
As Int32
End Function

Function PrinterDeviceIO()
idPort = CreateFile("COM9:", GENERIC_READ Or GENERIC_WRITE, 0, 0,
OPEN_EXISTING, 0, 0)

intBF = DeviceIoControl(idPort, FILE_GENERIC_WRITE, 2048, 1,
strValue, strValue.Length, intReturn, intOver)
End Function

Function PrinterWriter()
idPort = CreateFile("COM9:", GENERIC_READ Or GENERIC_WRITE, 0, 0,
OPEN_EXISTING, 0, 0)

intBF = WriteFile(idPort, bytBuffer, bytBuffer.Length, 1024, 0)
End Function
 
API functions usually won't throw exceptions.
Assuming that your CreateFile is successful and you have obtained valid
handle.

WriteFile function will work. Or at least it worked on all USB COM ports I
have used so far.

I fail to see what DeviceIoControl code you have tried to use.

BTW: make sure that GetLastError function returns 0 in all cases after each
function you call.


Regards,
Slobodan

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Thanks Slobodan

But, my code don't return error or Exception code;
I use GetLastError() and all Ok,
At this moment I can open the COM9 but now I need to send text to USB port
for RS232
I use WriteFile() and it doesn't send nothing or even return error or
exception code
I also use DeviceIOcontrol() and it doesn't send nothing or even return
error or exception code

can you help me?

I need a number for IOCTL_XXXXX maybe you can send it with them !

Thanks
Edgar Hdz

|<Español>|
Gracias Slobodan

Pero mi codigo no regresa codigo de error o excepción;
uso GetLastError() y todo funciona,
en este momento he logrado abrir el puerto COM9 pero ahora necesito enviarle
datos a el puerto para RS232
uso WriteFile() y no envia nada ni regresa codigo de error o excepción
tambien uso DeviceIOcontrol() y no envia nada ni regresa codigo de error o
excepción

Puede ayudarme?

Necesito los numeros para IOCTL_XXXXX quizá pueda enviarlo con esto!

Gracias
Edgar Hdz
 
I didn't think that you cant use WriteFile() on a printer port with the NT
kernel, but is this ok with USB?

Regards,

Sean Gahan
 
Edgar,

This is definitely wrong newsgroup for your PDA related questions. You would better off trying something like
microsoft.public.pocketpc.

As Slobodan mention, you better check the return and error (GetLastError.) codes from each API call. And use \\.\COM?".

Also, WriteFile related.. When you send a string from VB to an API, use ByVal prefix. When ByVal precedes a string argument
variable, the address of the null-terminated string data is sent to the procedure. When ByVal is not included, a string descriptor
is sent to the called DLL procedure.
You call may look like: intBF=WriteFile(idPort, ByVaL bytBuffer, bytBuffer.Length, 1024, ByVaL 0&)
 
Hi Sean,
I didn't think that you cant use WriteFile() on a printer port with the NT
kernel, but is this ok with USB?
Click to expand...

??? I fail to see what you are saying/asking. ???

If you are asking if you can use LPT with WriteFile to print raw text or
data then answer is positive. You can write directly to LPT port.

Also you can write to any other thing like COM, USB COM, or any other
virtual COM for that matter.

Implementation or ReadFile, WriteFile, DeviceIoControl is not kernel
related, but more it is related to driver implementation that you opened
with CreateFile.

Regards,
Slobodan

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Slobodan,
I was under the impression that NT had two I/O privilege levels and user
level applications did not have the appropriate privileges to access the
port. Thank you for clarifying that for me.

Regards,

Sean Gahan
 
User application can not access 378h port of 3f8, 2f8, or any other port for
that matter.

But you can use drivers that control that ports some other ports or virtual
devices or what ever to communicate in well in some way unified manners.

You can do only what driver that you have opened trough CreateFile let you
do trough its functionality. (You have no idea if this is real hardware some
simulation or how it is implemented when you look at it from user mode)

Regards,
Slobodan

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Slobodan,
Ok, so I was ½ correct ;)

Is there any part of the Windows OS that you are not familiar with?


Regards,

Sean Gahan
 
Sean,
Is there any part of the Windows OS that you are not familiar with?
Click to expand...

Well I'm bad in high level stuff, like Databases, HTML, and few similar
things.

I'm basically low level programmer, and hardware engineer for instance:
- 8 bit Microcontrollers programming. (Atmel AVR series from 1998, before
that PIC, Z80)
- x86 ASM up to and including SSE2.
- Very long C, C++, MFC, Pascal and Little of Delphi and in old days QBASIC
programming experience
- CP/M, DOS, Win 3.x, Win95 to Win XP all levels of programming. (Mostly
drivers, services, supporting API, COM, etc)
- Very heavy multiprocessor programming and bus utilizations.

List is, well little longer but this cover the basics. So as you can see I
know XPe because I know how things are working behind the hub, if I don't
know of there is no support for what I need well then I sit and write
support I need :-) Simple isn't it.


Regards,
Slobodan

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