|
Hi,
I am using USB-to-Serial cable to connect to my device. In my windows application, I use ReadFile/WriteFile to communicate with my device.
Everything is working fine. But one question I would like to ask.
Is DCB setttings important if we are using virtual COM port, eg:
Dcb.BaudRate
Dcb.ByteSize
Dcb.Parity
Dcb.StopBits
Will those settings affect the communication link because we are actually using VIRTUAL COM PORT not the actual port?
Thanks.
|
|
|
|
|
tctan wrote: Dcb.BaudRate
Dcb.ByteSize
Dcb.Parity
Dcb.StopBits
Almost all!
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
Support CRY- Child Relief and You
|
|
|
|
|
So, you mean, even though it is virtual COM port, the DCB setting should also be set properly?
The reason I asked this question is that, someone actually told me that, if you are using virtual com port, you don't need to care about those settings. The only setting concerned is the COM port number.
-- modified at 4:24 Friday 2nd June, 2006
|
|
|
|
|
This may or may not be true depending on the "virtual" COM port.
Sometimes USB devices register themselves as one or more COM ports and those could be called virtual. Different devices behave differently.
I've experienced USB devices used as COM ports that are "enabled" by setting the DTR line, which requires the use of DCB.
However, all COM devices should support the use of DCB, which means that it doesn't hurt to set up things properly. It would also make the code more portable between COM devices.
What you heard regarding not having to set the DCB for virtual COM ports may be true for some specific devices, but certainly not all.
--
Roger
It's supposed to be hard, otherwise anybody could do it!
Regarding CodeProject: "resistance is pointless; you will be assimilated"
|
|
|
|
|
Recently,I am writing a smtp server ,when I test it in the internet ,
I find that it can't send local email to other remote smtp server,
for example smtp.mail.yahoo.com etc.I don't know why?
Can anyone give me some advince?
|
|
|
|
|
I should know pointers by now but still struggle to get code working when dealing with them..
If anyone has any recommended articles I'd be very appreciative. But, the articles dealing with pointer basics don't seem to help me... not sure why. I can understand casting ints, etc. but when it gets to more complex data types, I get confused.
A good example of a tough pointer problem for me is seen below. Not sure why/where I'm reading/changing memory I shouldn't be and I also don't know how I would be able to get the value of the TextualSid in a format usable for strcmp, printf, etc.
Thanks..
//////////
<br />
LPUSER_INFO_23 pBuf = NULL;<br />
LPTSTR TextualSid ;<br />
LPTSTR * TextualSid2= NULL ;<br />
<br />
ConvertSidToStringSid(pBuf, TextualSid2); <br />
<br />
<br />
DWORD sidLen;<br />
sidLen = GetLengthSid(pBuf);<br />
LPDWORD lpdwSize = NULL;<br />
*lpdwSize = sidLen;<br />
GetTextualSid(pBuf->usri23_user_sid, TextualSid, (LPDWORD)lpdwSize);<br />
if (pBuf != NULL) NetApiBufferFree(pBuf);<br />
<br />
Data types used: <br />
<br />
<br />
BOOL GetTextualSid(
PSID pSid,
LPTSTR TextualSid,
LPDWORD lpdwBufferLen
)<br />
{<br />
PSID_IDENTIFIER_AUTHORITY psia;<br />
DWORD dwSubAuthorities;<br />
DWORD dwSidRev=SID_REVISION;<br />
DWORD dwCounter;<br />
DWORD dwSidSize;<br />
<br />
<br />
if(!IsValidSid(pSid)) return FALSE;<br />
<br />
<br />
psia = GetSidIdentifierAuthority(pSid);<br />
<br />
<br />
dwSubAuthorities = *GetSidSubAuthorityCount(pSid);<br />
<br />
<br />
dwSidSize=(15 + 12 + (12 * dwSubAuthorities) + 1) * sizeof(TCHAR);<br />
<br />
<br />
if (*lpdwBufferLen < dwSidSize)<br />
{<br />
*lpdwBufferLen = dwSidSize;<br />
SetLastError(ERROR_INSUFFICIENT_BUFFER);<br />
return FALSE;<br />
}<br />
<br />
<br />
dwSidSize=wsprintf(TextualSid, TEXT("S-%lu-"), dwSidRev );<br />
<br />
<br />
if ( (psia->Value[0] != 0) || (psia->Value[1] != 0) )<br />
{<br />
dwSidSize+=wsprintf(TextualSid + lstrlen(TextualSid),<br />
TEXT("0x%02hx%02hx%02hx%02hx%02hx%02hx"),<br />
(USHORT)psia->Value[0],<br />
(USHORT)psia->Value[1],<br />
(USHORT)psia->Value[2],<br />
(USHORT)psia->Value[3],<br />
(USHORT)psia->Value[4],<br />
(USHORT)psia->Value[5]);<br />
}<br />
else<br />
{<br />
dwSidSize+=wsprintf(TextualSid + lstrlen(TextualSid),<br />
TEXT("%lu"),<br />
(ULONG)(psia->Value[5] ) +<br />
(ULONG)(psia->Value[4] << 8) +<br />
(ULONG)(psia->Value[3] << 16) +<br />
(ULONG)(psia->Value[2] << 24) );<br />
}<br />
<br />
for (dwCounter=0 ; dwCounter < dwSubAuthorities ; dwCounter++)<br />
{<br />
dwSidSize+=wsprintf(TextualSid + dwSidSize, TEXT("-%lu"),<br />
*GetSidSubAuthority(pSid, dwCounter) );<br />
}<br />
<br />
return TRUE;<br />
}<br />
|
|
|
|
|
Hi everyone.
I am trying to implement a chat application that communicates using sockets. The problem is, when i try create a dialog when the application receive a connection request, the DoModal function doesn't works at all.
//Function called from InitDialog of a class derived from CWinThread
void CConexao::Connect()
{
CDlg dlg;
dlg.DoModal()
}
Would anyone help me solving this problem?
Thanks in advance
|
|
|
|
|
Dennis Furlaneto wrote: The problem is, when i try create a dialog when the application receive a connection request, the DoModal function doesn't works at all.
You are wrong! If DoModal doesn't work from threads none of the Dialog based applications will start because CWinApp is derived from CWinThread.
Try to write the code inside InitInstance. This is the function that gets called when an instance of CWinThread starts up or call Connect from InitInstance.
Nibu thomas
A Developer
Programming tips[^] My site[^]
|
|
|
|
|
Well, i didnt't say that CDialog doesn't work with threads... it was a question.
I really didn't say it, but i'm calling connect insitde InitInstance and it is not working.
I think that i have to syncronize the calls, but i don't know how. When i call DoModal, the application will immediatly go back to were i started the thread, not allowing the dialog to be shown.
|
|
|
|
|
Hi again
Just when i thought i'm done this comes up
i wrote this code for testing it compiles ok but
it then crashes at a certain point
can anyone help me find the error
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" \<br />
no_namespace rename("EOF", "EndOfFile")<br />
<br />
<br />
using namespace std;<br />
<br />
void main()<br />
{<br />
<br />
string token="viagra";<br />
HRESULT hr = S_OK;<br />
CoInitialize(NULL);<br />
<br />
try<br />
{<br />
_ConnectionPtr m_pConn;<br />
HRESULT hr =m_pConn.CreateInstance(__uuidof(Connection));<br />
if (FAILED( hr ))<br />
cout<<"Can't create an intance of ADO.Connection"<<endl;<br />
<br />
if (FAILED( m_pConn->Open(_bstr_t("Provider=Microsoft.Jet.OLEDB.4.0;Data Source =bayesfilter.MDB"),<br />
_bstr_t( "" ),<br />
_bstr_t( "" ), <br />
adModeUnknown )))<br />
<br />
cout<<"Can't open datasource"<<endl;<br />
<br />
<br />
<br />
_CommandPtr pCommand;<br />
pCommand.CreateInstance (__uuidof (Command));<br />
pCommand->ActiveConnection = m_pConn;
<br />
string command="SELECT token,Spam,Ham,P,app FROM tblDictionary WHERE token='"+ token;<br />
command+="'";<br />
pCommand->CommandText = command.data(); <br />
<br />
<br />
<br />
_RecordsetPtr pRecordset;<br />
pRecordset.CreateInstance (__uuidof (Recordset));<br />
pRecordset->CursorLocation = adUseClient;<br />
pRecordset->Open ( (IDispatch *) pCommand, vtMissing, adOpenStatic,<br />
adLockBatchOptimistic, adCmdUnknown);<br />
<br />
_bstr_t valField1;<br />
int valField2;<br />
int valField3;<br />
double valField4;<br />
int valField5;<br />
pRecordset->MoveFirst();<br />
if (!pRecordset->EndOfFile)<br />
{<br />
while(!pRecordset->EndOfFile)<br />
{<br />
valField1 = pRecordset->Fields->GetItem("Token")->Value;<br />
valField2 = pRecordset->Fields->GetItem("Spam")->Value.intVal;<br />
valField3 = pRecordset->Fields->GetItem("Ham")->Value.intVal;<br />
valField4 = pRecordset->Fields->GetItem("P")->Value.dblVal;<br />
valField5 = pRecordset->Fields->GetItem("app")->Value.intVal;<br />
printf("%d - %s\n",(LPCSTR)valField1,valField2,valField3,valField5);<br />
pRecordset->MoveNext();<br />
}<br />
}<br />
else<br />
cout<<"No record found insert?"<<endl;<br />
<br />
<br />
m_pConn->Close();<br />
<br />
}catch( _com_error &ce )<br />
{<br />
printf("Error:%s\n",ce.Description);<br />
<br />
}<br />
<br />
CoUninitialize();<br />
<br />
}
Any ideas thanks again
-- modified at 14:41 Thursday 1st June, 2006
|
|
|
|
|
Sorry i forgot to give some more details
The table of the database is tblDatabase and the colums are
token:: text
Spam::Number
Ham::Number
P::Number(with decimal points)
app::number
Thanks
|
|
|
|
|
|
Without actually knowing where it is crashing (and not being able to run it myself), here are the most likely places based on the code:
antonaras wrote: valField1 = pRecordset->Fields->GetItem("Token")->Value;
valField2 = pRecordset->Fields->GetItem("Spam")->Value.intVal;
valField3 = pRecordset->Fields->GetItem("Ham")->Value.intVal;
valField4 = pRecordset->Fields->GetItem("P")->Value.dblVal;
valField5 = pRecordset->Fields->GetItem("app")->Value.intVal;
printf("%d - %s\n",(LPCSTR)valField1,valField2,valField3,valField5);
If GetItem returns NULL for any of those items at any point in time, you will get an access violation. Also, if the types don't match up (that is, if the field is a double and you are checking the int value), you will get strange results that could blow up your stack in a weird place.
Additionally, the printf statement will blow up your stack the way it is written. When you have 2 arguments in the printf string, you should only have 2 variables to match them (you have 2 in the string and 4 trying to match them).
antonaras wrote: m_pConn->Close();
You didn't close the recordset, so at this point, the connection is being closed. Now, when the Recordset smart pointer goes out of scope, it will attempt to close, but it will no longer have a connection. Try adding a pRecordset->Close(); call prior to the connection's close call.
If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week
Zac
-- modified at 15:21 Thursday 1st June, 2006
|
|
|
|
|
antonaras wrote: printf("%d - %s\n",(LPCSTR)valField1,valField2,valField3,valField5);
This should be:
printf("%d - %s\n", valField2, (LPCSTR) valField1);
"The largest fire starts but with the smallest spark." - David Crow
|
|
|
|
|
I was handed down a big windows base project at work that requires some attention. We have been experiencing some random crashes and bugs in the field. I’m working on debugging this issues but I need a little help. We have limited time to debug all issues so I was wondering if there are any commercially available tools (I’m currently looking at SOFTICE) that I could use to monitor the executable and record system parameters when the system is in the field. I need to pin point the root cause of the problems. I’m trying to get a sense of what’s going on in the field that’s causing the random behavior of the executable.
Thank you
|
|
|
|
|
|
this really diserves a 5 
ooh and don't take the Express version because that one is for free 
codito ergo sum
|
|
|
|
|
How is it that correlating the user dump file data with the PDB and source of your application is not sufficient to track this down? Is it memory corruption over time that is suspected? Then make a build that allows periodic memory validation to be performed and dump anything suspicious.
Otherwise, a flat out crash can be diagnosed directly using the user dump file and the Microsoft Debugging Tools. What did you expect the 'good commecrial debugger' to do for you?
People that start writing code immediately are programmers (or hackers), people that ask questions first are Software Engineers - Graham Shanks
|
|
|
|
|
I’m looking for more of a system level debugger. What I was told by a coworker is that there is software that works with you code to track bugs and system information (which was something that he read a long time ago). The "software" goes in the background of the source code and helps to log the parameters that lead up to the crash or the bug. I'm using visual studio when I run the code in debug mode, but I need to know what happens with the system in the field. I will be implementing debugging functionalities but it's going to take some time catch everything and I'm looking for a way to speed this up.
Thank you for all the responses
|
|
|
|
|
The Visual Studio debugger is by far the best debugger for Windows development. There are entire books on a portion of the features it has. If you need something specific that the VS debugger doesn't do (or rather, doesn't give you all the information you would like), check out Compuware. They have some very powerful stuff to help debug a vast array of common issues (e.g. Bounds Checking).
If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week
Zac
|
|
|
|
|
|
I believe Numega Boundschecker does something similar. I used it once upon a time to find some memory leaks and it seemed to work ok, but that was about 7 years ago now. I think boundschecker's still around though in a new form.
When I die I'd like to go peacefully in my sleep like my father, not screaming in terror like his passengers!!!
|
|
|
|
|
As far as I can tell this AppSight stuff is quite different from Boundschecker. The idea is that you instrument an application out in the field - essentially provide it with a black box. Then the customer sends a file back to the developers. They open it in an IDE and you can step backwards and forwards through the code to see what's going on. It's geared towards the common scenario of "it works on the developers' machines but not the customers."
Kevin
|
|
|
|
|
Hi I hope I'm in the right group here.
I am trying to develop an ActiveX control but whenever I compile a debug version of it I am unable to include it in another application. It always gives an error claiming an exception has occurred in ctlnownd.cpp line 443(if I remember correctly). The release version of this control works fine.
I am using VC++ 6 with I think the latest patches although I haven't checked for a while.
Any ideas why this happens and if it can be corrected.
Many thanks
Andrew
|
|
|
|
|
Can you post some code around the point where your program crashes ?
It is also very usefull to use your debugger. Watch the callstack to see which of your function causes the crash.
Cédric Moonen
Software developer
Charting control
|
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
