C / C++ / MFC

Visual C++ - Serial communication.

28-Jun-05 20:34

Hi Maria
You need not install any TAPI libraries, let alone for third party drivers. If you are going for a simple TAPI framework first and then develop on it there are solutions to it. Check out this link:
http://www.codeproject.com/vbscript/tapi.asp[^]
http://www.codeproject.com/useritems/SMDR_based_on_TAPI_22.asp[^]
Bye... All the best
Regards
Sreekanth Muralidharan
INDIA

Sreekanth Muralidharan,
Corporate Systems Consultant [Embedded Systems],
INDIA

Vishwas37198427-Jun-05 0:55

Vishwas371984

27-Jun-05 0:55

Why does ReadFile function hang after successfully reading a byte from port?

Phil J Pearson27-Jun-05 1:12

27-Jun-05 1:12

You must give more detail about the problem if you want help.

The opinions expressed in this communication do not necessarily represent those of the author (especially if you find them impolite, discourteous or inflammatory).

Vishwas37198427-Jun-05 1:28

Vishwas371984

27-Jun-05 1:28

I wrote a program in Visual C++ to implement Serial Communication. The program compiles successfully and runs also. After initialising the ports, when a byte is written to the port, on one computer and is read on another computer (which is connected to the earlier computer) the code works. But when I try to read the port again the program simply hangs. The only way out is then to stop the debugger.

I used the initialisation code provided in a article posted on this site itself (the one written by Eshwar). But to implement read and write I only used the functions ReadFile and WriteFile respectively.

Cedric Moonen27-Jun-05 1:35

Cedric Moonen

27-Jun-05 1:35

If there is no data coming on the port anymore and if the read timeout of the port is set to infinite, the ReadFile function will wait until data is received (thus it seems to 'hang').
To change this behavior, you can use the SetCommTimeout function.

But I suggest you to read a little more documentation about how serial ports work because you seem to lack some important informations there...

Hope this helps

Vishwas37198427-Jun-05 18:14

Vishwas371984

27-Jun-05 18:14

Respected Sir,
I read your suggestion and tried setting the timeout to a lower value. I set it to the following values :-
commTimeout.ReadIntervalTimeout = 10;
commTimeout.ReadTotalTimeoutConstant = 10;
commTimeout.ReadTotalTimeoutMultiplier = 1;
commTimeout.WriteTotalTimeoutConstant = 10;
commTimeout.WriteTotalTimeoutMultiplier = 1;
Still no use. The ReadFile function makes the program hang. Please can you suggest some sample values.
Thanking you.

Phil J Pearson27-Jun-05 1:37

27-Jun-05 1:37

Still not enough information. It is well known that ReadFile and WriteFile both work. The problem must be in your code. Post some sample code.

It may be simply that you call ReadFile again when there is nothing for it to read; what if you send it another byte from the other computer?

The opinions expressed in this communication do not necessarily represent those of the author (especially if you find them impolite, discourteous or inflammatory).

how to search database usig ado in vc++??

khan++27-Jun-05 1:47

khan++

27-Jun-05 1:47

In non-overlapping mode, when you call ReadFile, it will wait until it reads a byte at least. It also depends on the input size as I remember.
You really should not call ReadFile or WriteFile in your main thread, you better use another thread to do this, which will keep your program responding, and it is better to use proper time-out values for the port, so that ReadFile will fail after a certain amout of time if nothing is read.

Does that do any help?

this is this.

smartymanav27-Jun-05 0:41

smartymanav

27-Jun-05 0:41

Hiii

i have used ADO for linking my database in vc++...
how can i add a function which searcges for a particular value in a field....

please help

manav

Phil J Pearson27-Jun-05 1:17

27-Jun-05 1:17

Use an ADO recordset with a query like

"SELECT * FROM [Table] WHERE [FIELD]=value;"

The opinions expressed in this communication do not necessarily represent those of the author (especially if you find them impolite, discourteous or inflammatory).

toxcct27-Jun-05 1:19

toxcct

27-Jun-05 1:19

i doubt you code this directly in C++...

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Phil J Pearson27-Jun-05 1:39

27-Jun-05 1:39

No, of course not! Poke tongue | ;-P

You use a recordset, (coded in C++) which needs a query string like the one I showed.

The opinions expressed in this communication do not necessarily represent those of the author (especially if you find them impolite, discourteous or inflammatory).

T h r e a d s a r e t h r e a d i n g ! !

toxcct27-Jun-05 1:30

toxcct

27-Jun-05 1:30

you could use Carlos Antollini's ADO Classes[^]

cheers,

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Sreekanth Muralidharan26-Jun-05 23:43

26-Jun-05 23:43

Hi
This is again a problem with thread. The thread is affected by programs running on the background. It is affected by the programs showing in the system tray. Is there any way to close all programs and processes other than my application and related processes and threads.
Help Me Soon.
Regards

Sreekanth Muralidharan,
Corporate Systems Consultant [Embedded Systems],
INDIA

ThatsAlok26-Jun-05 23:56

ThatsAlok

26-Jun-05 23:56

Sreekanth Muralidharan wrote:
Is there any way to close all programs and processes other than my application and related processes and threads.

EnumProcess and then Use WM_QUIT to kill Process other than you!

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta

Sreekanth Muralidharan28-Jun-05 20:30

28-Jun-05 20:30

Hi Alok
You are back again!! Glad for me !!
Thanks a lot. Will check that and shoot you a reply.
Shall we now open bottles?
Regards
Sreekanth Muralidharan

Sreekanth Muralidharan,
Corporate Systems Consultant [Embedded Systems],
INDIA

ThatsAlok28-Jun-05 22:38

ThatsAlok

28-Jun-05 22:38

Sreekanth Muralidharan wrote:
Shall we now open bottles?

Your Wish Smile | :)

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta

Sreekanth Muralidharan29-Jun-05 19:59

29-Jun-05 19:59

Hi Alok
See.. If I am setting the priority of the application process as a REALTIME_PRIORITY_CLASS in its OnInitDialog() function (if not in this function, where?) and setting the thread created by that application using SetThreadPriority() (calling in the thread itself) to TIME_CRITICAL_PRIORITY level , what would be the priority of the thread that I have created? Can any process or thread interrupt the thread I have created?
Regards
Sreekanth Muralidharan
Hyderabad

Sreekanth Muralidharan,
Corporate Systems Consultant [Embedded Systems],
INDIA

ThatsAlok29-Jun-05 20:33

ThatsAlok

29-Jun-05 20:33

Sreekanth Muralidharan wrote:
TIME_CRITICAL_PRIORITY level , what would be the priority of the thread that I have created? Can any process or thread interrupt the thread I have created?

According to MSDN, REALTIME_PRIORITY_CLASS :-" A thread with a base priority level above 11 interferes with the normal operation of the operating system. Using REALTIME_PRIORITY_CLASS may cause disk caches to not flush, hang the mouse, and so on.
"
So i believe no process or thread wil interrupt your high priority thread Smile | :)

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta