This section will demonstrate how to send and receive data
from the ADR2000 or any other
interface, using Visual C++ and MFC. It outlines the commands used to configure
the serial port, send data out through the serial port, and receive data through the
I am a Windows programmer at one of Ontrak's clients. We use a
custom ADR2000 in our application. I was asked to show how we access the serial port using
Visual C++ with MFC. The sample code was extracted from a program developed for Windows
NT. The program has been tested with Windows 95. I make no effort to explain all of the
parameters used in the various API calls. Please refer to the documentation provided with
your compiler. Those with an MSDN subsrciption may refer to the article "Serial
Communications in Win32"
Commands used in Visual C++ with MFC to access the ADR2000 require
that the following include file be declared at the start of the program.
WINDOWS NT NOTES
Direct access to the hardware is not allowed under Windows NT.
Interaction with the serial port is achieved through a file handle and various WIN32
CONFIGURING THE SERIAL PORT
The first step in accessing the serial port is setting up a file
// variables used with the com port
m_sComPort = "Com1";
m_hCom = CreateFile(m_sComPort,
GENERIC_READ | GENERIC_WRITE,
0, // exclusive access
NULL, // no security
0, // no overlapped I/O
NULL); // null template
Check the returned handle for INVALID_HANDLE_VALUE and then set the buffer sizes.
m_bPortReady = SetupComm(m_hCom, 128, 128); // set buffer sizes
Port settings are specified in a Data Communication Block (DCB). The
easiest way to initialize a DCB is to call GetCommState to fill in its default values,
override the values that you want to change and then call SetCommState to set the values.
m_bPortReady = GetCommState(m_hCom, &m_dcb);
m_dcb.BaudRate = 9600;
m_dcb.ByteSize = 8;
m_dcb.Parity = NOPARITY;
m_dcb.StopBits = ONESTOPBIT;
m_dcb.fAbortOnError = TRUE;
m_bPortReady = SetCommState(m_hCom, &m_dcb);
Communication timeouts are optional but can be set similarly to DCB
m_bPortReady = GetCommTimeouts (m_hCom, &m_CommTimeouts);
m_CommTimeouts.ReadIntervalTimeout = 50;
m_CommTimeouts.ReadTotalTimeoutConstant = 50;
m_CommTimeouts.ReadTotalTimeoutMultiplier = 10;
m_CommTimeouts.WriteTotalTimeoutConstant = 50;
m_CommTimeouts.WriteTotalTimeoutMultiplier = 10;
m_bPortReady = SetCommTimeouts (m_hCom, &m_CommTimeouts);
If all of these API's were successful then the port is ready for
SENDING COMMANDS TO THE ADR2000
To send commands to the ADR2000 the WriteFile call is used. For
example, the following call sends an RE ( read event counter ) command to the ADR2000;
bWriteRC = WriteFile(m_hCom, "RE\r",3,&iBytesWritten,NULL);
The \r escape embeds a carriage return character at the end of the
transmitted string. The ADR2000 uses this to recognize a command.
RECEIVING DATA FROM THE ADR2000
If a command sent to the ADR2000 is a responsive command, that is,
one that results in data being sent back to the host, the data is retrieved using the
bReadRC = ReadFile(m_hCom, &sBuffer, 6, &iBytesRead, NULL);
When you are through using the file handle simply close the file.
I hope that this assists you in your programming efforts.
To retrieve the Visual C++ project used in this example ( 85K ) in
ZIP format ,click "VISUAL C++
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