Serial Port communication - PuTTY emulation - c++

Question

I am writing a simple user interface to communicate with an In-Circuit Serial Programmer. The intention is to remove the need for the end-user to type over a dozen cryptic commands via PuTTY, and in fact to remove the need for typing altogether as the user is inevitably wearing keyboard-unfriendly gloves. The process requires interaction with the user, so a simple batch script is not feasible.
I can find the correct COM port and successfully open it. I can send data, but the response is only ever the equivalent of "unknown command".
I shall refrain from posting the whole code as nobody will be able to recreate my circumstances. However, I can always add everything if necessary.
I open comms using CreateFile() and use WriteFile() or ReadFile() to communicate. For example:
if (!WriteFile(hSerial, "r rc.all\r\n", 10, &bytesRead, NULL))
cout << "Error sending message (" << GetLastError() << ")" << endl;
if (!ReadFile(hSerial, msgBuffer, 15, &bytesRead, NULL))
cout << "No message received" << endl
else
{
cout << "Bytes rcvd = " << bytesRead << endl;
for (int x=0; x<bytesRead; x++)
cout << (unsigned int) msgBuffer[x] << " ";
}
No matter what message I send (either "r rc.all" or "foobar") I always get the same response:
Bytes rcvd = 3
62 13 10
Which is >\r\n. I have tried slowing down the sending of characters to simulate them being typed, but this invokes the same response from the ICSP:
bool serialSend(LPCSTR MESSAGE, PHANDLE hSERIAL)
{
DWORD bytesWritten;
char writeBuff[2];
writeBuff[1] = '\0';
for (UINT x = 0; x <= strnlen(MESSAGE, 64); x++)
{
cout << MESSAGE[x];
writeBuff[0] = MESSAGE[x];
if (!WriteFile(*hSERIAL, writeBuff, 1, &bytesWritten, NULL))
cout << "\t\tERROR! (character '" << MESSAGE[x] << "', error " << GetLastError() << ")" << endl;
Sleep(100);
}
writeBuff[0] = '\n';
if (!WriteFile(*hSERIAL, writeBuff, 1, &bytesWritten, NULL))
cout << "\t\tERROR! (character 'LF', error " << GetLastError() << ")" << endl;
Sleep(100);
writeBuff[0] = '\r';
if (!WriteFile(*hSERIAL, writeBuff, 1, &bytesWritten, NULL))
cout << "\t\tERROR! (character 'CR', error " << GetLastError() << ")" << endl;
cout << endl;
return true;
}
I have set the parameters of the serial connection to match the settings in PuTTY - Byte length, stop bit, parity, flow control, etc. The fact that I get a response at all suggests the connections is not at fault.
What is wrong?

Answer 1

The problem turned out to be the \r\n combination sent at the end of the message.
Sending just \r or just \n does not work. However, sending (char) 13 does - even though that should be the same as \r.
There also needs to be a pause between the sending of each character; 1ms is sufficient.