_com_error at memory location 0x00BCF818 due to HRESULT initialization

Sai Prashanth Josyula 1

I am very new to C++ programming and I have to run the below code in order to achieve communication via a COM port to an external device. Most of the below code is regarding what to do once the communication is established ( I assume). I am unable to get the desired output out of the code due to a series of exceptions starting with the following.

Exception thrown by comip.h
Unhandled exception at 0x7597A6F2 in UnmanagedC++Example.exe: Microsoft C++ exception: _com_error at memory location 0x00DBFE48.

Starting part of the code that is actually causing all these errors is :

#include "stdafx.h"
#include "tchar.h"
#include "windows.h"
#include "comip.h"
#import "D:\PhD_Work\NanoPro\CommandsPD4I.tlb" raw_interfaces_only
using namespace CommandsPD4I;

int _tmain(int argc, _TCHAR* argv[])
{
    **// Initialize COM.
    HRESULT hr = CoInitialize(NULL);**
//And the code goes on....

Kindly give me your inputs. I am working in Visual Studio 2019

Cheers
Prashanth

Song Zhu - MSFT 906 Reputation points

2021-06-15T06:15:32.127+00:00

I'm sorry I can't reproduce your problem with this code snippet, could you please show a minimal, reproducible sample without private information?
David Lowndes 4,711 Reputation points

2021-06-15T08:32:00.793+00:00

Serial communication through a COM port is not normally related to MS "COM" (Component Object Model), so I don't know why you're showing code calling CoInitialize.
Sai Prashanth Josyula 1 Reputation point

2021-06-15T08:34:13.717+00:00

This was the code given by the company whose device I want to control. But I am unable to get the desired output due to the exception.
Cheers
Prashanth
David Lowndes 4,711 Reputation points

2021-06-15T08:36:51.943+00:00

Aha, so they've supplied you with a COM object to talk to their device?
In that case I can only suggest that you get back to them.

Sai Prashanth Josyula 1

Code Snippet:

    HRESULT hr = CoInitialize(NULL);



    // Create the interface pointers.
    IComMotorCommandsPtr motor1(__uuidof(ComMotorCommands));
    IComMotorCommandsPtr motor2(__uuidof(ComMotorCommands));
    printf("ssss");
    long lResult = 0;
    VARIANT_BOOL bResult = false;

    BSTR port1 = SysAllocString(L"COM3");
    BSTR port2 = SysAllocString(L"COM3");


    // Set comm settings for motor 1
    motor1->put_SelectedPort(port1);
    motor1->put_Baudrate(115200);
// Code goes on and ends at 

    CoUninitialize();
    return 0;
}

is this useful for you to verify what error is popping up.

Cheers
Prashanth

Sai Prashanth Josyula 1 Reputation point

2021-06-15T08:39:40.37+00:00

Thank you David, I have contacted them first but no support was offered for this issue. So I have reached out to the community thinking the issue is mostly with declaration of
HRESULT.

Cheers
Prashanth
David Lowndes 4,711 Reputation points

2021-06-15T08:40:12.057+00:00

Anyone would need to have installed the 3'rd party component, so it's not much use.
Sai Prashanth Josyula 1 Reputation point

2021-06-15T08:41:06.537+00:00

Thank you!
:)
Song Zhu - MSFT 906 Reputation points

2021-06-15T09:35:56.87+00:00

This code snippet cannot help reproduce the problem, perhaps the problem is related to your third-party component.

RLWA32 44,951

You may be able to get some useful information about the exception by using the following -

        try
        {
            //Insert your code here
        }
        catch (_com_error& e)
        {
            _tprintf_s(_T("Com error was \"%s\", HRESULT 0x%X\n"), e.ErrorMessage(), e.Error());
        }
    }

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_com_error at memory location 0x00BCF818 due to HRESULT initialization

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