qt访问OPC服务端读数据的代码

以下是使用Qt访问OPC服务端读取数据的示例代码：

#include <QCoreApplication>
#include <opcda.h>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // 初始化COM库
    CoInitialize(NULL);

    // 创建OPC服务器对象
    CLSID clsid;
    HRESULT hr = CLSIDFromProgID(L"OPC.SimaticNET", &clsid);
    if (FAILED(hr)) {
        qDebug() << "Failed to get CLSID for OPC server";
        return -1;
    }

    IID iid;
    hr = IIDFromString(L"{B8C9B8A1-EDC8-11D1-85DB-080009A0C907}", &iid);
    if (FAILED(hr)) {
        qDebug() << "Failed to get IID for IOPCServer";
        return -1;
    }

    IUnknown* pUnk = NULL;
    hr = CoCreateInstance(clsid, NULL, CLSCTX_SERVER, iid, (LPVOID*)&pUnk);
    if (FAILED(hr)) {
        qDebug() << "Failed to create OPC server instance";
        return -1;
    }

    IOPCServer* pServer = NULL;
    hr = pUnk->QueryInterface(IID_IOPCServer, (LPVOID*)&pServer);
    if (FAILED(hr)) {
        qDebug() << "Failed to get IOPCServer interface";
        return -1;
    }

    // 连接OPC服务端
    DWORD dwAuthnLevel = RPC_C_AUTHN_LEVEL_NONE;
    DWORD dwImpLevel = RPC_C_IMP_LEVEL_IMPERSONATE;
    WCHAR* pszServerName = L"localhost";
    WCHAR* pszClientName = L"";
    WCHAR* pszUser = L"";
    WCHAR* pszPassword = L"";
    hr = pServer->AddGroup(L"TestGroup", TRUE, 1000, 0, NULL, NULL, dwAuthnLevel, dwImpLevel, NULL, 0, &m_hGroup, &m_hServerRate, &iid, (LPVOID*)&m_pGroup);
    if (FAILED(hr)) {
        qDebug() << "Failed to add group";
        return -1;
    }

    // 读取数据
    DWORD dwCount = 2;
    DWORD* phServer = new DWORD[dwCount];
    LPWSTR* pszItemID = new LPWSTR[dwCount];
    pszItemID[0] = L"Channel1.Device1.Tag1";
    pszItemID[1] = L"Channel1.Device1.Tag2";
    hr = m_pGroup->AddItems(dwCount, pszItemID, NULL, phServer, NULL, NULL, NULL, &iid, NULL);
    if (FAILED(hr)) {
        qDebug() << "Failed to add items to group";
        return -1;
    }

    OPCITEMSTATE* pItemState = NULL;
    hr = m_pGroup->Read(OPC_DS_DEVICE, dwCount, phServer, &pItemState, NULL, NULL);
    if (FAILED(hr)) {
        qDebug() << "Failed to read items from group";
        return -1;
    }

    for (DWORD i = 0; i < dwCount; i++) {
        qDebug() << "Item ID:" << QString::fromWCharArray(pszItemID[i]) << "Value:" << pItemState[i].vDataValue.dblVal;
    }

    // 释放资源
    if (pItemState) {
        CoTaskMemFree(pItemState);
    }

    delete[] phServer;
    delete[] pszItemID;

    if (m_pGroup) {
        m_pGroup->Release();
    }

    if (m_hGroup) {
        pServer->RemoveGroup(m_hGroup, TRUE);
    }

    if (pServer) {
        pServer->Release();
    }

    CoUninitialize();

    return a.exec();
}

需要注意的是，代码中使用了OPC.SimaticNET作为OPC服务端的ProgID，如果你使用的是其他OPC服务端，需要替换该值。另外，代码中也使用了Simatic S7-1200 PLC作为OPC服务端，读取了两个Tag的值，如果你需要读取其他Tag的值，需要替换pszItemID数组中的值。