我对使用PLC完全不熟悉，但我有一个项目需要从OPC客户端服务器获取数据，然后将其发送到Access数据库表。减去OPCWriteGroupItems的大部分代码来自其他人。我只是将从OPCReadGroupItems获取的数据传输到我的函数OPCWriteGroupItems中的适当变量。我只想获取读入变量的值。谢谢。 F.Y.I. 我知道我的查询语句需要调整，以便它能正确读取变量，但这是我正在处理的另一个问题。这是一个更紧迫的问题。
以下是我提到的两个功能：
//---------------------------------------------------------
// Read items from an OPC Group
//---------------------------------------------------------
OPCStat OPCReadGroupItems (int iGrp, struct Var_Stru v[] )
{
HRESULT r1;
HRESULT *hr;
OPCITEMSTATE *is;
int iItem;
OPCStat RetVal=OPCSuccess;
if (pGRPTagSIO[iGrp]) {
if (bOPCDebug) printf("Reading data .... \n");
r1 = pGRPTagSIO[iGrp]->Read(OPC_DS_CACHE,
OPCDataGroup[iGrp].iNumItems,
OPCDataGroup[iGrp].hItem,
&is,
&hr);
if (FAILED(r1)) {
printf("Error from Read(%lx)\n", r1);
RetVal = OPCError;
} else {
// if the read worked then copy results to the v structure based on type
for (iItem=0;iItem<OPCDataGroup[iGrp].iNumItems;iItem++ ) {
//printf("Read item= %d, hr= %lx, Quality= %2x", iItem, hr[iItem], is[iItem].wQuality);
if(!FAILED(hr[iItem])) {
// printf("%d", is[iItem].vDataValue.vt);
//printf("%d", iGrp);
switch(is[iItem].vDataValue.vt) {
case VT_I2: // 2
v[iItem].iVal = is[iItem].vDataValue.iVal;
break;
case VT_I4: // 3
v[iItem].lVal = is[iItem].vDataValue.lVal;
break;
case VT_R4: // 4
// printf("Z");
v[iItem].fVal = is[iItem].vDataValue.fltVal;
break;
case VT_R8: // 5
v[iItem].dblVal = is[iItem].vDataValue.dblVal;
break;
case VT_BOOL: // 11
v[iItem].bVal = is[iItem].vDataValue.boolVal;
break;
case VT_UI1: // 11
printf("TEST");
sprintf(v[iItem].cVal, "%s", is[iItem].vDataValue.cVal);
printf("%s", v[iItem].cVal);
printf("%c", v[iItem].cVal);
break;
case VT_BSTR: // 8
// printf("TEST");
sprintf(v[iItem].cVal,"%-.*ls", kOPCStringSize,is[iItem].vDataValue.bstrVal );
//printf("\n STRING STRING %s \n", v[iItem].cVal);
break;
default:
break;
}
}
if(iGrp >= 0 && iGrp <=)
{
stuct_double[iGrp-1][iItem] = v[iItem].dblVal;
// printf("group %d ", iGrp);
// printf("Tag %i: %10.2f\n", iItem, root_plc[iItem]);
}
if(iGrp > 0 && iGrp <= 44)
{
struc_floats[iGrp-1][iItem] = v[iItem].fVal;
//printf("GROUP %d ", iGrp);
//printf("Tag %i: %10.2f\n", iItem, struc_floats[iGrp-1][iItem]);
}
else
{
printf("Error reading data item %d\n", iItem);
//RetVal=OPCError; //Make not as severe -- rjf 06/03/02
RetVal=OPCWarning;
//break; //Escape the for-loop -- rjf- 5/13/02
}
*/
pIMalloc->Free(hr);
for (iItem=0;iItem<OPCDataGroup[iGrp].iNumItems;iItem)
{
VariantClear($is[iItem].vdatavalue)
}
pIMalloc->Free(is);
}
}
else{
RetVal=OPCError;
}
return (RetVal);
}
//-----------------------------------------
// Write items contained in an OPC Group
//-----------------------------------------
OPCStat OPCWriteGroupItems (int iGrp, struct Var_Stru vOut[] )
{
/* Data Access Method used in this sample */
const char* DAM = "Direct ODBC";
/* Connection string for Direct ODBC */
char szDSN[256] = "DSN=Gas_Meter_check;";
HRESULT r1,r2;
HRESULT *hr;
VARIANT v[nMaxOPCItems];
int iItem;
OPCStat RetVal=OPCSuccess;
if (pGRPTagSIO[iGrp]) {
for (iItem=0;iItem<OPCDataGroup[iGrp].iNumItems;iItem++) {
v[iItem].vt = OPCDataGroup[iGrp].iType;
switch(OPCDataGroup[iGrp].iType) {
case VT_I2: // 2
v[iItem].iVal = vOut[iItem].iVal;
break;
case VT_I4: // 3
v[iItem].lVal = vOut[iItem].lVal;
break;
case VT_R4: // 4
v[iItem].fltVal = vOut[iItem].fVal;
break;
case VT_R8: // 5
v[iItem].dblVal = vOut[iItem].dblVal;
HENV hEnv; HDBC hDbc;
/* ODBC API return status */ RETCODE rc;
int iConnStrLength2Ptr;
char szConnStrOut[256];
int i= 0;
char datetime[256];
double HMCO=1.0;
double HMR,HMT;
unsigned char* InsertQuery = "INSERT INTO Data ( [Date / Time], [Hot Strip Mill rate], [Hot Strip Mill Comm Okay], [Hot Strip Mill Total] ) SELECT #datetime# AS Expr1, HMR AS Expr2, 1 AS Expr3, HMCO AS Expr4, HMT AS Expr5;";
SQLCHAR chval1[128], chval2[128], colName[128];
int ret1;
int ret2;
/* Number of rows and columns in result set */
SQLINTEGER rowCount = 0;
SQLSMALLINT fieldCount = 0, currentField = 0;
HSTMT hStmt;
/* Allocate an environment handle */
rc = SQLAllocEnv(&hEnv);
/* Allocate a connection handle */
rc = SQLAllocConnect(hEnv, &hDbc);
/* Connect to the TakeCharge database */
rc = SQLDriverConnect(hDbc, NULL, (unsigned char*)szDSN,
SQL_NTS, (unsigned char*)szConnStrOut,
255, (SQLSMALLINT*)&iConnStrLength2Ptr, SQL_DRIVER_NOPROMPT);
if (SQL_SUCCEEDED(rc))
{
printf("%s: Successfully connected to database. Data source name: \n %s\n",
DAM, szConnStrOut);
/* Prepare SQL query */
printf("%s: SQL InsertQuery:\n %s\n", DAM, InsertQuery);
rc = SQLAllocStmt(hDbc,&hStmt);
rc = SQLPrepare(hStmt, InsertQuery, SQL_NTS);
/* Excecute the query and create a record set */
rc = SQLExecute(hStmt);
if (SQL_SUCCEEDED(rc))
{
printf("Executing query...");
printf("\n");
}
while (SQL_SUCCEEDED(rc))
{
printf(" insert passed\n");
rc = SQLFetch(hStmt);
rowCount++;
};
}
else
{
printf("%s: Couldn't connect to %s.\n", DAM, szDSN);
}
/* Disconnect*/
SQLDisconnect(hDbc);
printf("%s: Cleanup. Done.\n", DAM);
break;
case VT_BOOL: // 11
v[iItem].bVal = vOut[iItem].bVal;
break;
case VT_BSTR: // 8
// printf(" In Message value (VT_BSTR) = %s \n",vOut[iItem].cVal );
r2 = LPTSTR_to_BSTR ( &v[iItem].bstrVal , vOut[iItem].cVal);
if ( r2 != S_OK ) {
printf ("error in memory \n");
RetVal = OPCError;
}
// printf(" Write Msg value(VT_BSTR) = %ls \n", v[iItem].bstrVal );
report(0,0,0, "STRINGS data %s",vOut[iItem].cVal);
break;
default:
printf(" value(unknown type:%d) ", OPCDataGroup[iGrp].iType );
RetVal = OPCError;
break;
}
//if (bOPCDebug) DumpVariant(OPCDataGroup[iGrp].cTagNames[iItem], &v[iItem]);
}
r1 = pGRPTagSIO[iGrp]->Write(
OPCDataGroup[iGrp].iNumItems,
OPCDataGroup[iGrp].hItem,
v,
&hr);
if (FAILED(r1))
{
printf("Error from Write(%lx)\n", r1);
RetVal = OPCError;
} else {
//if (bOPCDebug) printf("Successful Write ... \n");
// Clear the Variant
for (iItem=0;iItem<OPCDataGroup[iGrp].iNumItems;iItem++) {
VariantClear(&v[iItem]);
}
pIMalloc->Free(hr);
}
} else {
RetVal = OPCError;
}
return(RetVal);
}
答案 0 :(得分：1)
C / C ++不是我的第一语言，我不熟悉您的特定OPC库（有很多），但根据我对代码的理解，您正在阅读某种变量变量，并使用案例您确定其类型的语句并将其存储到 v [iItem] 的适当属性中。您在该循环中对该组中的所有标记重复此操作。必须有一些属性告诉您刚刚阅读的标记的名称，您可以使用它来解决问题。
例如，如果您正在读取的当前标记是单浮点类型，则将执行此案例部分：
case VT_R4:
v[iItem].fVal = is[iItem].vDataValue.fltVal;
break;
所以 v [iItem] .fVal 包含OPC标签的4字节单浮点值。如果您正在读取的当前标记是双浮点类型，则将执行此案例部分：
case VT_R8:
v[iItem].dblVal = is[iItem].vDataValue.dblVal;
break;
和 v [iItem] .dblVal 包含OPC标记的8字节双浮点值。我想你得到的照片。
你应该花些时间在http://www.opcfoundation.org上的 OPC DA 教程。