write OPC client with LabWindows/CVI

[Marg_SZ]

Sure, I will but it will be 10 days later since I'm going on a travel. Thanks.

[Marg_SZ]

Perry, I'm back from business trip. Just now I tried using ActiveX Array functions but it still won't work. My code is as follows. Any idea what's the problem? Thanks. Margaret int AsyncReadCompleteID=0; void GroupAsyncRead(void) { char *v_item; long *v_handle; OPCAutomationObj_OPCItems ppItems; OPCAutomationObj_OPCItem ppItem; long numItems, hvalue, i; SAFEARRAY *serverHandles, *errors; status = OPCAutomation_IOPCGroupGetOPCItems(OPCGroupHandle, &Error_Info, &ppItems); status = OPCAutomation_OPCItemsGetCount(ppItems, &Error_Info, &numItems); v_handle = (long *)malloc(sizeof(long)*numItems); for(i=0; i < numItems; i++) { status = OPCAutomation_OPCItemsItem(ppItems, &Error_Info, CA_VariantInt(i+1), &ppItem); // status = OPCAutomation_OPCItemGetItemID(ppItem, &Error_Info, &v_item); //verify status = OPCAutomation_OPCItemGetServerHandle(ppItem, &Error_Info, &hvalue); v_handle[i] = hvalue; } status = CA_Array1DToSafeArray(v_handle, CAVT_LONG, numItems, &serverHandles); //AsyncRead returns a negative value to status status = OPCAutomation_IOPCGroupAsyncRead(OPCGroupHandle, &Error_Info, numItems, &serverHandles, &errors, GetTransactionID(), &cancelID); status = OPCAutomation_DIOPCGroupEventRegOnAsyncReadComplete(OPCServerHandle, ProcessGroupAsyncReadComplete, NULL, 1, &AsyncReadCompleteID); // SafeArrayDestroy(serverHandles); // SafeArrayDestroy(errors); }

[Marg_SZ]

Perry, I just come back from a business trip. I tried the ActiveX Array functions and it still won't work. My code is as follows. Any idea what's the problem? Thanks, Margaret int AsyncReadCompleteID=0; void GroupAsyncRead(void) { char *v_item; long *v_handle; OPCAutomationObj_OPCItems ppItems; OPCAutomationObj_OPCItem ppItem; long numItems, hvalue, i; SAFEARRAY *serverHandles, *errors; status = OPCAutomation_IOPCGroupGetOPCItems(OPCGroupHandle, &Error_Info, &ppItems); status = OPCAutomation_OPCItemsGetCount(ppItems, &Error_Info, &numItems); v_handle = (long *)malloc(sizeof(long)*numItems); for(i=0; i < numItems; i++) { status = OPCAutomation_OPCItemsItem(ppItems, &Error_Info, CA_VariantInt(i+1), &ppItem); // status = OPCAutomation_OPCItemGetItemID(ppItem, &Error_Info, &v_item); //verify status = OPCAutomation_OPCItemGetServerHandle(ppItem, &Error_Info, &hvalue); v_handle[i] = hvalue; } status = CA_Array1DToSafeArray(v_handle, CAVT_LONG, numItems, &serverHandles); //AsyncRead returns a negative value to status. status = OPCAutomation_IOPCGroupAsyncRead(OPCGroupHandle, &Error_Info, numItems, &serverHandles, &errors, GetTransactionID(), &cancelID); asyncReadInProgress = 1; status = OPCAutomation_DIOPCGroupEventRegOnAsyncReadComplete(OPCServerHandle, ProcessGroupAsyncReadComplete, NULL, 1, &AsyncReadCompleteID); // SafeArrayDestroy(serverHandles); // SafeArrayDestroy(errors); }

[Marg_SZ]

The code was messed up. int AsyncReadCompleteID=0; void GroupAsyncRead(void) { char *v_item; long *v_handle; OPCAutomationObj_OPCItems ppItems; OPCAutomationObj_OPCItem ppItem; long numItems, hvalue, i; SAFEARRAY *serverHandles, *errors; status = OPCAutomation_IOPCGroupGetOPCItems(OPCGroupHandle, &Error_Info, &ppItems); status = OPCAutomation_OPCItemsGetCount(ppItems, &Error_Info, &numItems); v_handle = (long *)malloc(sizeof(long)*numItems); for(i=0; i < numItems; i++) { status = OPCAutomation_OPCItemsItem(ppItems, &Error_Info, CA_VariantInt(i+1), &ppItem); // status = OPCAutomation_OPCItemGetItemID(ppItem, &Error_Info, &v_item); //verify status = OPCAutomation_OPCItemGetServerHandle(ppItem, &Error_Info, &hvalue); v_handle[i] = hvalue; } status = CA_Array1DToSafeArray(v_handle, CAVT_LONG, numItems, &serverHandles); //AsyncRead returns a negative value to status. status = OPCAutomation_IOPCGroupAsyncRead(OPCGroupHandle, &Error_Info, numItems, &serverHandles, &errors, GetTransactionID(), &cancelID); status = OPCAutomation_DIOPCGroupEventRegOnAsyncReadComplete(OPCServerHandle, ProcessGroupAsyncReadComplete, NULL, 1, &AsyncReadCompleteID); // SafeArrayDestroy(serverHandles); // SafeArrayDestroy(errors); }

[Perry_S]

Hi Marg SZ,

Could you upload a Screen shot of your code? That would be alot clearer or me. Please help me understand what you meant by "it did not work"? Did you get an error? Please let me know.

Thanks.

Perry S.

[Marg_SZ]

Perry,

Please see the attached code.

Thanks,

Margaret

[Perry_S]

Hi Marg SZ,

Here is an online help file that describe how safearrays are used in CVI.

http://zone.ni.com/reference/en-XX/help/370051H-01/cvi/cvivariants_and_safe_arrays/

Here is the help file on how to create safe arrays in CVI.

http://zone.ni.com/reference/en-XX/help/370051T-01/cvi/libref/cvica_array1dtosafearray/

Please follow these to create your safearray. Have a great day.

Perry S.