I used an OPC client "https://www.kepware.com/en-us/products/kepserverex/suites/omron-suite/" or NI has an OPC client/server you could also use.
And the Network Variable Library (The NI Variable Engine Must be running via Task Manager ) functions:
SetWaitCursor(1);
status = CNVCreateSubscriber ("\\\\computer name \\PLC Tag library\\OP2000_BCR_DONE", DataCallback, StatusCallback, 0, 10000, 0, &scub);
SetWaitCursor(0);
status = CNVCreateReader ("\\\\computer name\\PLC Tag library\\OP2000_BCR_DONE", StatusCallback, 0, 5000, 0, &newhand);
Delay(0.2);
CNVDispose (scub);
///----------------------------------------------------------------------------
/// HIFN Network Variable Data Callback - called whenever the data is updated.
/// HIFN NOTE: This callback is called on a worker thread and not the main thread.
/// HIPAR handle/Handle of the Network Variable connection
/// HIPAR data/Handle of the new Network Variable data
/// HIPAR callbackData/User specified callback data
///----------------------------------------------------------------------------
static void CVICALLBACK DataCallback (void * handle, CNVData data,
void * callbackData)
{
unsigned int nDims;
CNVDataType type;
char *mydata = malloc(30);
int status = FAILURE;
CNVGetDataType (data, &type, &nDims); //mydata machine_msg
status = CNVGetScalarDataValue (data, CNVString, &mydata);
sprintf(machine_msg,"%s", mydata);
CNVDisposeData (data);
}
///----------------------------------------------------------------------------
/// HIFN Network Variable Status Callback called whenever connection status changes.
/// HIFN NOTE: This callback is called on a worker thread and not the main thread.
/// HIPAR handle/Handle of the Network Variable connection
/// HIPAR status/The new status of the Network Variable connection
/// HIPAR error/The error, if any, in the Network Variable connection
/// HIPAR callbackData/User specified callback data
///----------------------------------------------------------------------------
static void CVICALLBACK StatusCallback (void * handle,
CNVConnectionStatus status, int error, void * callbackData)
{
if (error < 0)
{
puts("\nERROR...");
}
else
{
switch (status)
{
case CNVConnecting:
puts("\nConnecting...");
break;
case CNVConnected:
puts("\nConnected");
break;
case CNVDisconnected:
puts("\nDisconnected!!!");
break;
}
}
}
