How to read "fetch/write connection" data in WinCC with OPC?

Dear friends

I (and some of my friends) have developed an OPC server/client to connect different devices. Now I am trying to connect S7 PLCs and read its data using SimaticNet OPC server. I successfully read data using variable service. But for read and write large amount of data I tried to use send/receive to communicate.

I read this entry: ID 21447513

Mass Data Acquisition with an OPC Client in C# based on .NET

But it isn’t what I need, because it needs some programming in S7.

So I read the entry: ID: 16649795

How do I create a Fetch/Write-connection (S5-compatible communication) to SIMATIC S7 for the SIMATIC NET-OPC Server via Ethernet with the SIMATIC NET CD 07/2001 or higher?

I did all and I saw the value of fetched buffer in OPC scout. The problem is I can not read this value in any other OPC client, even WinCC.

I made a raw tag in WinCC with this address:

SR:[ISO-on-TCP fetch]DB2,WORD0,15 ( as in OPC scout).

I made it with different types (raw, array of unsigned it,…). But this tag always returns Null.

Does anybody know how I can read this Item?

Best regards,

Mehrnoosh

Hi

I have found out how to do this!

I don't think you can do it with VBScript, but you can quite easily with C-Script.

First, define the raw tag as mentioned and define it as an array of 16-bit values, then access the data with the following (this is from a button):

#define TAG "DB100" // OPC array tag name
WORD v[15]; // data structure
BYTE *pv; // byte pointer to our data structure
int i; // loop variable

// set our bytepointer to the start of our data structure
pv = v;

// read 30 bytes(15xWORD)
GetTagRaw(TAG, pv, 30);

// loop through our data and do something with it
for (i=0; i<15; i++) {
printf("%d: %d\r\n", i, v[i]);
}

Dear Reuben

Thanks a lot for your help. Now it woks properly [:D]and it should work with all OPCs which support array of bytes.

It was very helpful. Thanks again.

Best regards,

Mehrnoosh