How to access Instance Data Block elements (siemens S7-400) from Intouch??

[drspanda]

Dear All,

I am not having any problem in accessing bool, real, int data types from a Data Blocks in Siemens PLC....

However I am not able to access from Instance Data Block....Why it is so?

Also I am accessing by symbols not by absolute addressing...Is it possible to access by absolute address from Intouch.

OPC Server is from Siemens and OPC Link is from WW

Regards,

Rajasekhar

 

[tvey]

Here's an example using absolute addressing:

Wonderware:

Simatic Block view:

 

[drspanda]

Dear tvey,

Thanks for the reply...here are some doubts...

Is it compulsory to use absolute addressing for Instance Data Blocks? I have tried with symbolic addressing and could not get the tags in Intouch....I then looked into OPC Scout and find the quality of those tags are bad....So to solve the problem, I had created a normal data block....

Also Is it compulsory to not name the IDB's if I am going to use symbolic addressing?

Thanks,
rajasekhar.

 

[JesperMP]

"Names" and Symbolic addressing are the same.
If you havent given the IDB a name then you cannot symbolically adress the rest of the symbol.

It has to be something like this:
"MyIDB".SomeStruct.SomeMorestruct.SomeData.

You cannot do like this:
DB123.SomeStruct.SomeMorestruct.SomeData.

As to your problems with bad data in the OPC Scout, then I am guessing that the Symbols have not been updated together with changes to the FB declarations. Compile in NetPro, and update the OPC server with the compiled symbols.
When you had the bad data, did you check that the addressing of the OPC symbols was the same as the adressing in the program ?