siemens s7-200 to s7-300 communications

Hello,

I'm a newbie to Siemens and the site I'm working on has a bunch of different Siemens PLC's with various parts working - and others not.

My question is how does the addressing in the s7-200 translate in the s7-300?

E.g. - Data is received in the S7-200 via modbus and stored in &VB64. The S7-200 communicates on a directlink to the S7-300 using Profibus. However, the S7-300 references the data by PIW 350.

How can I verify that this is correct offline? E.g. does &VB64 = PIW 350? There are lots of similar things similar that need verification as the plant is not happy.

Thanks

Look at the hardware configuration of both PLC's. Maybe You have a Profibus card configured in the S7300, If this is so the assigned address will be shown. PIW = Peripheral Input Word which is a common addressing method used by Analogue and other specialist modules. As for VB, I cant remember what the V is (Maybe Variable) but its an internal Byte address within the S7200.

Post some more info and im sure more of the S7 Gurus will help out

Steve.

Stevo,

The S7-200 is configured as an EM277 in the Step 7 5.3 software. It has I address configured to 392 to 455 and Q address 296 to 359.

In the S7-200 program the V-memory register that contains the data starts at V64.

At present there is no offset configured in the 5.3 configuration for the V-memory - does there need to be an offset of 64 configured in the S7-300 program?

In the present configuration - is I392 = V0 and I392 + 64 = V64?

My other questions would be that I can not modify the I and Q address ranges - is there some way to do so? I can see them but they are greyed out. This is the same for the offset.

Thanks
n00b

Hi N00b,

below is a PDF Link explaining the EM277 and its various uses, Page 4,5 and especially 6 explains how the addressing areas are used.

As for your other question, Most of the cards you configure with S7, Can have the default address assigned to them changed. This is achieved in the properties dialog of the card, If this is greyed out then it probably wont let you.

http://dce.felk.cvut.cz/pss/cviceni/docs/s7200_em277.pdf

Hope this helps

Regards Stevo