S7 connection with unspecified CPU

Dear Experts.

I have S7-400 H CPU and S7-300 CPU, I am using STEP7 v5.6 software for both for programming.

I want to send and receive data from S7-400 CPU. So I have make s7 connection in s7300  CPU

S7-400 is existing system and s7-300 is new system. Our client dont want any shutdown and trip in syatem.

So I have make s7 connection in s7300 plc and taken unspecified CPU at net pro in s7300 

My both plcs are in same network and subnetmask

Is it possible to communicate both CPU. I am using simatic manager at both end.

Thanks & Regards 

Sandeep 

Hello Sandeep;

You can use GET/PUT functions (FB15, FB14) on the S7-300 to send and retrieve data to/from the S7-400 without any modification or programming on the S7-400.

The only limitation is the amount of bytes of data you can transfer (76 bytes both ways, on a S7-300, if I remember well). 

See the following document for guidance:

https://support.industry.siemens.com/cs/us/en/view/18610307

Hope this helps,

Daniel Chartier