communication between S7-300<->S7-200

I am quite new in Siemens communication, so please be indulgent if my questions and problems seems to be stupid.

I have 2 CPU, 300 series (315-2DP and 313C), both of them with CP 342-5, and a CPU 224XP with EM277, in my PROFIBUS network.

CPU 315-2 DP with an independent (CP 342-5) is acting like a master for the other two.

All of them are configured properly. I also succeeded to transfer some data via DP_SEND and DP_RECV function blocks in Step7, but despite that I can’t realize how the master can recognize the slave since in DP_SEND or DP_RECV is no connection id, or something like that?

I also transferred some date via a FDL connection with AG_SEND and AG_RECV and there was a special parameter for the id of the connection.

My second problem is how to read and write data from the other slave (224XP) to/from the master. They seem to be properly configured since the led on the CP EM277 is indicating the DX mode and also in NCM Diagnostics “the slave is polled by its own master”. I think that in MicroWin I have to write/read in/from V Memory at a specific offset declared by the Master, but I don’t know exactly how to read and write. Also I have no clue how the program should look like on the master(step 7 ladder ).

So, as a conclusion, my two questions are:

1. How does the masterknow to send data to aspecific slave when using FC1 in the given configuration?

2. How can I read/write data from 200-slave to 300-master? (in step 7 and in MicroWin for slave)

Can anyone help me?

Thank you very much.

Tanks for the answer.

it was not what I needed but starting form this I found the solution, that is: the CP communicate with all slave at once and what I have to do is to make aSEND that will cover all defined links, this way the last defined slave will got its information. On the 200 side I only read the VB memory with MOVE. [:)]
I hope my explanation will help some other beginner having the same problem.

Great everything is working

Thanks for feedback.

Best regards,

Wizard

HI

This post is related to the S7-CPU317- PN/DP CP 343-1 communicating with another S7-CPU317 via Ethernet TCP. Connection is unspecified. Using AG_RECV block in OB1, and a 1500 byte array as the destination.

I can verify the AG_send of of the #1 CPU and verify the data using Wireshark, all the data is being transmitted along with a header in the beginning. The problem is that the AG_recv is not writing to the specified array on the CPU#2. It looks like the data is being written to the first array element momentarily and then changes to 00.

I can see the connection is made and can see the message count increase each time the data is sent to the CPU#2.

I tried to send data to CPU#2 with Putty but I guess the header is missing and the same result happens, the first array element changes and then back to 00.

Thank You.