Hello people,

I have established communication between a S7-200 and a S7-300 via profibus DP using an EM277 module. The network is well configured and i´m using a 32 Bytes Out / 32 Bytes In configuration on the module. I am able to send the bytes i need, but i also need to send one Double Word variable. How can i do that ?

I thought of sending the  4 bytes of the double word separately from the S7-200, but how do i rearrange them on the S7-300 side to form the Double Word?

Other suggestions?

Thanks in advance,

Boardwalk

dchartier

Hello Boardwalk;

When using an EM 277 as a Profibus slave, you must setup a data exchange area with the S7-x00 master.

Follow point 7 in the following FAQ:

How can you communicate data between the S7-200 and the S7-300 via PROFIBUS DP?

https://support.industry.siemens.com/cs/ww/en/view/2615830

That way you create an exchange area between V addresses of the S7-200 and I/Q addresses in the S7-300.

Note that the S7-300 address mnemonics used in the FAQ are German (Axxx is for Ausgang, output, Exxx is for Eingang, input), you might be more familiar with the English mnemonics:

EB10 becomes IB10

AB10 translates to QB10

Hope this helps,

Daniel Chartier

 Hello Daniel

I know that. I am moving the bytes i want to send  to VB's in the S7-200 and receiving them in IB's in the S7-300. I am using a configuration of 32 Bytes_Out/32 Bytes_In ,  and the memory exchanged area is well configured.

Moving single bytes works fine, but if i need to move Double Words ( 4 bytes) how should i proceed? Can i use VD´s and ID's, or the module only works with single bytes at a time?

Hello,

simply cut your Double to that buffer Bytes addresses (f.ex. buffer address for your Double you need is starting VB2000) as you need, if your double is f.ex. MD1000, cut it with MOVE instruction to f.ex. MB1000 to VB2000, MB1001 to VB2001, MB1002 to VB2002 and MB1003 to VB2003. On other side PLC S7-300 you can then also MOVE to your needed memory but pay attention to right order of Bytes, f.ex. you have your Double in MD50, so f.ex. from IB20 (that first MB1000 to VB2000) to MB50, IB21 to MB51, IB22 to MB52 and IB53 to MB53. Now look to Vatch Table, give address MD50 and check if value is correct. If not, change order of Bytes with MOVE instruction. Helpful?