Hello all!

For a system with two CPU's in a profibus profibus, is it possible for one CPU to access the input or output addresses of the other CPU networked via profibus?

Your response is highly appreciated.

Thanks & best regards,

z00m

Hello zoom;

If one of the CPUs is a Profibus-DP master and the other a Profibus-DP slave (master-slave cyclic comms) then you can read/write up to 244 bytes OUT/244 bytes IN from the I/O area between the two.

Look at the following sample configuration, you can replace the master and the slave with your own CPUs; the E and A addresses shown in the sample use German mnemonics. In your program you would use I and Q addresses (English mnemonics).

DP link between CPU 315-2DP (slave) and S7-400 (master) with STEP 7 V5.3

https://support.industry.siemens.com/cs/ww/en/view/6518822

If both masters are Profibus-DP masters (if for example they both have a DP network of various slaves), then you have the following option: use a DP/DP coupler between the 2 masters. The DP/DP coupler is seen by each master as a single slave, and you can exchange I/Os between the two, with the same limitations as in the master-slave cyclic comms above. See Chapter 4 of the following manual:

DP/DP Coupler

https://support.industry.siemens.com/cs/ww/en/view/1179382

You could also use PUT/GET client server comms between the 2 masters, but then you cannot access directly the I/O area of each CPU. You would have to setup connections in Netpro, and you would have to copy the I/O data to DBs for transfer between the CPUs.

See this FAQ for more details:

How do you program communication blocks FB14 'GET' and FB15 'PUT' for data exchange in the S7 program of an S7-300 CPU?

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

Hope this helps,

Daniel Chartier