Communication 
  3.2 Communication services 
CPU 31xC and CPU 31x, Technical Data 
Manual, 01/2006 Edition, A5E00105475-06 
3-11 
3.2.7  Routing 
Properties 
STEP 7 V5.1 + SP4 or higher allows you to access your S7 stations on all subnets with your 
PG/PC, for example, to  
•  download user programs 
•  download a hardware configuration, or 
•  perform debugging and diagnostic functions. 
 
 
 
Note 
If you use your CPU as I-slave, the routing function is only possible when the  
DP interface is switched to active IN STEP 7, set the Test, Commission Routing check 
box on the properties dialog of the DP interface. For detailed information, refer to the 
Programming with STEP 7
 manual, or directly to the 
STEP 7 Online Help
 
 
Routing network nodes: MPI - DP 
Gateways between subnets are routed in a SIMATIC station that is equipped with interfaces 
to the respective subnets. The figure below shows CPU 1 (DP master) acting as router for 
subnets 1 and 2. 
3*
6 6
6XEQHWHJ352),%86'3
6XEQHWHJ03,
&38'3PDVWHU &38'3VODYH