Siemens SIMATIC S7-1500 Function Manual page 300

IP forwarding via the interface of a CP
IP forwarding also works via the interface of a CP. For this you have to activate the "Access
to PLC via communication module" function for this CP in the CPU.
How you enable the "Access to PLC via communication module" function is described in the
online help of STEP 7.
Reaching C/C++ Runtime of the CPU 1518 4 PN/DP MFP via interfaces X1 or X2
If you activate PN/DP MFP IP forwarding for the CPU 1518 4 PN/DP, you will not only reach
devices in the IP subnet of interface X3 via interfaces X1 and X2, but also C/C++ Runtime.
From the C/C++ Runtime of the CPU 1518 4 PN/DP MFP, you reach all devices in the IP
subnets of the interfaces X1, X2 and X3.
Conditions:
● IP forwarding is enabled for the CPU 1518 4 PN/DP MFP.
● The IP address of C/C++ Runtime and the IP address of interface X3 are located in the
same IP subnet.
● The routes to the IP subnets at X1 and X2 are entered in C/C++ Runtime.
In C/C++ Runtime, enter a route with the following command: "Route add-net
<destination IP subnet> mask <subnet mask> gw <gateway>
The following figure shows a configuration in which a PC accesses the C/C++ Runtime of
CPU 1518-4 PN/DP MFP via interface X2.
Figure 10-10 Access to C/C++ Runtime via interface X2
Communication
Function Manual, 11/2019, A5E03735815-AH
Routing
10.3 IP forwarding
299