Siemens SIMATIC ET 200AL System Manual page 1504

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 11-10 Access to C/C++ Runtime via interface X2
Communication
Function Manual, 05/2021, A5E03735815-AJ
Routing
11.3 IP forwarding
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