Siemens S7-300 Configuration Manual page 207

Using the gateway
If the CP you are checking can only be accessed via a gateway, you will need to select this
specifically and specify its node address on the local network.
You also specify the S7 subnet ID of the destination network.
The subnet ID is made up of two numbers separated by a hyphen:
● One number for the project
● One number for the subnet
You can check the subnet ID in the Object Properties of the subnet in the STEP 7 project.
The subnet ID is also printed out when you print the network configuration.
You will find examples here:
Example - case a: Using a gateway - one gateway
Figure 12-3 Example of the parameter settings for the online path with one gateway
Example - case b: Using a gateway (several gateways)
If the CP to be diagnosed needs to be accessible via more than one gateway, only the first
gateway needs to be specified.
The routing via the other gateways is determined automatically.
Configuring and commissioning S7 CPs for Industrial Ethernet
Configuration Manual, 09/2013, C79000-G8976-C182-13
STEP 7 special diagnostics
12.3 Starting diagnostics
207