Siemens SINUMERIK 840D sl TCU 30.3 Equipment Manual page 41

The following rules apply for assignment of IP addresses in the system network:
• For all NCUs and/or PCUs/IPCs, the commissioning engineer assigns fixed IP addresses in the
associated address bands, as well as appropriate computer names (host names). All other
operator components are automatically assigned an IP address by the DHCP server. Its name
is generated automatically (for MCP, MPP, HT 8), or is entered at commissioning (TCU).
• If there are multiple NCUs, IPCs and/or PCUs in the system network, depending on the boot
sequence, the system automatically specifies the DHCP server and automatically ensures
synchronization of all necessary data, so that the next time the system boots any other NCU,
IPC, or PCU could take on the role of DHCP server. However it is better to specify a DHCP
master. This is an NCU, IPC, or PCU in the system network that is available on each system
boot and which regularly takes over the task of the DHCP server and DNS server.
Synchronization of data takes place in any event so that any other NCU, IPC, or PCU can take
over this task, unless you deactivate this option in the DHCP configuration. All non-master
NCUs/IPCs/PCUs wait while the system boots for a preset time for the master to become
available.
Note
In a system network or on a boot server, i.e. on the NCU, IPC, or PCU that accommodates the
active DHCP server, a maximum of 30 operator stations may be operated simultaneously
with the TCU.
A maximum of 10 operator stations with a TCU may connect up simultaneously with the
same HMI application when powering up.
Connection to a company network
Each NCU can be connected via X130, and each PCU/IPC can be connected via "Ethernet 1" to a
company network. The company network is used to exchange operating software with servers
or to execute part-programs directly from servers in the company network. Company network
and system network should always be logically and also physically separated.
Service interface X127
The service interface X127 of the NCU is used for direct connection of a PG/PC for service
purposes. Here, access with STEP 7 to the PLC, and with NCU 7x0.3 PN also to PROFINET is
possible.
With direct connection (peer-to-peer) of a PG/PC to X127 it is absolutely necessary that the
PG is operated as a DHCP client.
TCU 30.3
Equipment Manual, 03/2023, A5E40874197B AD
Networking
6.1 System settings
41