Siemens Industry Online Support
Siemens AG
Entry type: FAQ, Entry ID: 42480718, Entry date: 04/26/2010

Which connection resources are occupied in the S7-400 CPU for communication connections and services of the Industrial Ethernet CP?

  • Entry
  • Associated product(s)

One connection resource is required in the S7-400 CPU for each of the following communication connections of the Industrial Ethernet CP:

Communication connection Service TSAP
PG communication via S7 server
  • Web diagnostics, e.g. for displaying the diagnostics buffer of the CPU
  • Set time in CPU 318
  • Applets, e.g. to read MLFB or status of the CPU
System connection via S7 server
  • FTP server (read and write access to file DBs)
  • FTP client (read and write access to file DBs)
  • Applets (read and write access to CPU data)
System connection

If the SEND / RECEIVE, FTP and Web diagnostics services are used simultaneously in the Industrial Ethernet, 3 connection resources of the S7-400 CPU are occupied.

An Industrial Ethernet CP occupies a maximum of 3 connection resources in the S7-400 CPU, i.e. maximum one connection resource for:

  • PG communication via S7 server (TSAP=0x01)
  • System connection via S7 server (TSAP=0x03)
  • System connection SEND/RECEIVE (TSAP=0x0F)

Security information
In order to protect plants, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art industrial security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about industrial security, please visit