Hi,

for both questions: NO.

why you not change your SW to use another port insteed 102?

Regards

Christoph

Duris_I

Hello,

can I ask why you selected 102 port? I'm curious what was your idea use this port, if you can little concept about bridge.

If you want to simulate a S7 CPU then you need TCP port 102 for this, as this is the standard port for S7 communication.

The method to capture this port I'm using in Nettoplcsim some time ago. I guess Siemens has added this dependencies for this annoying service to make it complicated for other applications to use this port, e.g. for emulating a S7 CPU, as in older versions of Step7 it was possible to just stop this service, and all was running without problems.

In my opinion there is no need for this service to listen on TCP port 102 for incoming connections on a programming device. It accepts opening a TCP connection, but when someone wants to connect on ISO-On-TCP layer (for example try to connect from Step7 reachable partners), it immediately closes the connection. Open network ports without any useful reason are furthermore possible security issues.

Siemens uses as underlying protocol Iso-On-TCP which is defined in RFC1006. The RFC defines the TCP port 102 as standard port for this communication type, so usally in most client applications it's not possible to change this port. As payload inside this data of RFC1006 (or all layers above transport layer) is the S7 communication. See:

https://support.industry.siemens.com/cs/de/en/view/26171811

Some CPs especially for S7-400 series allow S7 communication without RFC1006, as ISO connection directly on ethernet layer with MAC addressing. It has less overhead than TCP and thus a little bit faster and generates less network traffic.

Hi,

Could you share how you used the library to communicate with PLCSIM?