Table of Contents


With NetToPLCSim you are able to connect your SCADA/HMI-systems via S7-communication to PLCSim over TCP/IP, and read/write data areas from your simulated PLC.

NetToPLCSim works only with PLCSim version 5.4 (and above, maybe...). The older versions of the S7ProSim COM-Object doesn't support the methods used in NetToPLCSim.

Screenshot NetToPLCSim running


Extract the Zip-Archive anywhere to your harddisk.

In the /bin folder doubleclick on NetToPLCSim.exe.
An installation is not required.

If PLCSim is running, click on the Start-Button in NetToPLCSim.

If you receive an error message that port 102 is in use, this is mostly caused by the Siemens-Service SIMATIC IEPG Help Service which comes with the Step 7 installation.

This Service, respectively the program s7oiehsx.exe, has port 102 in usage. You can stop this service temporarily (command line: net stop s7oiehsx), or deactivate it completely. I know no negative effect for Step 7 when the service is stopped (maybe there are problems if you have some Simatic Net software running).

If you want to connect to PLCSim from another computer in your network, make sure you open port 102 for incoming connections.

Supported areas

Due to limitations of the S7ProSim COM-Interface it is only possible to read/write the following data areas:

Area Read Write
Data Blocks (DB) OK OK
Flags (M) OK OK
Outputs (O) OK ---
Inputs (I) --- OK
Timer (T) --- ---
Counter (C) --- ---
Peripheral Inputs (PI) --- ---
Peripheral Outputs (PO) --- ---

Any other "special" functions like alarms/events, PLC control (Stop/Run/Timesystem etc.) are not working.

Setup of your client software

The computer on which PLCSim and NetToPLCSim is running represents your PLC.
So in your client Software (SCADA/HMI/OPC) you have set the IP address of the PLC to the IP address of the network interface of the PLCSim computer, or set the IP of your network interface to the IP your PLC will later have.

NetToPLCSim don't cares about the rack/slot specifications, and handles a max. PDU size of 960 bytes.

Comments on testing NetToPLCSim with some SCADA/HMI-Systems:

It will work with any other driver that uses S7-Communication (no configuration or programming in the PLC is needed), and uses no special functions.

How it works

NetToPLCSim uses the S7ProSim COM-Interface of PLCSim, to read/write the data out of it.
A background thread waits for connections on port 102 and handles the S7 communication (ISO on TCP).

Nettoplcsim schema

With PLCSim V5.4 SP5 came support of multiple PLC instances. NetToPLCSim connects by default to the first instance of PLCSim.