SIMIT Simulation Coupling with PLCSIM: S7-400 (PCS 7) vs S7-1500 (TIA Portal) Compatibility and Setup

In SIMIT Simulation Platform (V9.0, V10.x), the standard 'PLCSIM Coupling' is architected specifically for classic Step 7 / PCS 7 S7-300 and S7-400 controllers communicating with classic S7-PLCSIM (s7wsvapx.exe). When attempting to simulate an S7-1500 controller programmed in TIA Portal, the classic PLCSIM coupling fails with the error 'The PLCSIM program is not running. Please start PLCSIM first'. Basic TIA PLCSIM (Siemens.Simatic.PlcSim.Compact.exe) does not expose the required inter-process COM interface; co-simulating an S7-1500 controller with SIMIT requires S7-PLCSIM Advanced using the dedicated 'PLCSIM Advanced Coupling' in SIMIT, accompanied by assigning the Windows user account to the 'Siemens TIA Openness' local security group.

Architecture of SIMIT Virtual Controller and Simulator Couplings

The SIMIT Simulation Platform enables comprehensive virtual commissioning of industrial plants. It models physical field dynamics (valves, motors, flow, temperature) and bridges this behavioral model to the automation controller software.

To exchange process inputs and outputs cyclically, SIMIT provides specialized Couplings. For software-in-the-loop testing without physical PLCs, engineers connect SIMIT to software emulators. However, because Siemens maintains two distinct controller engineering lines—the classic Step 7 / PCS 7 platform (S7-300/400) and the TIA Portal platform (S7-1200/1500)—the underlying simulation engines and coupling protocols differ fundamentally.

Classic S7-PLCSIM (S7-400/PCS 7) vs S7-PLCSIM Advanced (S7-1500)

The differences between the two simulation ecosystems include:

Classic S7-PLCSIM (V5.x): Process name s7wsvapx.exe. Developed for S7-300 and S7-400 / CPU 410 in PCS 7. Exposes standard COM automation interfaces (S7PROSIM) that SIMIT's 'PLCSIM' coupling hooks into natively.
Basic TIA S7-PLCSIM (V14 - V18): Process name Siemens.Simatic.PlcSim.Compact.exe. A lightweight GUI emulator designed purely for basic ladder testing. It does NOT support API-based external data injection or co-simulation.
S7-PLCSIM Advanced: A high-performance virtual controller engine that runs S7-1500 firmware in a virtualized container, exposing high-speed shared-memory APIs for external tools like SIMIT.

Root Cause Analysis: Why Classic PLCSIM Coupling Fails with TIA Portal

When a user configures a SIMIT project with a standard 'PLCSIM' coupling and launches TIA S7-PLCSIM V14, SIMIT halts with 'PLCSIM is not running':

Process Polling Failure: SIMIT's classic coupling specifically searches for the running process s7wsvapx.exe. Finding only the TIA executable, it assumes PLCSIM has not been started.
Unassigned Instance Trap: If the coupling's Instance Number is set to 'Unassigned' in SIMIT, SIMIT turns orange/grey and disables all signal streaming.
Missing Windows Security Group: TIA Openness and PLCSIM Advanced communication requires the active Windows user to be an explicit member of the Siemens TIA Openness Windows user group.

Configuring PLCSIM Advanced Coupling and Windows User Groups

To correctly configure co-simulation for S7-1500 or modern mixed architectures:

Install S7-PLCSIM Advanced: Install S7-PLCSIM Advanced (e.g., V2.0, V3.0, or V4.0) on the engineering workstation.
Configure Windows User Rights:
- Open Computer Management > Local Users and Groups > Groups.
- Locate the group Siemens TIA Openness.
- Add your active Windows user account. Log off and log back on to apply changes.
Configure SIMIT Coupling:
- In SIMIT, delete the legacy 'PLCSIM' coupling.
- Add a new PLCSIM Advanced Coupling.
- In the coupling properties, specify the instance name (e.g., Instance_1) and select interface PLCSIM Virtual Ethernet Adapter or Softbus.
Start Simulation: Start PLCSIM Advanced first, download the TIA Portal hardware and program, and then start the SIMIT simulation.

Comparison of SIMIT Controller Simulation Coupling Profiles

The following table compares the different simulation coupling types supported by SIMIT:

Coupling Type in SIMITSupported PLC FamiliesRequired Simulation SoftwareCommunication MethodHigh-Speed Co-SimulationStandard PLCSIM CouplingS7-300, S7-400, CPU 410 (PCS 7)Classic S7-PLCSIM V5.4 / V5.6COM (S7PROSIM API)Moderate (< 50 ms)PLCSIM Advanced CouplingS7-1500, ET 200SP CPUS7-PLCSIM Advanced V2+High-Speed Shared MemoryExtremely Fast (< 1 ms)SIMIT Virtual Controller (VC)S7-300, S7-400H, CPU 410-5HIntegrated SIMIT VC EngineDirect execution inside SIMITReal-time synchronizedBasic TIA PLCSIMNone (Not Supported)Standard TIA PLCSIMN/A (No external API)Unsupported

Verification

Verify proper co-simulation between SIMIT and the target controller emulator:
1. Start S7-PLCSIM (or PLCSIM Advanced); confirm that the virtual CPU status indicates RUN with a green LED.
2. In SIMIT, click the Start Simulation button (play icon); confirm that the bottom status bar turns solid green and displays 'Simulation running'.
3. Toggle a digital input switch on a SIMIT process graphic; verify that the corresponding input bit (%I0.0) asserts instantly in the controller program.
4. Command a motor run output in the controller program; verify that the SIMIT virtual feedback signal updates within one simulation cycle.

Limitations and Operational Precautions

Never attempt to run Classic PLCSIM V5.x and TIA PLCSIM simultaneously with the same SIMIT coupling; instances will clash over local IPC memory channels. When running high-density co-simulation models with thousands of analog I/O points and hydraulic loops, allocate at least 4 dedicated CPU cores and 16 GB of RAM to the simulation host to prevent clock skew between the SIMIT physics engine and the virtual controller.

Engineer FAQ

Can standard TIA Portal PLCSIM connect to SIMIT?

No. Standard TIA PLCSIM does not include external API interfaces. Co-simulating TIA Portal S7-1500 controllers with SIMIT strictly requires S7-PLCSIM Advanced.

Why does SIMIT work out-of-the-box with PCS 7 S7-400 PLCSIM?

Because PCS 7 utilizes Classic S7-PLCSIM V5.x (s7wsvapx.exe), which natively includes the S7PROSIM COM interface that SIMIT's standard PLCSIM coupling was engineered to use.