Simulating SINAMICS Drives and Motion Control: Comparing TIA Portal, SIMIT, and MATLAB/Simulink

Simulating Siemens SINAMICS variable frequency drives (such as G120 and S120) and motion control systems involves choosing between three simulation tiers: TIA Portal built-in axis simulation ('Simulate PROFIdrive drive'), SIMIT Simulation Platform, and MATLAB/Simulink co-simulation. TIA Portal simulates PLC motion commands and technology object state machines internally; SIMIT emulates fieldbus PROFIdrive telegrams and electromechanical load dynamics in real time; and MATLAB/Simulink provides high-fidelity physical modeling of power electronics, motor electromagnetics, and mechanical resonance.

Architecture of Drive Simulation in Siemens Automation Systems

Modern virtual commissioning workflows require validating automation software prior to physical machine build and installation. For variable speed drives and multi-axis motion control (e.g., SINAMICS G120 6SL3210-1PE21-8UL0 or SINAMICS S120 6SL3040-1MA01-0AA0), engineers must simulate both software control telegrams (PROFIdrive) and physical plant mechanics.

Drive simulation spans three interdependent layers:
1. Controller Layer (PLC / Motion Logic): S7-1500 / S7-400 execution of motion control technology objects (TOs), positioning sequences, and interlocking.
2. Drive Communication Layer (PROFIdrive): Cyclic telegram exchange (Standard Telegrams 1, 2, 3, 105, 352) carrying control words (STW1), status words (ZSW1), speed setpoints, and actual encoder feedback.
3. Physical / Electrical Plant Layer: Inverter pulse-width modulation (PWM), motor torque generation, mechanical inertia, friction, backlash, and external carrier loads.

Comparison Matrix: TIA Portal vs SIMIT vs MATLAB/Simulink

The following table compares the capabilities, fidelity, and typical use cases of the three primary simulation platforms:

Simulation PlatformPrimary Scope & LevelModeling FidelityInterface to ControllerIdeal Project PhaseTIA Portal Axis SimulationTechnology Object (TO) internal loopLow (Kinematic ideal integration)Internal to PLC / PLCSIM (No bus telegrams)Early software logic testing, sequence interlocks, HMI animation.SIMIT Simulation PlatformVirtual commissioning & behavioral dynamicsMedium to High (Real-time physical equations)PROFIdrive telegrams via PLCSIM Advanced / Virtual ControllerFactory Acceptance Testing (FAT), virtual commissioning, operator training.MATLAB / SimulinkIn-depth physics, power electronics, multi-bodyVery High (Continuous differential equations)SIMIT Shared Memory, FMI/FMU co-simulation, or C++ SCL blocksAdvanced mechanical design, control loop tuning, vibration analysis.

Table 1: Comparison of drive simulation platforms in Siemens automation environments.

TIA Portal Built-in Axis Simulation Workflow

In TIA Portal (STEP 7 Professional), motion control technology objects (such as TO_SpeedAxis or TO_PositioningAxis) feature an integrated software simulation toggle:
1. In the project tree, open the Technology Object configuration.
2. Under Basic Parameters > Drive, enable the checkbox Simulation: Activate simulation.
3. When downloaded to S7-PLCSIM or physical PLC, the technology object internally integrates velocity setpoints into position feedback without addressing physical hardware addresses or generating fieldbus telegrams.
4. Benefit: Allows complete verification of motion instruction sequences (MC_Power, MC_MoveVelocity, MC_MoveAbsolute) without any external software tools.
5. Limitation: Does not test drive parameter sets, ramp function generator limits, drive fault codes, or fieldbus communication health.

Fieldbus and Behavioral Simulation Using SIMIT Simulation Platform

SIMIT Simulation Platform (6DL8913-0AK00-0AB5) acts as the virtual fieldbus partner:
* PROFIdrive Emulation: SIMIT couples to S7-PLCSIM Advanced (6ES7823-1FA03-0YA5) over virtual Ethernet. It receives PROFIdrive control words and sends realistic status words and encoder actual values.
* Drive Component Library: SIMIT includes pre-built standard drive components that model torque saturation, speed ramps, braking resistors, and mechanical friction.
* Process Coupling: SIMIT links simulated drive speed to downstream mechanical carrier models, conveyor systems, and material flow tracking in real time.

High-Fidelity Electromechanical Modeling with MATLAB/Simulink and FMI

When complex mechanical loads (such as variable mass linear carriers, crane pendulum dynamics, or flexible couplings) require high physical precision:
1. Develop the non-linear motor and mechanical model in MATLAB/Simulink.
2. Export the Simulink model as a Functional Mock-up Unit (FMU) conforming to the Functional Mock-up Interface (FMI) standard via Simulink Coder.
3. Import the FMU directly into SIMIT using the SIMIT FMI Component.
4. SIMIT executes the compiled Simulink model cyclically in real time and maps mechanical variables to PROFIdrive telegrams connected to S7-PLCSIM Advanced.
5. This architecture enables closed-loop testing of complex kinematic systems without risking mechanical hardware damage.

Verification

To verify the simulated drive environment:

Launch S7-PLCSIM Advanced and load the S7-1500 or S7-400 motion program.
Start SIMIT: confirm that the virtual PROFIdrive coupling is active and exchange telegrams are synchronizing without bus faults.
In TIA Portal, open the Technology Object Commissioning Control Panel.
Take master control and issue an MC_Power enable command: confirm that STW1.0 enables and the simulated drive reports ZSW1.0 = 1 (Ready to Run).
Command a velocity setpoint: observe acceleration curves and confirm that actual speed feedback (N_ACT) tracks setpoints according to modeled mechanical inertia.

Limitations and Operational Precautions

S7-PLCSIM standard (classic S7-300/400) does not support PLCSIM Advanced virtual communication interfaces; SIMIT coupling with PROFIdrive requires S7-PLCSIM Advanced or PCS 7 Virtual Controller.
Exporting complex Simulink models with very small integration step sizes (e.g., < 100 microseconds for inverter PWM) may cause timing overruns in real-time SIMIT co-simulation; simplify high-frequency electrical transients into behavioral mechanical equivalents.
SIMIT and PLCSIM Advanced require dedicated runtime licenses (6DL8913-0AK00-0AB5, 6ES7823-1FA03-0YA5). Always validate license requirements with an authorized Siemens distributor.

Engineer FAQ

Can I export Simulink models directly into SCL code for S7 controllers?

Yes, using Siemens Target 1500S for Simulink, you can compile Simulink models directly into SCL/C++ function blocks that execute in real time on S7-1500 Software Controllers or SIMATIC Open Controllers.

What is the difference between PLCSIM and PLCSIM Advanced?

Standard PLCSIM simulates single-threaded PLC memory and cannot communicate over external virtual network adapters. PLCSIM Advanced provides full Ethernet API access, multi-instance simulation, and supports SIMIT and co-simulation tools.