Virtual commissioning is testing the real control software of a machine or line against a simulated model of that machine before the physical equipment is built or installed. Logic, interlocks, sequences and fault handling are debugged at a desk instead of on the shop floor, so real commissioning becomes a check rather than a search. In German it is called virtuelle Inbetriebnahme, or VIBN, and the VDI/VDE 3693 guideline defines it and classifies it in the life cycle of a machine or plant (VDI).
This guide is for engineering managers and international teams working with German machine builders. It explains how virtual commissioning works, the three common set-ups, what published results say, what it costs in effort, and how to start on one machine without buying a large simulation suite.
What is virtual commissioning, in one picture
Imagine the PLC program on one side and a 3D model of the machine on the other. Every output the PLC writes, such as start conveyor 2 or extend cylinder Y4, moves something in the model. Every sensor in the model, such as part at station 3 or cylinder end position, becomes an input to the PLC. The program cannot tell the difference between the model and the machine. Neither, after a while, can the people testing it.
The VDI/VDE 3693 Part 1 guideline was revised in May 2025 with more detail on the basic test configurations, test methods, model types and simulation configurations, and is addressed to everyone from commissioning engineers to sales engineers and electrical planners. That breadth reflects reality: virtual commissioning changes how the whole project team works, not only the programmers.
The three set-ups: MiL, SiL and HiL
| Set-up | What runs the logic | Best for |
|---|---|---|
| Model-in-the-loop (MiL) | A model of the control logic inside the simulation tool | Early concept checks before code exists |
| Software-in-the-loop (SiL) | The real PLC program on a virtual controller such as PLCSIM Advanced or TwinCAT on a PC | Most machine builder projects |
| Hardware-in-the-loop (HiL) | The real PLC hardware connected to the simulation | Timing-critical motion, safety PLC behaviour, final checks |
Most German machine builders start with software-in-the-loop because it needs no extra hardware and fits the way programmers already work. Our step-by-step guides cover virtual commissioning with PLCSIM Advanced for S7-1500 and virtual commissioning with TwinCAT.
What the evidence says
- At Tronrud Engineering, a digital twin cut the design phase by 10% and commissioning time by 25% (ISA InTech).
- In a field study on a small PLC-controlled system with 17 sensors and 10 actuators, virtual commissioning raised software quality from 37% to 84% while cutting real commissioning time by 75% (Visual Components).
- Siemens states that its virtual commissioning service for machine tools shortens real commissioning time by up to 70% (Siemens).
Treat vendor figures as upper bounds. The consistent pattern across sources is that logic errors move from site to desk, which is where they are cheapest to fix.
Machine Builder Optima use the digital twin and virtual commissioning for modular machine developmen
Siemens Software
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Watch on YouTubeWhat virtual commissioning will not find
- Wiring faults, swapped terminals and wrong device addresses.
- Mechanical problems the model does not represent: wear, play, friction that differs from the data sheet.
- Network load and real fieldbus timing, unless you go to hardware-in-the-loop.
- Safety validation. Simulation supports it but does not replace the documented validation under EN ISO 13849.
What it costs in effort
The cost is mostly modelling time. A simple model of a station, with conveyors, sensors and actuators at the level of detail the PLC needs, takes days rather than weeks. A full line with material flow and robot paths takes longer. The trick is to model only what the control logic can see: if the PLC only knows that a part has arrived, the model does not need physics for how it got there.
A first project, step by step
- Freeze a version of the PLC program and the I/O list for the machine you have chosen.
- Build the model from CAD at the level of detail the program needs: positions, end switches, part presence, simple timing.
- Connect every PLC input and output to the model through the virtual controller.
- Write test cases from the specification, the same ones you would run at the FAT.
- Run them, log every fault, fix the program, and run them again until the list is clean.
- Take the cleaned program to the real machine and record how long commissioning takes compared with the last comparable job.
Virtual commissioning vs digital twin
A virtual commissioning model is one kind of digital twin: a behavioural twin used before the machine exists. A broader digital twin stays connected to the real machine afterwards for monitoring, maintenance and planning. Building the commissioning model properly from CAD and the I/O list is the first step to that broader twin. Our product brief on iUNI digital twins for machine builders and the ISO 23247 explainer cover the wider picture.
Where Wartens fits
Wartens builds machine and line models from your CAD data at 1:1 scale and drives them with your real or simulated PLC program, so logic, interlocks and sequences are tested before site work. We work tool-neutrally across TIA Portal, TwinCAT and CODESYS. See our digital twin and virtual commissioning service and our PLC engineering work packages.
Next step: send us the I/O list and a CAD export of one machine, and we will tell you what a first model would cover and how long it would take. Contact us.
