FAQ: Virtual Commissioning & Digital Twin
The two technical terms ‘virtual commissioning’ and ‘digital twin’ are on everyone’s lips across many industrial sectors. Nevertheless, there are also many uncertainties and inaccuracies being bandied about at trade fairs and in the corridors of companies. With our Frequently submitted Questions (FAQ) We would like to make a small contribution to helping you find reliable answers to the issues that concern us at WinMOD – and many of you – on a daily basis.
Topic: Virtual Commissioning (VC)
What is the abbreviation for ‘virtual commissioning’?
The common abbreviation for virtual commissioning is VC. Internationally and in technical data sheets, you will often also find the abbreviation VC for Virtual Commissioning. Both have become established as standard terms in mechanical and plant engineering.
What does ‘virtual commissioning’ mean? / What is ‘virtual commissioning’? / What is ‘virtual commissioning’?
Virtual commissioning refers to the testing and validation of a plant’s control system using a digital model. This enables PLC programmes, robot programmes and other control functions, as well as their interaction with the virtual plant, to be tested and optimised before the actual plant is fully assembled and commissioned.
How does a virtual commissioning work? / What is the process for virtual commissioning?
Virtual commissioning takes place as part of a clearly defined three-step process:
First, the actual plant is modelled digitally. The PLC is then connected to the control software so that plant processes can be simulated and tested virtually. Errors and areas for optimisation are identified and rectified at an early stage, before the control system is deployed on the actual plant.
What is Software-in-the-Loop (SiL)?
A virtual commissioning process carried out entirely at the software level is known as Software-in-the-Loop (SiL). In these tests, no physical components are used at all:
- The Plant model:Exists as a virtual behavioural model in WinMOD.
- The Control:Runs as an emulated software PLC on the same PC or a networked PC.
- Yours, Advantage:An extremely flexible, location-independent and scalable test architecture that requires no hardware whatsoever.
Why virtual commissioning? / What are the benefits of virtual commissioning?
Virtual commissioning offers a Time saved from to to 75 % during actual commissioning on site. The key benefits of using WinMOD include:
- Early Error detection:Software bugs are now being identified and rectified in a relaxed atmosphere in the office, rather than under time pressure on the building site.
- Solid Cost reduction:They help you avoid unexpected delays for customers, save on expensive travel costs for last-minute call-outs and eliminate the risk of hardware damage caused by collisions.
- Higher Software quality:By enabling the straightforward simulation of fault scenarios, the control code achieves a level of maturity that could not possibly be tested on real machines for safety reasons.
What is the business case for virtual commissioning in the automation industry?
The economic justification (the ROI) for virtual commissioning is best explained by the principle of radical risk minimisation. Any error that is only noticed once work has begun on the customer’s actual construction site costs many times more than it would have cost to rectify it in the office. In practice, the investment in a WinMOD licence and the time spent building the model often pay for themselves simply by preventing the very first system crash.
When considering cost-effectiveness from a holistic perspective, the benefits are not limited solely to reducing travel and accommodation costs. Here is a detailed breakdown of the risks that are effectively mitigated by WinMOD:
| Risk factor | The real problem on the building site | The cost-effective solution through virtual commissioning (e.g. using WinMOD) |
| Test risks (hardware) | PLC code that has not been adequately tested on actual machines poses a serious fire hazard. Faulty control logic can, for example, lead to unexpected movements, causing parts of the system or workpieces to collide with one another and result in damage. | Free collisions: Nothing breaks in the digital twin. You can test critical limit conditions and emergency stop sequences in a completely non-destructive manner, as often as you like. |
| Human risks | Commissioning engineers often work on site under extreme time pressure, whilst suffering from jet lag or construction site noise. Fatigue inevitably leads to a higher error rate. Furthermore, working alongside machines weighing several tonnes that have not yet been tested poses an enormous physical safety risk to staff. | Stress-free engineering: The most critical and error-prone part of the work – debugging the code – is moved to a quiet, safe and ergonomically designed office environment. This protects staff health and helps retain skilled workers. |
| Hidden sources of error | Modern systems consist of tens of thousands of I/O signals. A simple transposition in the sensor configuration within the E-CAD software may go unnoticed mechanically, but leads to a system crash in the software. On site, the nerve-wracking search for a needle in a haystack then begins. | Maximum transparency: WinMOD visualises signals and logic in real time. Signal errors are immediately apparent thanks to the 3D simulation and can be rectified with just a few clicks, before the first actual cable is laid. |
| Financial risks | Delays in delivery can prove extremely costly in plant engineering. In the event of delays, contractual penalties can very quickly eat into the entire project margin. Actual commissioning often acts as a bottleneck, as it can only take place at the end of the project chain. | Reliability of delivery: Through Concurrent Engineering Programmers no longer have to wait until the mechanical components have been fully assembled. The software is tested in parallel, which drastically reduces lead times and ensures the delivery date is met. |
In summary: From a commercial perspective, virtual commissioning is not merely „simulation software“, but the most effective insurance policy against contractual penalties, hardware damage and staff burnout that a plant manufacturer can take out today.
What benefits does virtual commissioning offer users?
Virtual commissioning opens up entirely new, agile ways of working and offers highly specific benefits depending on the area of responsibility within the company. Thanks in particular to concurrent engineering – that is, the parallel development of mechanical, electrical and Automation systems – specialist departments no longer have to wait for one another.
The following overview sets out the specific utilization of the WinMOD platform for the three main target groups within the organisation:
| Target audience | Specific utilization of VC (WinMOD) |
Users in the Automation (SPS-Programmer) | Stress-free Engineering: Complex control code can be tested at leisure in the office. Faulty control logic can, for example, lead to unexpected movements, causing parts of the plant or workpieces to collide with one another and result in damage. |
| Project Manager for the facilities | Planning certainty: Significant risk reduction throughout the project. As software testing begins in parallel with mechanical assembly, lead times are drastically reduced. This ensures that factory acceptance tests can be planned and carried out on schedule. |
| Management | Cost control & ROI: Avoiding significant costs arising from errors and contractual penalties caused by delivery delays. In addition, there is a significant reduction in travel and commissioning costs, as well as the strategic advantage of a higher standard of delivery to the end customer. |
In addition, future plant operators benefit from being able to undergo risk-free training on the virtual model even before the plant is physically completed.
Topic: Digital Twin
What is a digital twin? / What is a digital twin, explained simply?
A digital twin is the exact virtual replica of a real-world object, system or plant. Not only does it look exactly like the original, but it also accurately replicates its behaviour in systems such as WinMOD. When you press a button in the real world, something happens – the twin does exactly the same thing digitally, which makes it a central component of Industry 4.0.
What does a digital twin do?
A digital twin exchanges data in real time with its real-world environment or the connected control system. For example, it receives control commands from the PLC (such as „Motor on“) and immediately sends the corresponding feedback (such as „Light barrier interrupted“) back via the WinMOD real-time simulation, thereby creating a closed-loop control system.
What is an industrial digital twin? / What is a digital twin in manufacturing?
An industrial digital twin in production is the virtual representation of an entire production line or factory. This is no longer just about a single machine, but about the flow of materials, cycle times and the flawless interaction of dozens of plant components and control systems. With WinMOD, this complex plant environment can be modelled independently of the manufacturer and tested reliably in advance.
What is an example of a digital twin?
To illustrate how a digital twin works, let us consider two typical industrial scenarios in which the WinMOD software generates a dynamic, intelligent behavioural model from static design data:
Example 1: Intralogistics (automated parcel sorting system)
Imagine a new distribution centre with hundreds of conveyor belts, junctions and barcode scanners. Before the building is even constructed, it is created as a digital twin on a computer.
The scenario: The WinMOD model simulates a high-load scenario – 100 parcels per minute pass along the virtual conveyor belt.
The interaction: A virtual package passes through a simulated light barrier. The twin reports the signal „Light barrier 1 interrupted“ to the control system (PLC) in real time.
The reaction: The PLC processes the signal and issues the command „Extend the pneumatic cylinder for the points“. In the WinMOD model, the virtual cylinder then extends and diverts the train without any faults.
Utilization (stress test): The programmer can now test what happens if a parcel becomes jammed or a sensor becomes dirty. The system’s logic is tested under extreme conditions without a real parcel falling to the floor.
Example 2: Special-purpose machinery manufacturing (complex robotic welding cell)
In automotive manufacturing, different systems often work in extremely close collaboration; for example, a higher-level Siemens PLC and a specialised KUKA robot controller.
The scenario: A turntable (controlled by the PLC) positions a car door whilst the robot arm applies the weld spots.
The interaction: The digital twin in WinMOD links the two control systems. It simulates the signals indicating when the table is in position and issues the simulated go-ahead to the robot.
Utilization (collision avoidance): What happens if the programmer has made a mistake in the code and the table starts to rotate whilst the robot arm is still performing Welding? In reality, this means metal parts colliding, weeks of downtime and tens of thousands of euros’ worth of damage. In the digital twin, the WinMOD simulation simply stops with a virtual error message – the code is corrected, and the real machine remains unscathed.
In summary:
A digital twin is not merely 3D cinema, but a bidirectional (two-way) testing tool. It responds to control commands in exactly the same way as the real-world machinery and provides the appropriate sensor feedback long before the first steel beam is bolted into place on site. This is a standard procedure which is defined, amongst other things, in the VDI 3633 series of guidelines (Simulation of Logistics and Production Systems) as best practice for modern plant design.
Is a digital twin AI?
A digital twin for automation technology is not necessarily artificial intelligence. Traditional twins used in virtual commissioning are based on hard-coded, deterministic logic – they always behave exactly according to the same rules in order to test the PLC code in a predictable manner. By analysing the data recorded in WinMOD, Data, the AI anomalies identify potential causes of faults and highlight opportunities for optimisation in plant processes.
What is a digital twin and how is it created?
A digital twin is created by intelligently consolidating existing design data. Nobody draws the twin from scratch. The creation process follows a highly efficient workflow:
- Mechanical Import: Import of geometric data from the 3D CAD system.
- Electric Import: Importing sensor and actuator lists from the E-CAD system (e.g. via EPLAN).
- Automated Behaviour generation: The WinMOD Engineering AssistantIt links this data, largely automatically, to form a functional behavioural model, which drastically reduces the amount of manual engineering work required.
What are the benefits of a digital twin?
A digital twin makes invisible software processes visible and enables design faults to be predicted. Operators and planners benefit in the long term:
- It acts as an extremely secure sandbox for engineering.
- Optimisations (e.g. increasing cycle times) can be tested without risk.
- Alterations or extensions (Retrofits) can be tested virtually without having to halt ongoing production at the plant.
What are the disadvantages of a digital twin?
The biggest challenge with a digital twin lies in its absolute dependence on data quality and in the initial set-up. The principle is that Rubbish in, rubbish out: If the underlying design drawings are out of date or incorrect, this is also reflected in the twin.
Whilst the WinMOD Engineering Assistant helps with data automation for transfer from E-CAD, lifecycle management still requires clear internal processes to ensure that the model is updated in real time when actual modifications are made to the machine.
The following table sets out the disadvantages and challenges against the enormous advantages:
| Challenges (drawbacks) | Opportunities (benefits offered by a digital twin, e.g. using WinMOD) |
| High data dependency: Incorrect CAD or E-CAD data results in an inaccurate simulation model. | Safe testing: Logical errors do not result in hardware damage, as collisions only occur virtually. |
| Initial effort: Time and resources required to create the model for the first project. | Automation: Significantly reduced modelling times for subsequent projects through the use of WinMOD macros and wizards. |
| Lifecycle management: It is essential that the twin is updated whenever a real change is made to the asset. | Ongoing optimisation: Cycle times, retrofits or updates can be tested virtually without halting actual production. |
How much does a digital twin cost?
It is not possible to put a flat rate on the cost of a digital twin, as it depends heavily on the scale and depth of the simulation. It essentially comprises two components:
The WinMOD software licence: Scales modularly depending on the number of fieldbus drivers required and the scope of the simulation environment.
The engineering effort: The time taken to link the data and build the model.
The relation: The investment starts at relatively small amounts for individual stations, but in practice it usually pays for itself as soon as the first delay in commissioning on the building site is avoided.