Automation installations are becoming more complex, and the time needed to provide the customer with a working installation is getting shorter. Simulation environments that allow for the testing of written software outside the factory are becoming increasingly popular.

Virtual commissioning is directly related to applications for software testing in simulation environments before connecting them to the real system. However, it can take different forms depending on the scale of the project, the budget and the time allocated for implementation at the factory.

PLC Simulation

In the case of automation installations based on PLC controllers, programmers are able to program blocks for simulation inside the PLC program without creating a full simulation environment. An example of such a solution is PLC control in heavy industry – the rolling mill. Simulation written in PLC consists of two parts:

• simulation of automation devices used in installation (sensors, valves, drives);
• simulation of rolling material process – “Ghost Run” mode.

Thanks to this solution, programmers can test the manual mode in the office (the manual movements of devices) and logic behavior in automatic mode during the simulated rolling of the material.

Interestingly, the “Ghost Run” simulation is also regularly used in the factory. During the launch phase, programmers can check the operation of the line, but it can also be used after longer downtimes or retooling the production line – it allows operators to test the complete installation and avoid costly bugs that may occur during operations.

Simulation environment

In the case of more complex installations consisting of many different components (such as PLC controllers and robots), simulation environments might be useful. For this reason, virtual commissioning has found a wide range of uses in the automotive industry. This is the effect of the large scale of projects, the budget and the nature of the work, in which each downtime on the production line generates losses calculated in the hundreds of thousands of euros. Virtual commissioning is very useful during the introduction of a new model to the production line when developers work under intense time pressure and any unplanned downtime in production is unacceptable.

The virtual environment consists of a hardware component, emulating hardware and an application in which a simulation of the production line is created. The application maps the production line accurately even down to the smallest detail, based on files imported from CAD applications. The goal of virtual commissioning is to check programs written by PLC and robot programmers.

The virtual commissioning environment combines various elements of automation systems (PLC controllers, drives, robots) with the simulation logic of the devices, facilitating the simulation of the entire 3D production line.

Digital twin

In 2017, Gartner recognized the digital twins technology as one of the main strategic trends.

According to the Gartner glossary, “A digital twin is a digital representation of a real-world entity or system. The implementation of a digital twin is an encapsulated software object or model that mirrors a unique physical object, process, organization, person or other abstraction.”

Digital twin technology can help secure complex production systems using virtual commissioning. It is known also as “control system simulation”.

Using digital twin in virtual commissioning you can discover errors at an early stage of development and by minimizing risks – avoid costs related to potential downtimes in the future. This way you ensure that a machine works exactly the way it should and time to market can be significantly reduced.

Control System

The virtual commissioning technology allows for control software testing prior to commissioning. For simulation (design and tests), we should use exactly the same control system and control software as in the case of the real system. It means that for virtual commissioning we need to use the same PLC or robot controller.

Summary

The definition of virtual commissioning is associated with applications used for simulation; however, it can take different forms, from simulations written directly by programmers (mainly for programmers) to simulations in advanced test environments. Furthermore, the choice of simulation should be made based on the goal that we wish to achieve:

• code testing using a simulation written in PLC before starting at the factory to detect program errors and improve software quality;
• a simulation illustrating the capacity of the production lines – configuration of workstations in the production hall and checking the profitability of investments in new robots;
• virtual commissioning with the use of dedicated applications, taking into consideration programming and technical aspects, allowing users to check and optimize the code before working on the site.

Regardless of the method of code testing, each of the above options brings measurable benefits in terms of shortening the time needed to launch a new production line, which leads to lower costs of investment.

 

Read more: Standardization in PLC Programming.