Simulating systems in real time means that the simulation is synchronized with real time. Accordingly, the simulation must simulate the system at least as fast as it would need in real time. If the simulation is faster than real time, it must be artificially delayed.

The advantage of real-time simulations is that they are able to interact with real components, since the simulation can react in real-time to external influences, e.g. control units, and the connected devices receive a reaction from the simulation in the same time, as they would from a real system.

In principle, any platform that is powerful enough to run the simulation in real time can be used to simulate systems in real time. When communicating with connected hardware, however, it must be noted that delays occur due to the communication path, which does not exist in reality. In order to keep the delays as small as possible, hardware specially designed for real-time simulation is required.

In the PHILSLAB, an OP5707XG from OPAL-RT is used for real-time simulation, which can communicate with the connected hardware via various interfaces and protocols. Highly specialized FPGAs are used for the interaction between the simulation and the respective interface, which convert the simulated signals into real signals with delay times in the microsecond range and vice versa, read in the real signals.

Furthermore, various programmable logic controllers from Bachmann are used for real-time simulation of smaller systems. These are also equipped with various interfaces and can thus connect a simulation with real hardware.