For high-performance motion control applications, such as precise coordination of hundreds of axes with microsecond precision, Profinet includes an isochronous real-time channel. Profinet RT (Profinet Real-Time) is used for closed-loop control of a system, where the control (both the set-point and feedback) for multiple devices occurs during the same sample period.
With its superior speed, DSProfinet RT allows any generic Ethernet interface to communicate with a Profinet RT network.
Certainly other Ethernet protocols in motion control today operate on a regularly occurring interval basis. So one may ask, what is special about Profinet RT. DSProfinet RT comes in stand-alone or PCI form.