EtherCAT and PROFINET are both real-time Ethernet-based fieldbuses that are used in industrial automation applications. Both protocols have 100Mbps baud rate, and use Ethernet as the base layer in the communications stack, which has around 2000 bytes per transaction.

EtherCAT is known for its high speed and low latency, which makes it ideal for applications that require fast data transfer rates and low jitter. It uses a master-slave architecture where the master device controls the communication between all slave devices. EtherCAT also supports distributed clocks which allows for precise synchronization of devices.

Some examples of applications that use EtherCAT include machine tools, robotics, packaging machines, printing machines, and semiconductor manufacturing equipment.

PROFINET on the other hand is known for its flexibility and ease of use. It supports both real-time and non-real-time communication, which makes it ideal for applications that require both types of communication. PROFINET also supports a variety of topologies such as star, line, tree, and ring.

PROFINET is used in all automation engineering areas like process automation, production, safety & isochronous motion control applications.

In summary, EtherCAT is ideal for applications that require high speed and low latency while PROFINET is ideal for applications that require flexibility and ease of use.