PROFINET Communication Protocol

PROFINET® is widely used by major industrial equipment manufacturers such as Siemens and GE. It has three different classes:

• PROFINET Class A provides access to a PROFIBUS network through proxy, bridging Ethernet and PROFIBUS with a remote procedure calling on TCP/IP. Its cycle time is approximately 100 ms, and is primarily used for parameter data and cyclic I/O. The typical application includes infrastructure and building automation.
• PROFINET Class B, also referred as PROFINET Real-Time (PROFINET RT), introduces a softwarebased real-time approach and has reduced the cycle time to approximately 10 ms. Class B is typically used in factory automation and process automation.
• PROFINET Class C (PROFINET IRT), is Isochronous and real-time, requiring special hardware to reduce the cycle time to less than 1ms to deliver sufficient performance on the real-time industrial Ethernet for motion control operations.

PROFINET RT can be used in PLC-type applications, while PROFINET IRT is a good fit for motion applications. Branch and Star are the common topology used for PROFINET. Careful topology planning is required for PROFINET networks to achieve the required performance of the system.