An experimental approach to estimate real-time characteristic of PROFINET IO versus PROFIBUS DP V2

This paper investigates performances of PROFINET IO Class 1, based on Ethernet@100Mbit/s, as a replacement of PROFIBUS DP V2, based on RS485 @ 12Mbit/s, for the realization of time-critical and isochronous systems. In this work, two test systems have been built. In the first one, the same experimental setup with the same application has been implemented using PROFINET and PROFIBUS networks and a smart method has been applied to measure time-related characteristic at the application level. In the second one, two PROFINET networks realized with different vendors devices have been compared. Results show that, with currently available components, PROFINET IO Class 1 RT average performance is close to PROFIBUS DP V2 average performance, whereas PROFIBUS DP V2 applications are more deterministic with a jitter well below PROFINET IO Class 1 applications. Moreover, spread between real-time performances of PROFINET IO devices from different manufacturer is still wide, indicating a rapidly evolving situation. Key-Words: Real-time, Industrial Ethernet, Isochrony, PROFINET, PROFIBUS