Is there a limitation of 64 Devices in a PROFINET IRT-network or IRT-domain?

[Webinar_Question]

Is there a limitation of 64 Devices in a PROFINET IRT-network or IRT-domain?

[BartSimpson]

Is there a limitation of 64 Devices in a PROFINET IRT-network or IRT-domain?

Each node/device in PROFINET generates network load. Ethernet has a minimum frame length that is defined as 64 bytes. At a transmission speed of 100Mbit, you can transmit around 64 devices (with minimum frames) per millisecond and still have 50% of the Ethernet free, e.g. for parallel TCP/IP communication.
Incidentally, it makes no sense to fill the channel to 100% if you want to operate a closed control loop that requires synchronous processing of the user program. Synchronous processing is essential for motion control. Here, synchronization and repeat accuracy are much more important than a short cycle time. PROFINET has decisive advantages over other bus systems in this respect, as synchronization of less than a microsecond works not only in the laboratory but also in the field.

The 64 IRT devices per millisecond can also be significantly increased if the PROFINET ASIC used supports the DFP function (Dynamic Frame Packing, also known as PROFINET Performance Upgrade). This is the case, for example, with all ERTEC 200P-2 and ERTEC 200P-3, which have been used in numerous devices for around 8 years. With DFP, the problem of the minimum frame per participant is avoided by generating PROFINET communication by the PROFINET ASIC in a summation frame. So up to 256 PN devices with DFP can be addressed per millisecond and still 50% network bandwidth is free for TCP/IP traffic.
More about this can be found here: https://www.youtube.com/watch?v=h2tWrsGF_EQ