Performance

The PROFINET RT data packets are transmitted to both the controller and device at a constant transmission speed. If this transmission speed cannot be maintained, then the connection is terminated by the communication watchdog “DataHoldTimer” of the PROFINET devices, even during the phase of establishing a connection.

On weak systems or systems with a poor link to the Ethernet component (SysEthernet), unstable data transmission can occur.

Then either the transmission speed has to be reduced in the Reduction ratio setting, or the communication watchdog has to be intensified. The performance of the CPU is less important than the performance of the PROFINET driver. The link of the Ethernet interface is decisive. In addition to the hardware, the software-specific link (operating system and Ethernet drivers) also plays an important role.

Examples of a possible number of connections and transmission speed:

OS	CPU	Connections * transmission speed
Windows (RTE)	Atom	50 * 1 ms
VxWorks	Power-PC	30 * 4 ms
Linux	Raspi V3	6 * 1 ms