Is an Industrial Ethernet communication protocol suite, defined by IEC 61158 and IEC 61784 for use in automation systems. PROFINET IO uses three different communication channels for data transfer. The standard TCP/IP channel is used for configuration, large file transfers (e.g. PLC programs), and unscheduled read/write operations. I/O Channel Diagnostics are transferred over this channel.
The RT or Real Time channel is used for scheduled data transfer, I/O and alarm information. RT communications bypass the standard TCP/IP interface to expedite the data exchange with Programmable Controllers. I/O Channel Alarms are transferred over this channel. It uses the Fieldbus Data Link for Layer 2 of the OSI model, like Profibus DP. This ensures compatibility between the Profibus protocols.
The third channel, Isochronous Real Time (IRT) is the very high speed channel used for Motion Control applications. IRT is implemented using a custom ASIC.