PROFINET IO OVERVIEW

PROFInet IO devices are typically configured by Siemens Step 7 software. Using Step 7, devices descriptions are loaded from the GSDML files. I/O configurations are mapped into the I/O tables of the Siemens IO Controller and IP addresses are assigned to each PROFInet IO device. Figure 2 graphically represents the structure of this system.

Profibus ® is a worldwide standard for transmission of process data between field level devices and programmable controllers. How can I/O data and other information travel between Profibus and PROFInet IO? At the physical level these two communication networks are completely incompatible. Profibus is at its core an RS485-based communication standard with a maximum baud rate of 12M. At the core of PROFInet is Ethernet, another worldwide standard with baud rates of 100M and beyond.

Are they at all compatible at the protocol level? Profibus is I/O driven. Data is transferred as blocks of inputs and outputs which are interpreted by agreement between the Profibus Master and the Slave. PROFInet IO is also I/O driven with data transferred in blocks of inputs and outputs. In both systems, there is a Master or IO-Controller and one or more IO devices.

Since a Profibus Master device can access all the data of the Profibus network the logical place for a communications gateway is as the Master device of the Profibus network. This is illustrated in the Figure 3 .