PROFINET is a complex communication protocol. In some situations it may be necessary to read and interpret the telegram traffic with a protocol analyzer.

In order to be able to read in an Ethernet network, expensive coupling hardware is used, which is looped into the line or a free port in a switch is configured as a "mirror port". The mirror port sends out all telegrams of another port of the switch as a copy. A device or PC with appropriate analysis software can then run on the mirror port.

PROFINET devices usually have 2 ports for PROFINET cabling. The two ports are connected to each other by an internal 2-port switch module. If the power supply of a PROFINET device fails, communication in a network line is interrupted at this point. This problem can be avoided by using ring cabling with MRP technology.

If the power supply of a PROFINET switch fails, communication with all nodes connected to this switch is no longer possible.

This behavior is a very important difference to PROFIBUS networks!

PROFINET is based on the Ethernet standard and the PROFINET switch can be used as a managed switch in normal TCP/IP networks, especially in industrial networks. In this case the PROFINET specific functions of the PROFINET switch are not addressed.

General Ethernet functions can be read out and parameterized via the web page of the PROFINET switch.

For PROFINET and also PROFIBUS, I&M stands for "Identification and Maintenance". The I&M data contains information about the PROFINET node. These are partly from the manufacturer (order number, serial number, etc.) but can also be described by the user (location, service contact, etc.).

The I&M data of all PROFINET nodes can be read out and evaluated with standard functions in the automation network.

The PROFINET switch has corresponding I&M data sets.

The PROFINET switch is a managed switch. The IP address is necessary to be able to address the switch as an active infrastructure component. You can reach the web page of the PROFINET switch via the IP address and PROFINET participants (e.g. a CPU or a programming device) can configure the switch and read information from the switch.

In PROFINET a device name can be used for the IP address for simplification, which is then synonymous with the IP address in a project.

A PROFINET switch treats PROFINET telegrams with the highest priority and ensures that there are no telegram losses and that the jitter in the transmission remains low. This secures the PROFINET transmission and allows precise control in PROFINET systems.

A PROFINET switch supports mechanisms for neighbor detection (LLDP protocol) to detect and check the topology of the network. This ensures that the structure and network cabling of the plant are correct.

A PROFINET switch enables the device replacement of PROFINET components during operation. If a PROFINET device fails during operation, a replacement device is detected after installation based on its position in the topology (by the PROFINET neighbors) and automatically assigned its IP address and PROFINET name. Then the CPU can parameterize and restart the replacement device.

Since in automation systems often many similar devices are installed, the function "Find devices via LED display" supports the simple search for a station.

To increase the reliability of networks, PROFINET switches support the ring redundancy technology MRP (Media Redundancy Protocol).

The operation of a PROFINET network is also possible with unmanaged switches.

PROFINET is divided into conformance classes (CC). The conformance classes define meaningful functional scopes and are therefore decision criteria for system operators when using PROFINET components.

By previously defining an application in a CC, the user can make a selection of components that have clearly defined minimum properties.

For more information on the conformance classes, please refer to the PNO document "The PROFINET IO Conformance Classes - Guideline for PROFINET IO (Order No.: 7.041)".

The "BF" LED indicates logical "bus errors", e.g. that the device has not received a configuration, the configuration is faulty or no PROFINET communication is possible at all (network error).

The "SF" LED indicates "collective errors". This can be e.g. a present PROFINET diagnosis.

The PROFINET switch is "real-time capable" and supports PROFINET real-time class 2 for cyclic data exchange. PROFINET generally distinguishes between two main realtime classes: RT and IRT.

The "real-time capability" of an industrial bus system generally refers to the temporal accuracy of the cyclic IO transmission. For complex and distributed automation tasks, especially in the field of drive control, it is important that the cyclic data transmission always runs uniformly. Prolonged interruptions caused by other Ethernet traffic, such as video cameras or project transmissions, must not affect the behavior of the PROFINET IO cycle as far as possible.

PROFINET RT (Realtime) uses the standard technologies of managed switches (e.g. QoS) to always prioritize the important Ethernet telegrams of the bus communication over telegrams that are not time-critical.

PROFINET IRT (Isochronous Realtime) uses special PROFINET switches to keep the jitter and the clock of the IO cycle as accurate as possible in the network and to ensure a clock-synchronous and highly performant transmission.

The Helmholz PROFINET switch supports PROFINET RT, but not IRT.