PROFINET does not require specialized switches.
PROFINET projects can employ standard Ethernet switches that satisfy the minimum requirements of 100 Mbit/s IEEE 802.3 and full-duplex transmission.
Nowadays, most off-the-shelf Ethernet switches fulfill both requirements and therefore are suitable for PROFINET.
Three terms you might encounter when choosing a switch for a PROFINET project are managed switches, unmanaged switches, and PROFINET switches. These switches have critical differences but can be employed in PROFINET projects if they support the minimum requirements (100Mbit/s / full-duplex). Here is a brief overview of each:
Unmanaged Switch
Unmanaged switches are low-cost and do not offer features for diagnostics or web interfacing. They have the minimal built-in intelligence to send incoming Ethernet frames out on the correct port.
Unmanaged switches forward traffic based on a Media Access Control (MAC) address/port allocation table. Users are not able to intervene manually in switch operation or customize diagnostic functions.
Managed Switch
A managed Ethernet switch adds intelligence that an unmanaged switch does not have.
Managed switches can offer several advantages, including user option selection based on a Command Line Interface (CLI) or Graphical User Interface (GUI), and provide diagnostics capabilities.
A managed switch provides information that can help prevent downtime and speed up troubleshooting when the line does go down. Managed switches can cost more, but the incremental cost is trivial compared to the cost of downtime.
PROFINET Switch
Managed switches can also be PROFINET devices, and such devices are commonly called PROFINET switches.
PROFINET switches have a respective General Station Description (GSD) file. The Controller recognizes them as IO devices, and the GSD file defines PROFINET-related diagnostics information. Users can set diagnostics parameters and configure them in the PROFINET engineering tool.
To find switch components, you can search online or ask your favorite vendor. Also, the PROFINET and PROFIBUS International Organization created a product finder: https://www.profibus.com/products/product-finder.
Not all existing products are listed on the product finder, but many options are available.
Learn more about PROFINET switches with our full white paper: