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What Is Profinet
What is PROFINET?
PROFINET (Process Field Network) is an open industrial Ethernet standard for real-time communication between programmable logic controllers (PLCs), I/O devices, drives, and network infrastructure in factory and process automation systems. It is standardised under IEC 61158 and IEC 61784 and maintained by PROFIBUS and PROFINET International (PI), the same organisation that developed PROFIBUS. PROFINET is the most widely deployed industrial Ethernet protocol in the world, with over 60 million installed nodes across automotive manufacturing, food and beverage, pharmaceuticals, water treatment, and machine building industries.
PROFINET uses standard Ethernet hardware – the same cables, connectors, and switching technology used in office and IT networks – but adds deterministic real-time behaviour on top. It allows time-critical I/O data, diagnostic information, and standard TCP/IP traffic to coexist on the same network. A Siemens SIMATIC S7 PLC, a Beckhoff EtherCAT controller, a Phoenix Contact I/O module, and a managed switch providing network topology information can all communicate simultaneously over a single PROFINET infrastructure.
How PROFINET Works
PROFINET uses a provider-consumer communication model. An IO-Controller (typically a PLC) exchanges cyclic data with IO-Devices (field devices such as I/O modules, drives, sensors, and actuators). The controller sends outputs to devices and receives inputs from them at a fixed update rate called the cycle time, which can range from 1 millisecond for high-speed motion control down to several hundred milliseconds for slower process automation applications.
IO-Controller – the PLC or DCS that controls the automation task. Reads inputs from and writes outputs to IO-Devices. Configured in engineering tools such as Siemens TIA Portal or STEP 7.
IO-Device – a field device monitored and controlled by the IO-Controller. Each device has a GSD (General Station Description) file that describes its configuration options and data structure to the engineering tool.
IO-Supervisor – a programming or diagnostic device, such as an HMI or engineering workstation, that can read and write device parameters and access diagnostic data.
PROFINET uses three communication channels with different priorities and timing characteristics. Standard communication carries configuration, diagnostics, and non-time-critical data over TCP/IP and UDP/IP. Real-Time (RT) communication carries cyclic I/O data with deterministic timing using prioritised Ethernet frames. Isochronous Real-Time (IRT) communication, used in Class C and above, reserves dedicated bandwidth for motion control applications requiring sub-millisecond cycle times with jitter under one microsecond.
PROFINET Conformance Classes: A, B, C, and D
PROFINET defines four conformance classes (CC-A through CC-D) that describe the capabilities required of a device. Each class builds on the one below it. A CC-B device supports everything CC-A requires, plus additional capabilities. Understanding these classes explains why different Teltonika switches support different levels of PROFINET.
| Class | Protocol | Key requirements | Typical application |
|---|---|---|---|
| CC-A | RT (Real-Time) | Basic PROFINET IO communication. Cyclic and acyclic data exchange. Standard Ethernet infrastructure – no special switch capabilities required beyond reliable Ethernet switching. | Building automation, infrastructure, general I/O in environments where full network diagnostics are not required |
| CC-B | RT (Real-Time) | All CC-A functions plus: SNMP network management, LLDP topology detection, network diagnostics visible to the PLC controller. The switch must have a GSD file and be a visible PROFINET IO device. MRP ring redundancy support. | Factory automation, production lines, process automation requiring topology discovery, diagnostics, and media redundancy |
| CC-C | IRT (Isochronous Real-Time) | All CC-B functions plus: reserved bandwidth for isochronous communication, cycle times below 1 ms, jitter under 1 microsecond. Requires specialised switch hardware with hardware-based time synchronisation. | Motion control, robotics, synchronised multi-axis drives |
| CC-D | TSN (Time-Sensitive Networking) | Same capabilities as CC-C implemented using IEEE TSN mechanisms. All communication uses Ethernet Layer 2. Represents the future direction for high-performance PROFINET. | Next-generation motion control and precision manufacturing |
Teltonika switches cover CC-A and CC-B. CC-C and CC-D require specialised switching silicon with hardware timestamping and bandwidth reservation circuits that are not present in industrial Ethernet switches at this market tier. They are the domain of specialist automation switch vendors such as Siemens SCALANCE, Hirschmann, and Phoenix Contact FL SWITCH.
PROFINET Conformance Class A – What It Means for a Switch
CC-A in plain terms: the switch carries PROFINET traffic reliably and transparently, but it is not visible as a device to the PLC. The controller cannot interrogate it for topology or port status. It is infrastructure, not a participant.
A CC-A PROFINET network can use any industrial-grade Ethernet switch that meets the physical and performance requirements. Full duplex operation and QoS priority queuing are recommended so that PROFINET RT frames are prioritised over standard TCP/IP traffic. The switch itself does not need to understand PROFINET – it just forwards Ethernet frames reliably.
This is exactly what the Teltonika TSF and TSW entry and mid-range switch ranges provide. These switches deliver reliable, industrial-grade Ethernet switching with wide operating temperature ranges, DIN rail mounting, and PoE support where needed. They carry PROFINET Real-Time frames between PLCs and IO-Devices without issue. However, because they do not implement SNMP management, LLDP topology reporting, or the PROFINET device stack, they cannot fulfil the CC-B requirement for the network infrastructure to be a visible, manageable participant in the PROFINET system.
This is not a deficiency for the many PROFINET installations where CC-A is the correct and specified requirement. Building automation controllers, infrastructure monitoring panels, smaller machine cells, and applications where the PLC does not need to map the network topology are all well served by CC-A switches. The TSF and entry TSW models offer a cost-effective, rugged, and certified solution for these deployments.
PROFINET Conformance Class B – What More It Requires
CC-B in plain terms: the switch is itself a PROFINET IO device. The PLC can see it, interrogate its port status, map the entire network topology, and receive alarms when a cable is disconnected. MRP ring redundancy is supported, so a single cable break does not bring down the production line.
Three specific capabilities separate CC-B from CC-A in the context of an Ethernet switch.
SNMP and Network Diagnostics
CC-B requires the switch to support SNMP (Simple Network Management Protocol). This allows the PLC and any SNMP manager on the network to query the switch for port statistics, link status, bandwidth utilisation, and error counts. In TIA Portal, this information is available directly in the PLC engineering environment, allowing the automation engineer to diagnose network issues from the same tool used to program the PLC.
LLDP Topology Detection
LLDP (Link Layer Discovery Protocol) allows network devices to advertise themselves and their connected neighbours. PROFINET uses LLDP with extensions so that the IO-Controller can automatically discover and display the complete network topology – which device is connected to which switch port. If a device is plugged into the wrong port during commissioning or maintenance, the controller can identify this immediately. The topology map is also used for guided device replacement: when a CC-B device fails, the engineering tool can use the topology data to confirm the replacement is connected to the correct port before downloading configuration.
MRP – Media Redundancy Protocol
MRP (Media Redundancy Protocol, defined in IEC 62439-2) allows CC-B switches and devices to be connected in a ring topology. In normal operation, one port of the ring manager is blocked to prevent Ethernet loops. If a cable breaks anywhere in the ring, the ring manager detects the failure within milliseconds, unblocks its reserved port, and restores communication to all devices via the alternative path. MRP provides recovery times of under 200 ms in most configurations, which is fast enough for standard RT PROFINET applications. All devices in the MRP ring must support MRP – a single CC-A device without MRP support breaks the redundancy for the entire ring.
This is the fundamental reason why a CC-A switch cannot participate in the same MRP ring as CC-B devices. It lacks both the MRP protocol implementation and the managed switch firmware required to act as an MRP ring client or manager. The Teltonika SWM and TSW202/212 managed switches implement the full PROFINET device stack including SNMP, LLDP, and MRP, making them visible PROFINET participants that can be managed from TIA Portal and included in redundant ring topologies.
PROFINET Use Cases
Automotive Manufacturing
Body welding lines, paint shops, and final assembly stations use PROFINET to connect hundreds of robots, servo drives, safety PLCs, and I/O modules across a production hall. CC-B switches with MRP ring topology provide media redundancy so that a single cable fault does not halt production. Topology detection via LLDP allows the maintenance team to identify the exact location of a fault from the SCADA workstation without walking the line.
Food and Beverage Processing
Filling lines, conveyors, and packaging machines use PROFINET IO to connect sensors, actuators, and drives to a central PLC. CC-A infrastructure is typically sufficient for standalone machine cells. Lines integrating multiple machines from different manufacturers benefit from CC-B diagnostics, which allow the line PLC to receive port-level alarms if a device drops off the network during a production run.
Water and Wastewater Treatment
Treatment plant control systems use PROFINET to connect PLCs to motor control centres, valve actuators, level sensors, and flow meters. The extended operating temperature range of industrial switches such as the Teltonika TSW110 makes them suitable for pump house and outdoor cabinet environments. MRP ring redundancy is common on critical dosing and treatment loops where a network interruption could affect compliance with discharge consent conditions.
Machine Building and Panel Builders
Machine builders specifying PROFINET for their control panels need switches that fit standard 35 mm DIN rail with compact dimensions. The Teltonika TSW series is designed for exactly this application. For machines shipped to customers running SIMATIC PLC systems where the customer’s engineering team will manage the network via TIA Portal, TSW202 or TSW212 CC-B switches provide the topology visibility and diagnostics that the PLC engineer expects.
Building Automation and Infrastructure
HVAC controllers, access control systems, and fire suppression panels in large buildings use PROFINET for device communication. CC-A is the standard for this application, where the network is relatively small, device locations are fixed, and the PLC engineer does not need per-port switch diagnostics. TSW and TSF series switches provide the right level of capability at the right price point for building panel installations.
Teltonika PROFINET Conformance Class A Switches
All models below support PROFINET as reliable industrial Ethernet infrastructure (CC-A). They are suitable for any PROFINET network where the switch is used as transparent infrastructure rather than as a managed PROFINET IO device. All models are available from routerstore.com.
| Model | Ports and key spec |
|---|---|
| TSF SERIES – Fast Ethernet, Flat Form Factor | |
| TSF000 | 5x Fast Ethernet ports, 4x PoE+ out, flat design for space-constrained panels |
| TSF010 | 5x Ethernet ports, 3-pin power input, flat DIN rail design |
| TSW SERIES – Entry and Mid-Range Industrial Switches | |
| TSW010 | 5x Ethernet ports, integrated DIN rail bracket, plug and play, no configuration required |
| TSW030 | 8x Ethernet ports, DIN rail mounting, 2-pin power input |
| TSW040 | 8x PoE+ Ethernet ports, 240 W PoE budget, DIN rail bracket |
| TSW100 | 5x Gigabit Ethernet ports, PoE+ (802.3at), 120 W total PoE budget |
| TSW101 | 5x Gigabit Ethernet ports, 4x PoE+ ports, compact design suited to in-vehicle solutions |
| TSW110 | 5x Gigabit Ethernet ports, -40°C to +75°C operating range, industrial mounting options |
| TSW114 | 5x Gigabit Ethernet ports, integrated DIN rail bracket, plug and play |
| TSW200 | 8x Gigabit Ethernet with PoE+, 2x SFP uplink ports, 8x PoE+ ports |
| TSW210 | 8x Gigabit Ethernet, 2x SFP uplink ports, 7-57 V wide-range power input |
| TSW304 | 4x Gigabit Ethernet ports, integrated DIN rail bracket, 7-57 V power input |
Teltonika PROFINET Conformance Class B Switches
All models below support PROFINET CC-B. They implement the full PROFINET device stack and are visible as PROFINET IO devices in TIA Portal and compatible engineering tools. Each has a GSD file for import into the controller project. All support SNMP management, LLDP topology detection, and MRP ring redundancy. All models are available from routerstore.com.
For MRP ring deployments: every device in the ring must support MRP. A single CC-A switch in a ring with CC-B switches breaks the redundancy for all devices in that ring. Plan the network topology before specifying switch models if MRP is a requirement.
| Model | Ports and key spec |
|---|---|
| SWM SERIES – Managed Switches with PROFINET CC-B and MRP | |
| SWM280 | 24-port managed switch: 12x PoE+ Gigabit Ethernet ports + 12x Gigabit Ethernet ports. PROFINET CC-B and MRP support. High port count for large PROFINET cells. |
| SWM281 | 24x Gigabit Ethernet ports, no PoE, managed L2 switch. PROFINET CC-B and MRP support. |
| SWM282 | 24x PoE+ ports, managed PoE+ switch. PROFINET CC-B and MRP support. High PoE budget for device-dense installations. |
| TSW SERIES – Compact Managed Switches with PROFINET CC-B and MRP | |
| TSW202 | 8x Gigabit Ethernet ports with PoE+, managed. PROFINET CC-B and MRP support. Compact DIN rail form factor for panel-mounted PROFINET cells. |
| TSW212 | 8x Gigabit Ethernet ports, no PoE, managed L2 switch. PROFINET CC-B and MRP support. Wide-voltage industrial power input. |
Frequently Asked Questions
What is the difference between PROFINET and PROFIBUS?
PROFIBUS is a serial fieldbus protocol that uses a dedicated physical layer (RS-485 at speeds up to 12 Mbit/s) and a token-passing bus architecture. It was the dominant industrial automation protocol before Ethernet became practical for the factory floor. PROFINET is its successor, built on standard 100 Mbit/s (and now Gigabit) Ethernet, which allows for higher data rates, standard IT integration, and the additional diagnostic capabilities described in this page. PROFINET includes a PROFIBUS proxy function, allowing existing PROFIBUS devices to connect to a PROFINET network via a gateway without replacing the field devices.
Do I need a PROFINET-certified switch or will any industrial switch work?
For CC-A networks, any reliable industrial Ethernet switch that supports full duplex and ideally QoS priority queuing is suitable. Switches do not need PROFINET certification for CC-A infrastructure use. For CC-B networks, the switch must implement the PROFINET device stack, have a GSD file, and support SNMP, LLDP, and MRP. This requires a managed switch with specific firmware support – the Teltonika SWM and TSW202/212 are certified for this role. Using an unmanaged switch in a CC-B role is not possible regardless of how rugged or industrial-grade it is.
What is a GSD file and do I need one for the Teltonika CC-B switches?
A GSD (General Station Description) file is an XML file that describes a PROFINET device to the engineering tool (such as TIA Portal). It defines the device’s modules, submodules, supported data objects, and configuration options. When you add a PROFINET IO device to a project in TIA Portal, you import its GSD file so the tool knows how to configure it. The Teltonika TSW202, TSW212, and SWM series CC-B switches each have a GSD file available for import into TIA Portal. Contact routerstore.com or visit the Teltonika wiki to download the GSD file for the specific model.
Can PROFINET CC-A and CC-B switches coexist on the same network?
Yes, within limits. CC-A and CC-B devices can coexist on the same PROFINET network for standard IO communication. The key restriction is MRP rings: every device in an MRP ring must support MRP. If a CC-A switch is inserted into a ring containing CC-B devices, it cannot participate in MRP and will break the ring redundancy for the entire loop. Outside of ring topologies – in star or tree topologies – CC-A and CC-B switches can be mixed freely.
What is the operating temperature range of the Teltonika switches for PROFINET?
Operating temperature ranges vary by model. The TSW110 is rated to -40°C to +75°C, making it the most suitable model for outdoor cabinets and harsh environments. The SWM series and other TSW models are rated for industrial environments but may have a narrower range. Check the individual product datasheet or call routerstore.com on 0300 124 6181 for specific temperature ratings on any model.
Can I use Teltonika cellular routers alongside PROFINET switches?
Yes. Teltonika cellular routers are commonly used alongside PROFINET switches to provide the WAN connectivity for SCADA data, remote monitoring, and remote access to PLC programs. The router connects to the PROFINET switch’s uplink port, providing internet or private network access while the PROFINET IO communication operates entirely on the local network between the PLC and IO-Devices. Teltonika routers support VPN, firewall, and WAN failover features that are relevant for securing remote access to industrial networks. See our VPN on cellular routers guide for more detail.
Related Products and Further Reading
For PROFINET CC-A infrastructure in compact DIN rail panels, the TSW010, TSW110, and TSW114 are the most popular choices. For CC-B networks requiring topology diagnostics and MRP ring redundancy, the TSW202 and SWM series provide the managed switch capability needed. For cellular WAN connectivity alongside a PROFINET network, the Teltonika 4G router range and 5G router range integrate with any Ethernet-connected industrial network. For remote monitoring of the wider site, see the Teltonika RMS guide and our IoT SIM connectivity hub.