PROFINET Reference

Q: What is the difference between PROFINET RT and IRT?

PROFINET RT (Real-Time) uses standard Ethernet switches with VLAN priority tagging (priority 6, EtherType 0x8892) to achieve cycle times of 1-10ms with jitter under 1ms. It is suitable for general I/O control. PROFINET IRT (Isochronous Real-Time) uses specialized hardware with reserved time slots to achieve cycle times down to 31.25 microseconds with jitter under 1 microsecond, required for high-precision motion control and synchronized multi-axis drives.

Q: How does MRP media redundancy work in PROFINET?

MRP (Media Redundancy Protocol) provides network fault tolerance using a ring topology. One device acts as the MRP Manager, monitoring ring integrity by sending test frames. Other devices are MRP Clients. When a link failure occurs, the MRP Manager opens the ring to reroute traffic, achieving recovery times typically under 200ms (configurable down to faster recovery with MRP). This reference includes ring configuration parameters and failover behavior details.

Q: What is a GSD file and how is it used?

A GSD (General Station Description) file is an XML-based device description file (GSDML format for PROFINET) that defines an IO device's modules, submodules, parameters, and communication capabilities. Engineering tools like STEP 7 or TIA Portal import GSD files to configure devices in the project. The reference covers GSD file structure, module definitions, parameter access, and DAP (Device Access Point) configuration.

Q: How is PROFINET device addressing configured?

PROFINET devices are addressed using a combination of device name (station name) and IP address. The device name is written to the device using DCP (Discovery and Configuration Protocol) and must be unique on the network. IP addresses can be assigned via DCP or DHCP. IO data is addressed using slot and subslot numbers that correspond to physical or virtual module positions. This reference details the complete addressing scheme.

Q: What diagnostic capabilities does PROFINET provide?

PROFINET provides multi-level diagnostics: channel diagnostics for specific I/O point faults, module diagnostics for slot-level status, device diagnostics via I&M (Identification & Maintenance) data records 0-4, and network diagnostics through SNMP and LLDP. Alarms are classified by priority and transmitted via dedicated alarm frames to the controller. This reference covers diagnostic alarm types, I&M data structures, and monitoring approaches.

Q: What cycle times can PROFINET achieve?

PROFINET RT achieves cycle times from 1ms to 10ms (typical) using standard Ethernet infrastructure. PROFINET IRT achieves cycle times from 250 microseconds down to 31.25 microseconds using specialized ASIC-based switches with reserved bandwidth. The achievable cycle time depends on the number of IO devices, data volume per device, and network topology. This reference includes timing specifications for both RT and IRT classes.

Q: How does PROFIsafe work over PROFINET?

PROFIsafe is a safety communication profile that runs over standard PROFINET connections, adding a safety layer with CRC checks, sequence numbers, watchdog timers, and codename authentication. It supports safety functions up to SIL 3 (IEC 61508) / PL e (ISO 13849) without requiring dedicated safety cabling. The reference covers PROFIsafe telegram structure, F-parameter configuration, and safety-relevant diagnostic data.

Q: Can PROFINET coexist with other protocols on the same network?

Yes, PROFINET RT uses standard Ethernet frames and can coexist with TCP/IP, HTTP, and other protocols on the same physical network. PROFINET IRT requires reserved bandwidth for its isochronous phase but allows standard communication during the open phase. The reference covers network planning considerations, VLAN configuration, and bandwidth allocation for mixed-protocol environments.

Free reference guide: PROFINET Reference

23 results

About PROFINET Reference

The PROFINET Reference is a comprehensive, searchable guide to the PROFINET industrial Ethernet protocol used in factory automation. It covers the PROFINET IO communication model with Controller, IO Device, and IO Supervisor roles, real-time communication classes (RT and IRT), and the complete device configuration workflow using GSD (General Station Description) files. Each entry includes protocol details, configuration parameters, and practical examples from real automation projects.

This reference is organized into six categories: Architecture (PROFINET IO topology, controller-device relationships, slot/subslot addressing), Configuration (GSD file structure, IP assignment, device naming, STEP 7/TIA Portal setup), Redundancy (MRP media redundancy protocol, S2 system redundancy, ring topology configuration), Diagnostics (alarm channels, I&M data, SNMP-based monitoring, LLDP neighbor detection), Protocol (RT/IRT frame structure, VLAN priorities, EtherType 0x8892, cycle times), and Advanced Features (PROFIdrive motion control, PROFIsafe functional safety, time synchronization via PTCP).

Built for automation engineers, PLC programmers, and industrial network designers, this tool provides instant lookup for PROFINET-specific parameters such as RT cycle times (1-10ms typical), IRT jitter specifications (< 1 microsecond), MRP ring recovery times (< 200ms), and IO device addressing schemes. Whether you are configuring a Siemens S7-1500 controller with ET200SP remote I/O or troubleshooting PROFINET network issues, this reference delivers the technical details you need. All content runs entirely in your browser.

Key Features

PROFINET IO architecture reference with Controller, IO Device, and IO Supervisor role definitions and topology examples
RT and IRT real-time communication specifications including cycle times, jitter, VLAN priorities, and EtherType details
MRP (Media Redundancy Protocol) configuration for ring topology with recovery time parameters and failover behavior
GSD file structure reference for device integration, module definitions, and parameter configuration
Diagnostic and alarm handling reference covering channel diagnostics, I&M identification data, and SNMP monitoring
PROFIdrive and PROFIsafe integration details for motion control and functional safety applications
Network configuration parameters including IP addressing, device naming conventions, and LLDP neighbor discovery
Searchable across all six categories with instant filtering, code examples, and full dark mode support

Frequently Asked Questions

What is the difference between PROFINET RT and IRT?

PROFINET RT (Real-Time) uses standard Ethernet switches with VLAN priority tagging (priority 6, EtherType 0x8892) to achieve cycle times of 1-10ms with jitter under 1ms. It is suitable for general I/O control. PROFINET IRT (Isochronous Real-Time) uses specialized hardware with reserved time slots to achieve cycle times down to 31.25 microseconds with jitter under 1 microsecond, required for high-precision motion control and synchronized multi-axis drives.

How does MRP media redundancy work in PROFINET?

MRP (Media Redundancy Protocol) provides network fault tolerance using a ring topology. One device acts as the MRP Manager, monitoring ring integrity by sending test frames. Other devices are MRP Clients. When a link failure occurs, the MRP Manager opens the ring to reroute traffic, achieving recovery times typically under 200ms (configurable down to faster recovery with MRP). This reference includes ring configuration parameters and failover behavior details.

What is a GSD file and how is it used?

A GSD (General Station Description) file is an XML-based device description file (GSDML format for PROFINET) that defines an IO device's modules, submodules, parameters, and communication capabilities. Engineering tools like STEP 7 or TIA Portal import GSD files to configure devices in the project. The reference covers GSD file structure, module definitions, parameter access, and DAP (Device Access Point) configuration.

How is PROFINET device addressing configured?

PROFINET devices are addressed using a combination of device name (station name) and IP address. The device name is written to the device using DCP (Discovery and Configuration Protocol) and must be unique on the network. IP addresses can be assigned via DCP or DHCP. IO data is addressed using slot and subslot numbers that correspond to physical or virtual module positions. This reference details the complete addressing scheme.

What diagnostic capabilities does PROFINET provide?

PROFINET provides multi-level diagnostics: channel diagnostics for specific I/O point faults, module diagnostics for slot-level status, device diagnostics via I&M (Identification & Maintenance) data records 0-4, and network diagnostics through SNMP and LLDP. Alarms are classified by priority and transmitted via dedicated alarm frames to the controller. This reference covers diagnostic alarm types, I&M data structures, and monitoring approaches.

What cycle times can PROFINET achieve?

PROFINET RT achieves cycle times from 1ms to 10ms (typical) using standard Ethernet infrastructure. PROFINET IRT achieves cycle times from 250 microseconds down to 31.25 microseconds using specialized ASIC-based switches with reserved bandwidth. The achievable cycle time depends on the number of IO devices, data volume per device, and network topology. This reference includes timing specifications for both RT and IRT classes.

How does PROFIsafe work over PROFINET?

PROFIsafe is a safety communication profile that runs over standard PROFINET connections, adding a safety layer with CRC checks, sequence numbers, watchdog timers, and codename authentication. It supports safety functions up to SIL 3 (IEC 61508) / PL e (ISO 13849) without requiring dedicated safety cabling. The reference covers PROFIsafe telegram structure, F-parameter configuration, and safety-relevant diagnostic data.

Can PROFINET coexist with other protocols on the same network?

Yes, PROFINET RT uses standard Ethernet frames and can coexist with TCP/IP, HTTP, and other protocols on the same physical network. PROFINET IRT requires reserved bandwidth for its isochronous phase but allows standard communication during the open phase. The reference covers network planning considerations, VLAN configuration, and bandwidth allocation for mixed-protocol environments.