p-net-rtt

P-net

Profinet device stack for embedded systems

Web resources

• Source repository: https://github.com/rtlabs-com/p-net
• Documentation: https://rt-labs.com/docs/p-net
• Continuous integration: https://github.com/rtlabs-com/p-net/actions
• RT-Labs (stack integration, certification services and training): https://rt-labs.com

Key features

• Profinet v2.43

  • Conformance Class A and B
  • Real Time Class 1
  • Multiple Ethernet ports

• Easy to use

  • Extensive documentation and instructions on how to get started.
  • Build and run sample application on Raspberry Pi in 30 minutes.

• Portable

  • Written in C.
  • Linux, RTOS or bare metal.
  • Sources for supported port layers provided.

The RT-Labs Profinet stack p-net is used for Profinet device implementations. It is easy to use and provides a small footprint. It is especially well suited for embedded systems where resources are limited and efficiency is crucial. The stack is supplied with full sources including porting layers and a sample application.

Also C++ (any version) is supported for application development.

The main requirement on the platform is that it can send and receive raw Ethernet Layer 2 frames.

This software is dual-licensed, with GPL version 3 and a commercial license. If you intend to use this stack in a commercial product, you likely need to buy a license. See LICENSE.md for more details.

Getting started

See the tutorial in the documentation: https://rt-labs.com/docs/p-net/tutorial.html

Note that you need to include submodules when cloning:

git clone --recurse-submodules https://github.com/rtlabs-com/p-net.git

Features

• Multiple Ethernet ports (for Linux only, so far)
• TCP/IP
• LLDP
• SNMP
• RT (real-time)
• Address resolution
• Parameterization
• Process IO data exchange
• Alarm handling
• Configurable number of modules and sub-modules
• Bare-metal or OS
• Porting layer provided
• Supports I&M0 - I&M4. The I&M data is supported for the device, but not for individual modules.
• Shared device (connection to multiple controllers)

Limitations

• This is a device stack, which means that the IO-controller/master/PLC side is not supported.
• No media redundancy (No MRP support)
• Legacy startup mode is not fully implemented
• No support for RT_CLASS_UDP
• No support for DHCP
• No fast start-up
• No MC multicast device-to-device
• No support for shared inputs
• Supports only full connections, not the limited "DeviceAccess" connection type.
• No iPar (parameter server) support
• No support for time synchronization
• No UDP frames at alarm (just the default alarm mechanism is implemented)
• No ProfiDrive or ProfiSafe profiles.

Requirements

The platform must be able to send and receive raw Ethernet Layer 2 frames, and the Ethernet driver must be able to handle full size frames. It should also avoid copying data, for performance reasons.

• cmake 3.14 or later

For Linux:

• gcc 4.6 or later
• See the "Real-time properties of Linux" page in the documentation on how to improve Linux timing

For rt-kernel:

• Workbench 2020.1 or later

An example of microcontroller we have been using is the Infineon XMC4800, which has an ARM Cortex-M4 running at 144 MHz, with 2 MB Flash and 352 kB RAM. It runs rt-kernel, and we have tested it with 9 Profinet slots each having 8 digital inputs and 8 digital outputs (one bit each). The values are sent and received each millisecond (PLC watchdog setting 3 ms).

Dependencies

Some of the platform-dependent parts are located in the OSAL repository and the cmake-tools repository.

• https://github.com/rtlabs-com/osal
• https://github.com/rtlabs-com/cmake-tools

Those are downloaded automatically during install.

The p-net stack contains no third party components. Its external dependencies are:

• C-library
• An operating system (if used)
• For conformance class B you need an SNMP implementation. On Linux is net-snmp (BSD License) used http://www.net-snmp.org

Tools used for building, testing and documentation (not shipped in the resulting binaries):

• cmake (BSD 3-clause License) https://cmake.org
• gtest (BSD-3-Clause License) https://github.com/google/googletest
• Sphinx (BSD license) https://www.sphinx-doc.org
• Doxygen (GPL v2) https://www.doxygen.nl
• clang-format (Apache License 2.0) https://clang.llvm.org

Contributions

Contributions are welcome. If you want to contribute you will need to sign a Contributor License Agreement and send it to us either by e-mail or by physical mail. More information is available on https://rt-labs.com/contribution.