empowering communication

PROFINET IRT: When Real-Time is not enough

Why do I need PROFINET IRT?

Industrial communication protocols such as PROFINET, EtherCAT and Ethernet/IP are classified as real-time communication protocols. These protocols can already achieve cycle times as low as 1 millisecond and jitter between 10 and 100 microseconds.

In some cases, however, even this level of performance isn’t enough. The fact of the matter is: it takes time to transmit and process data. In certain applications, it is critical that this time be precisely synchronized to ensure that production steps are performed correctly.

This is particularly true in motion control, where the demands for speed and performance in data communication have increased to the point where the cycle times of standard real-time PROFINET are no longer fast enough, and other key metrics such as jitter and determinism no longer meet the required standards.

For example, a robotic arm must be in a precisely defined position at a specific time to pick up or process a part. If the arm is even slightly early or late, the process can be severely disrupted. In such cases, the transmission and processing of data must be both fast and reliable.

PROFINET IRT is used wherever standard real-time communication reaches its limits and extremely accurate synchronization at exceptionally high speeds in data communication are required.

The inside of a factory with a conveyor belt and grey boxes. On the right side is the PROFINET logo.
How Does PROFINET IRT Work?

PROFINET IRT requires strict determinism in the transmission of specific data packets within the network. This means that data must be received, processed, and forwarded in a precise sequence within a predetermined time frame, without being affected by delays such as network collisions or jitter.

To do this, a PROFINET IRT network allocates specific time slots for handling time-critical data. For instance, if 20% of the network traffic is reserved for IRT communication, i.e., PROFINET IRT, the network traffic is divided into five time segments:

  • One segment is dedicated to IRT communication
  • The remaining four segments are reserved for regular real-time communication

In this case, the network operates as a standard PROFINET network 80% of the time. During the remaining 20%, only PROFINET IRT-relevant data packets are processed, ensuring synchronized and deterministic transmission. While IRT communication is taking place, regular PROFINET data packets are buffered and processed when the IRT time segment is complete.

A picture with numerous columns lined up in it. Every fifth column is labeled IRT, while the rest is labeled RT.
For this system to work effectively, a PROFINET IRT network must meet two essential requirements:
Synchronization across all IRT devices

A consistent synchronization cycle must be maintained across all PROFINET IRT devices. This is managed by a high-precision clock that is shared by all devices. This and additional mechanisms such as the Precision Time Protocol (PTP) are defined in the IEEE 1588 standard. PROFINET IRT extends this standard with the Precision Transparent Clock Protocol (PTCP). PTCP not only maintains a shared clock between PROFINET IRT devices, but also calculates delays between network switches and the associated wiring.

An icon of acomputer display with a loading icon in the middle.
Buffering capabilities

Additional circuitry within the network switch is required to buffer any non-IRT Ethernet traffic received during the designated IRT communication time.

PROFINET IRT with Hilscher & netX

In order to meet the requirements of such time-critical data communication, it is necessary to intervene on layer 1 and layer 2 of the OSI model, in particular on the MAC layer. This is necessary so that the network devices can provide the IRT time segments during which the Ethernet communication is converted to a TDMA (Time Division Multiple Access) medium. The rest of the time, during regular PROFINET communication, the data transmission works as a standard CSMA-CD (Carrier Sense Multiple Access - Collision Detect) medium.

Hilscher is one of the few suppliers worldwide to offer PROFINET IRT for controller applications. This is made possible by Hilscher’s netX communication controllers, which are developed together with the corresponding protocol software.

Transport LayerSession LayerPresentation LayerApplication LayerNetwork LayerDataLink LayerPhysical LayerModified Ethernethardware-based RTEHTTP, SNMP, SMTP, FTP, LDAP and similarIE Protocols likePROFINET, EtherCAT, ...Specific Real-Timehardware and functions(for example PROFINETIRT, Sercos, EtherCAT,Powerlink or TSN)Ethernet PHYTransport LayerSession LayerPresentation LayerApplication LayerNetwork LayerDataLink LayerPhysical LayerLegacy FieldbusStandard Ethernethardware-based RTEIP-Multicast IPEthernet MACEthernet PHYHTTP, SNMP, SMTP, FTP, LDAP and similarIE Protocols likePROFINET RT, EtherNet/IP(CIP), Modbus, ...UDPTCP

netX enables PROFINET IRT

Hilscher addresses this challenge with its netX technology. The netX controllers feature a unique xC structure on OSI layers 1 and 2. Using these programmable microcontrollers and Hilscher’s PROFINET protocol stack, the behavior of a PROFINET network can be defined on the first two OSI layers.

A graphical representation of the netX Basic technology switch architecture 100Mbit.

Flexible microcode from Hilscher

A key feature of netX is that this behavior isn’t hardcoded, but can be flexibly adjusted via microcode. With the microcode provided by Hilscher, users have access to the interface between layer 2 and layer 3.

A graphical representation of the netX Basic technology switch architecture 100Mbit.

If you already have a PROFINET solution in place, the first step is to check whether your hardware is IRT-capable. In most cases, it is not, as both hardware and software must meet specific requirements to transmit data according to the IRT standard. These requirements go beyond what is needed for most industrial applications and are typically only needed in high-performance systems, such as those used in motion control or robotics. Unfortunately, many PROFINET-enabled devices are not compatible with PROFINET IRT. In the worst case, a PROFINET IRT network will have to be treated and developed completely separate from your existing installations.

PROFINET and PROFINET IRT with netX

netX technology makes the transition much easier. The necessary PROFINET IRT configurations are already integrated in our standard PROFINET stack, and every netX communication controller comes with the required xC structure. You don’t need to make any changes to either your hardware or software. All you need to do is configure your network.

The same also applies to other network technologies such as EtherCAT. Thanks to the multiprotocol capability of netX, the same hardware can also support EtherCAT.

 

A black square with netX written on it on colorful background. On the right side is a PROFINET logo.

Different cable lengths introduce additional jitter, a physical property that is unavoidable and requires special attention when implementing a PROFINET IRT network.

For example, a data packet sent over a 10-cm cable will have a shorter transmission time than one sent over a 100-meter cable. These different cable lengths and the resulting jitter during data packet transmission must be taken into account in a PROFINET IRT network to ensure that the controller can properly manage the devices on the network.

Hilscher provides a handy tool called the Topology Editor that allows users to map their plant layout and account for the cable lengths connecting their devices.

What devices are suitable for PROFINET IRT?

Devices that meet the requirements for PROFINET IRT are classified as Conformance Class C (CC-C) as part of the PROFINET certification process. This class covers clocked communication with cycle times as low as 32.5 microseconds. CC-C is the most advanced and demanding conformance class for PROFINET. There are other conformance classes as well: CC-A, the basic class, supports “normal” real-time communication, acyclic real-time transmission, and standard TCP-IP Ethernet. CC-B builds on CC-A by adding support for the Simple Network Management (SNMP) protocol. The classes are cumulative, i.e., CC-C not only supports IRT communication, but also includes all features of CC-A and CC-B.

Hilscher’s netX technology is fully compliant with Conformance Class C, as our PROFINET stack already includes all necessary software functions. On the hardware side, our netX communication controllers are also equipped for IRT applications as standard.

PROFINET conformity classABC
Real-time data exchange with cycle times of up to 1 ms
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Alarm and diagnostic functions
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Support for network topology
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SNMP support 
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Real-time data exchange with cycle times down to 31.25µs  
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Our PROFINET PC cards

PCI Express- 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

用于扩展温度范围 PCI Express - 实时以太网的 PC ‍板卡

用于基于 PC 的自动化通讯板卡

‍半尺寸 MiniPCI Express- 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

‍实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

‍实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

M.2 2230 Key A+E 实时以太网 PC 板卡

用于基于 PC 的自动化通讯板卡

M.2 3042 Key B+M 实时以太网 PC 板卡

用于基于 PC 的自动化通讯板卡

‍实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

带 M12 连接器的实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

M.2 2242 Key B+M 实时以太网 PC 板卡

用于基于 PC 的自动化通讯板卡

‍Low Profile CI Express- 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

‍‍带有 NVRAM Low Profile CI Express- 实时以太网的 PC ‍板卡

用于基于 PC 的自动化通讯板卡

‍‍带有 NVRAM Mini PCI Express - 实时以太网的 PC ‍板卡

用于基于 PC 的自动化通讯板卡

MiniPCI Express- 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

‍实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

带 M12 连接器的实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

配有 NVRAM 和扩展温度 Mini PCI Express 实时以太网的 PC 板卡

用于基于 PC 的自动化通讯板卡

不带散热器 Mini PCI Express - 实时以太网的 PC ‍板卡

用于基于 PC 的自动化通讯板卡

用于扩展温度范围 MiniPCI Express - 实时以太网的 PC ‍板卡

用于基于 PC 的自动化通讯板卡

PCI - 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

CompactPCI- 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

MiniPCI - 实时以太网 PC ‍板卡

用于基于 PC 的自动化通讯板卡

‍实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

带 M12 连接器的实时以太网独立网络接口

用于基于 PC 的自动化通讯板卡

Our embedded modules for PROFINET

通讯模块双端口内存 实时以太网

用于自动化的灵活通讯模块

SPI - 实时以太网从站通讯模块

用于自动化的灵活通讯模块

通讯模块双端口内存 实时以太网

用于自动化的灵活通讯模块

SPI - 实时以太网从站通讯模块

用于自动化的灵活通讯模块

comX 评估板

适用于所有 comX 类型的开发平台

‌netX 90 芯片载体 - 预加载协议栈

经过全面测试和加载的超紧凑 netX 90 设计

NetX 90 芯片载体,具有额外的存储器 预加载协议栈

经过全面测试和预加载的超紧凑 netX 90 设计

netRAPID H90 评估板 - 实时以太网和现场总线

配备 NRP H90-RE\F8D8

具有附加存储器的netx51芯片载体 - 实时以太网从站

即可焊锡的 netX 设计,邮票大小

netRAPID 51 评估板 - 实时以太网

配备 NRP 51-RE

具有变压器的‌netX 52芯片载体 - 实时以太网从站

即可焊锡的 netX 设计,邮票大小

netRAPID 52 评估板 - 实时以太网

 

PCI Express- 实时以太网可交换模块

可随时安装在输送链中

SPI - 实时以太网从站可交换模块

可随时安装在输送链中

可交换模块双端口内存 实时以太网

可随时安装在输送链中

netJACK 评估板双端口内存

适用于具有双端口内存或SPI的每个netJACK

netJACK 评估板 PCI Express

适用于任何带有 PCI Express 的 netJACK

用于光纤电缆的DIL-32通讯IC - PROFINET IO 设备

用于带有光纤电缆连接的简单从站设备的通讯

‌不带散热器的 DIL-32 通讯 IC - 实时以太网从站

用于无自带主处理器的简单从站设备的通讯

‌DIL-32 通讯 IC - 实时以太网从站

用于无自带主处理器的简单从站设备的通讯

带光纤电缆的 netIC 评估板 - PROFINET IO 设备

带光纤电缆的评估平台netIC

用于光纤电缆的DIL-32通讯IC - PROFINET IO 设备

用于带有光纤电缆连接的简单从站设备的通讯

netIC 评估板 - 实时以太网从站

单个评估平台,适用于所有实时以太网协议

‌DIL-32 通讯 IC - 实时以太网从站

用于无自带主处理器的简单从站设备的通讯

Our gateways for PROFINET

媒体交换机 SPE 至 RTE

使用实时以太网协议连接单对以太网网络

CANopen 到以太网的网关

经济的入门级网关,用于简单转换

CC-Link IE Field从站到 PROFINET IO 设备的网关

CC-Link IE Field与PROFINET之间的数据耦合

实时以太网到 DeviceNet 的网关

用于高要求转换的高端网关

PROFIBUS DP 到以太网的网关

经济的入门级网关,用于简单转换

网关实时以太网到实时以太网

两个实时以太网网络之间的数据传输

网关实时以太网到Modbus RTU、3964R或串行(ASCII /可编程)

用于高要求转换的高端网关

DeviceNet 到 以太网的网关

经济的入门级网关,用于简单转换

连接头形式的 PROFINET / PROFIBUS 代理服务器

升级 PROFIBUS 从站到 PROFINET

网关串行(ASCII)或Modbus RTU至以太网

经济的入门级网关,用于简单转换

实时以太网到 CC-Link 从站的网关

用于高要求转换的高端网关

CC-Link 从站到以太网的网关

经济的入门级网关,用于简单转换

实时以太网到以太网的网关

用于高要求转换的高端网关

实时以太网到 PROFIBUS DP 的网关

用于高要求转换的高端网关

实时以太网到 CANopen 的网关

用于高要求转换的高端网关

以太网 LAN PROFINET IO 控制器

用于 DIN 导轨的 LAN 控制 PROFINET IO 控制器

以太网LAN实时以太网多协议

用于DIN导轨的局域网控制实时以太网主站

PROFINET IO 设备到 SmartWire-DT 的网关

SmartWire-DT 连接到实时以太网 PROFINET 系统

Related links
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