The tests were carried out at the '5G-Industry Campus Europe' in Aachen. The 5G-Industry Campus Europe is Europe's largest 5G research network and spans a total of four factory halls and 1 km2 of open space where industrial use cases are being investigated. The factory halls of the WZL, the Fraunhofer IPT and the FIR at RWTH Aachen University are comparable to industrial production environments with their mechanical equipment and processes. The test setup used for the 5G test essentially consists of three components:

• the 5G communication infrastructure,
• an S7 PLC and an IO device (both Siemens) running a Profisafe application with functional safety
• and a 5G device, IPCs and two Dataeagle devices from Schildknecht, which tunnel the Profinet protocol from the PLC to the IO device via the 5G network.

The radio data systems

Schildknecht 's Dataeagle devices are data radio systems that wirelessly connect the PLC and the IO module, enabling wireless Profinet communication between these two devices while converting the layer 2 Profinet frames into layer 3 IP packets. In addition to monitoring, the wireless data systems pre-process the Profinet fieldbus telegrams to maintain fieldbus communication regardless of which connection is used between the two nodes in order to meet the requirements of the control technology (e.g. transmission time requirements, number of retransmissions). In addition, they keep the state of the Profinet protocol stable using pre-processing algorithms to meet hard cable-based timing requirements of the controller. Without such a procedure, fieldbus errors can occur, leading to machine downtimes of minutes if a data packet reaches its destination outside the Profinet/Profisafe time window.

The 5G infrastructure

Ericsson's 5G Industry Campus Network Europe in Aachen was used as the communication infrastructure for the 5G testbed. The infrastructures at each location of this network contain all the nodes required to build a fully capable, state-of-the-art 5G network. This 5G campus network is based on the B40 band (2.3 GHz) as an anchor band and uses the NR band N78 (3.7 GHz) with a bandwidth of 100 MHz for data transmission. The current 5G infrastructure is based on Release 15 of the 3GPP 5G specification. The infrastructure is also equipped with a 5G RAN and core network, which is currently not optimized for latency-optimized communication (URLLC).

Figure 2: The testbed of the second scenario with a 5G device (UE) and a central PLC (UE), which is also connected via 5G (UE to UE).

© Schildknecht

On the mobile side of the test setup, a Qualcomm X55 chipset-based 5G device is used to establish the wireless network connection. The IPCs have the functionality to perform layer 2 tunneling, as this is not possible directly on the UE (user equipment). In addition, 5G technology only supports IP connectivity (layer 3). The user equipment establishes the 5G connectivity to the base station. In the testbed, this function is performed by a 5G device.

The two testbeds 'UE to Local Breakout' and 'UE to UE' are intended to simulate two real cases in a production environment and are shown in Figures 1 and 2: The measurement data can be read directly from the Dataeagle radio data system (on the left in the picture) via its maintenance and configuration interface; here, the diagnostic function is used to determine the latency of the communication link.

The requirements for the test cases

For the best possible safety communication in conjunction with Profinet, a 5G system must meet the following requirements: The Profinet update time of the PLC must be set to 1 ms, which means that a Profinet packet is generated and transmitted to the IO module every millisecond.

The standard TDD pattern (Time Division Duplex) with dynamic scheduling must be used in the 5G system; optimization in the 5G radio access network, such as pre-sheduling, is deliberately omitted.