Application #1: Single-Host Roundtrip TSN Transport¶
The following section is applicable to:
The single-host roundtrip TSN transport example uses multiple instances of the EC Protocol Bridge and the OPC UA plug-in to create a roundtrip OPC UA communication loop. The example also demonstrates how to configure the OPC UA plug-in to take advantage of Time Sensitive Networking. The configuration for each segment is described in the diagram below.
In this example, the OPC UA Server will update a variable periodically. An OPC UA plug-in instantiated as an OPC UA Client (EC Protocol Bridge A) will connect to the OPC UA Server and share the variable with an OPC UA plug-in instantiated as an OPC UA Publisher (EC Protocol Bridge A). At this point, the variable has now been converted from OPC UA Client/Server model, to OPC UA Pub/Sub model. An OPC UA plug-in instantiated as an OPC UA Subscriber (EC Protocol Bridge B) will receive the published variable data and re-publish it. From here, the variable follows the same path but in reverse, finally returning to the OPC UA Server, and thus completing the roundtrip loop.
The single host roundtrip example is available in three different configurations, each utilizing a different transport method, with some being able to take advantage of Time Sensitive Networking.
Attention
The OPC UA plug-in assigns CPU affinity and requires elevated permissions to run correctly. Verify that the user executing the EC Protocol Bridge has elevated permissions.
UDP Transport¶
The OPC UA Publisher/Subscriber nodes are configured to use the UDP transport layer to send packets. With this configuration, OPC UA traffic will be treated equivalent to normal bulk traffic.
- Prerequisites
Make sure that the EC Protocol Bridge is installed. For more information, refer to Install Edge Control Protocol Bridge.
- Running the Example
To start the example using UDP transport:
$ /opt/ec-protocol-bridge/plg-opcua-rt/examples/singlehost/udp_transport.sh
Tip
It may be necessary to create a default route before localhost multicast functions correctly. A simple method to establish a default route is to connect the system to a network with a DHCP server and receive an IP address.
- Expected Results
After completion, the script should output “Test successful!” along with additional information:
TSN Transport without Priority¶
The OPC UA Publisher/Subscriber nodes are configured to use Ethernet II frames with VLAN ID (IEEE 802.1Q) specified to send packets. With this configuration, OPC UA traffic will be routed through a VLAN, but not subject to Priority rules (such as MQPRIO or TAPRIO). Unless the VLAN is subject to filtering, the OPC UA traffic will be treated equivalent to normal bulk traffic.
- Prerequisites
Make sure that the EC Protocol Bridge is installed. For more information, refer to Install Edge Control Protocol Bridge.
- Running the Example
To start the example using TSN transport without priority:
$ /opt/ec-protocol-bridge/plg-opcua-rt/examples/singlehost/tsn_transport_without_priority.sh
Tip
It may be necessary to create a default route before localhost multicast functions correctly. A simple method to establish a default route is to connect the system to a network with a DHCP server and receive an IP address.
- Expected Results
After completion, the script should output “Test successful!” along with additional information:
TSN Transport with Priority¶
The OPC UA Publisher/Subscriber nodes are configured to use Ethernet II frames with VLAN ID and Priority (IEEE 802.1Q) specified to send packets. With this configuration, OPC UA traffic will be subject to Queuing Discipline rules such as Linux Traffic Control (TC). Using TSN transport with priority enables the OPC UA traffic to adhere to strict timing requirements, typically required of real-time applications. With this model, it is possible to achieve deterministic communication between OPC UA Client/Server and Publish/Subscribe applications.
Attention
Queuing Discipline rules such as MQPRIO and TAPRIO are not enabled by default in ECI. These rules are typically enabled when configuring a Time Sensitive Network (TSN). Please follow section Overview of IEEE 802.1Q-2018 Enhancements for Scheduled Traffic (EST) for further instructions about configuring Queuing Discipline rules.
- Prerequisites
Make sure that the EC Protocol Bridge is installed. For more information, refer to Install Edge Control Protocol Bridge.
- Running the Example
To start the example using TSN transport with priority:
$ /opt/ec-protocol-bridge/plg-opcua-rt/examples/singlehost/tsn_transport_with_priority.sh
Tip
It may be necessary to create a default route before localhost multicast functions correctly. A simple method to establish a default route is to connect the system to a network with a DHCP server and receive an IP address.
- Expected Results
After completion, the script should output “Test successful!” along with additional information:
