1. Why OPC UA is needed?
Industrial automation is the heart and soul of I4.0. Implementing a proper communication protocol is the key to a successful automation system, which usually involves lots of control systems and smart field devices. These controllers need proper semantic communication protocol, for optimum results, and OPC UA is one option that provides this. It also provides plug and play connectivity for proprietary industrial devices. It acts as an interface between discrete data sources and is perfect for remote applications.
2. Is OPC UA open source?
Yes. OPC UA is open source. The OPC Foundation announced its open-source repository on the open-source GitHub web site at http://github.com/opcfoundation. This helps to overcome the hurdles that may arise during the implementation of OPC UA architecture. The open source enables easy access, which can be optimally utilized by research organizations and end-users interested to assess the technology.
3. What is the “Reverse Hello” scenario that helps to understand the various conditions under which OPC UA Server initiates connection with the OPC UA Client?
Nowadays, most of the standards suggest to avoid inbound request (top down traffic) to be on safer side. Let’s assume, In your plant there is a strict policy implemented to avoid inbound request from top down. This has been adopted in most of the places nowadays in order to not expose the ports and to avoid from malicious traffic. In this scenario the reverse hello will help. You no need open the client to sever inbound port. Instead, the server will initiate reverse hello connection bottom up connection and from there data exchange happens.
4. How to integrate an OPC UA server and a OPC DA (Classic) server in an embedded industrial setup?
To answer your question, yes, we definitely recommend OPC UA over OPC DA. But first, we need to understand the product requirements in terms of backward compatibility, customer install base and their willingness to upgrade etc.
Our uOPC Suite is a plug and play purpose-built platform that is designed to provide complete control over the IoT universe. uOPC Suite leverages OPC UA that serves as a fundamental gateway technology to cloud-enable industrial instruments, enabling data and device management, and critical insights for efficient and seamless performance.
5. Does the broker exist in the Pub-Sub over TSN network? If yes, then does the broker essentially have to be a TSN node?
To answer the first question, yes, broker exists in the Pub/Sub + Time-Sensitive Networking (TSN) architecture. However, the broker cannot be an TSN node.
Basically, TSN is a switch. Whereas a broker is used to store the data and expose it to all the subscribers. The broker can be anyone of the messaging protocols like MQTT or AMQP.
6. Does the network hold the data if the communication between the OPC UA client and server breaks?
The OPC UA server will retain the last known data in case of a client/server communication failure.
6. If the client changes few parameters out of the total subscribed parameters, does the server reflects just the changed parameters or all the parameters?
It all depends on the OPC UA version that is available for the application.
- In case of OPC UA Client/Server model, it will send only the changed parameters
- In case of OPC UA Pub/Sub, it depends on system configuration where it can publish all the last read parameter values or only the changed parameters values
8. What is Time Sensitive Network (TSN)?
In the current network landscape, the standard Ethernet communication is not deterministic. It doesn’t guarantee timely delivery of the packets.
Deterministic communication is important to multiple industries (for example, aerospace, automotive, manufacturing, transportation, and utilities). Providing a means for determinism over standard Ethernet enables new levels of connectivity and optimization, leading to cost savings for many industries.
Time Sensitive Networking (TSN) is an Ethernet standard for networks to transfer time sensitive data. TSN guarantees the delivery of packets within a time boundary. It is a Layer 2 technology that focuses on creating a convergence between information technology (IT) and industrial operational technology (OT) by extending and adapting existing Ethernet standards.
9. How to develop an interface for TSN?
“This question requires an in depth knowledge of the TSN architecture. However, to gain a better technical understanding and perspective on how TSN works and how it can be used, please go through this paper as an initial reading. https://www.cisco.com/c/dam/en/us/solutions/collateral/industry-solutions/white-paper-c11-738950.pdf
10. How many different types of OPC Clients can be connected to an OPC Server?
There are multiple answers to your question. However, they all depend the OPC server configuration at the time of initial setup. Below are some of the possible scenarios that determine the number of OPC clients that can connect to an OPC server:
- It is possible for the server to define a maximum limit on number of simultaneous connection.
- Purely based on the availability of resources (Memory, CPU etc.,)
For example, the server may keep accepting up to 10 client connections without any subscriptions and may reject 11th connection as it runs out of memory.
It may accept two clients with subscription of 100 tags for each client, may run out of memory and reject the third connection.
- It is possible for the server to dynamically determine if it should accept any new connection based on its current state and internal application logic.
11. How is security aspect taken care in the OPC Pub-Sub?
To answer your question, please refer to the Part 1 of this webinar series where OPC UA security is covered. The security handling of PubSub involves the following aspects.
- Security group management
- Key management
- Handshaking with keys etc.
12. Does the same SDK work both for TSN and Non-TSN network?
The TSN part is just the application profile. So, from the developer perspective, the SDK will most probably be the same. However, it depends on the vendor and design of the SDK.