Field Device Data Exchange Using Brokered Request-Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The publish-subscribe communication principle, commonly used in industrial applications and IoT environments, does not allow field devices to actively request information from each other, limiting their ability to exchange data based on request-response interactions.
Innovation Solution
Implementing a request-response mechanism within the publish-subscribe principle by making a unique field device identifier known to the requesting device, allowing it to send requests directly to the responding device, and using specific message titles and identifiers to differentiate request and response messages, enabling direct communication and data exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the publish-subscribe principle is used for communication between field devices, then field devices can exchange data without knowing each other's structure and participants, but field devices cannot actively request information from each other
Solution Approach 1:
The message title is segmented into multiple components including topic, field device identifier, and message type. This segmentation allows the system to maintain the publish-subscribe structure while enabling targeted information requests by specificing the responding field device's identifier in the message title, thus resolving the contradiction between ease of communication establishment and the ability to actively request information
Solution Approach 2:
The data broker acts as an intermediary that receives request messages from requesting field devices and forwards them to the appropriate responding field devices based on the field device identifier in the message title. This intermediary enables active information requests while maintaining the indirect communication structure of publish-subscribe, allowing field devices to request information without directly addressing each other
2Device complexity
If field devices use publish-subscribe communication, then they don't need to know the communication network structure and participants, but they lack direct communication capabilities
Solution Approach 1:
The system adds a new dimension to the message title structure by incorporating the responding field device's identifier as a specific component. This dimensional addition to the message title allows requests to be routed to specific devices while maintaining the overall publish-subscribe framework, enabling direct communication capability without increasing the complexity of network structure knowledge for individual field devices
3Productivity
If request-response communication is implemented over publish-subscribe, then field devices can actively exchange data, but message routing complexity increases
Solution Approach 1:
The system performs preliminary action by including the responding field device's identifier in the request message title before the message is routed. This pre-specification of the target device in the message title allows the data broker to efficiently route messages without complex real-time routing logic, maintaining low routing complexity while enabling active data exchange and improving productivity
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method (1) and a corresponding communication system (4) for exchanging data between several field devices (2, 2a, 2b) are described and illustrated, wherein the field devices (2, 2a, 2b) are in a communication link based on the publish-subscribe principle via a data broker (3) with broker functionality, wherein at least one field device (2, 2a, 2b) sends at least one message with a message title to the data broker (3) (publish), wherein at least one field device (2, 2a, 2b) subscribes to a message with at least one specific component of a message title from the data broker (3) (subscribe), wherein the message sent to the data broker (3) is received by the data broker (3) and the data broker (3) forwards the received message to the at least one field device (2).which field device (2) has subscribed to the message with the corresponding part of the message title at the data broker (3). On-demand communication between field devices (2, 2a, 2b) is implemented by means of a request-response-based exchange of data between a requesting field device (2a) and a responding field device (2b) using the publish-subscribe principle, by making a unique field device identifier (F_Resp_ID) of the responding field device (2b) known to at least the requesting field device (2a) (5), by having the responding field device (2b) subscribe to request messages (6) (subscribe: f(F_Resp_ID)), the message titles of which include an indication (f(F_Resp_ID)) of the field device identifier (F_Resp_ID) of the responding field device (2b), and by having the requesting field device (2a) subscribe to response messages (7) (subscribe: Req_ID).whose message title includes a request identifier (Req_ID) known to the requesting field device (2a), that the requesting field device (2a) sends a request message (6) to the data broker (3), wherein the message title of the request message (6) includes the request identifier (Req_ID) and the specification (f(F_Resp_ID)) for the field device identifier (F Resp ID) of the responding field device (2b), that the responding field device (2b) receives the request message (6) of the requesting field device (2a) due to the subscription of the request messages (6), evaluates the request message (6) (8) and sends a corresponding reply message (7) to the data broker (3), wherein the message title of the reply message (7) includes at least the request identifier (Req_ID) and that the requesting field device (2a) due to the subscription of the The reply message (7) is received from the responding field device (2b).