PLC Protocol Converter Using Shared Memory for SCADA Integration
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Solution Overview
Problem
Industrial PLC devices often require extensive configuration and shutdowns when adding communication cards to support different communication protocols, which can be disruptive and limit data access.
Innovation Solution
A PLC protocol converter system that uses a shared memory array to store data from PLC devices, allowing communication using one protocol while serving data in another, enabling seamless communication between PLC devices and SCADA systems without requiring configuration within the PLC or processor restarts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a communication card is added to the PLC to support different communication protocols, then the PLC can communicate with more devices, but it requires extensive PLC configuration and often a plant shutdown
Solution Approach 1:
The patent introduces a protocol converter as an intermediary device that sits between the PLC and the network. This converter handles protocol translation, allowing the PLC to communicate with devices using different protocols without requiring configuration changes to the PLC itself. The converter mediates all communication, translating between the PLC's native protocol and various network protocols.
Solution Approach 2:
The system is segmented into distinct functional components: the PLC, the protocol converter, and the network devices. By separating the protocol translation function into a dedicated converter device, the complexity is isolated from the PLC, allowing the PLC to remain unchanged while still achieving multi-protocol compatibility.
2Adaptability or versatility
If a communication card is added to the PLC, then the PLC can speak different communication protocols, but it frequently requires a plant shutdown
Solution Approach 1:
The protocol converter acts as an external intermediary that does not require integration into the PLC's internal architecture. This allows the converter to be added or configured without shutting down the PLC or the industrial process it controls, maintaining continuous operation while enabling protocol flexibility.
Solution Approach 2:
Instead of adding protocol capability within the PLC's internal dimension (which would require shutdowns), the solution moves the protocol translation function to an external dimension via the protocol converter. This dimensional shift allows protocol support to be added without interfering with the PLC's operational continuity.
3Adaptability or versatility
If a communication card is added to the PLC, then the PLC can access more data, but some communication cards only provide access to limited data from a PLC device
Solution Approach 1:
The protocol converter serves as a comprehensive intermediary that can access and translate all types of PLC data including memory, registers, and database locations. It maintains a mapping between PLC address spaces and network protocol address spaces, ensuring that no data is lost in translation and that full data accessibility is preserved across different protocols.
Data Source
AI summary
A programmable logic controller (PLC) protocol converter is disclosed that allows a supervisory control and data acquisition (SCADA) system to effectively communicate with a PLC device using a desired communications protocol, particularly in cases where the PLC device does not “speak” the desired communications protocol. A first thread may be configured to continually read PLC addresses, one at a time, using a communications protocol understood by the PLC device. The first thread may store the data values in the shared data array within program memory. Thus, the first thread exposes data from the PLC device, as specified in the configuration file. At the same time, a second thread may be configured to serve the data in the shared data array according to a second communications protocol, e.g., to the SCADA system.