Virtual-Device PLC Testing for Closed-Loop Fault Verification
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Solution Overview
Problem
Existing PLC testing methods lack loop-locked motion control over external devices, resulting in low test reliability due to simplified motion mechanisms of external devices, which compromises the effectiveness of fault processing logic verification.
Innovation Solution
A PLC testing system and method utilizing a virtual device to simulate field real devices, enabling fault signal injection and execution of corresponding fault processing logic, with manual intervention simulation for closed-loop verification and continuous testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a virtual device is used to simulate field real devices, then test reliability is improved through loop-locked verification, but device complexity increases
Solution Approach 1:
The patent creates a virtual device that copies the essential characteristics and behavior of field real devices. This virtual copy includes simulated motion mechanisms and control loops that replicate the actual device's response to PLC commands, enabling reliable testing without using the complex physical device
Solution Approach 2:
The virtual device acts as an intermediary between the PLC under test and the testing system. It mediates the interaction by receiving PLC commands, processing them through simulated control logic, and generating appropriate feedback signals, thereby enabling loop-locked verification while keeping the testing setup manageable
2Reliability
If manual intervention simulation is added to achieve closed-loop verification, then test reliability is improved, but ease of operation decreases
Solution Approach 1:
The virtual device is designed to automatically simulate manual intervention actions that would normally require operator input. The system self-services by programmatically generating and processing manual operation commands, eliminating the need for actual manual intervention during testing while maintaining the realism of closed-loop verification scenarios
3Manufacturing precision
If fault injection testing is implemented, then manufacturing precision of test cases is improved, but time consumption increases
Solution Approach 1:
The system pre-configures multiple fault injection scenarios and test cases before actual testing begins. Common fault conditions, error states, and abnormal operating conditions are predetermined and stored in the virtual device, allowing rapid execution of precise fault injection tests without time-consuming setup during the testing phase
Data Source
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AI summary
The present application relates to a PLC testing system and method, and belongs to the technical field of testing. The PLC testing system includes: a virtual device simulating a field real device, a testing tool and a PLC device. The testing tool is configured to start a preset test case to inject a fault into the virtual device. The PLC device is configured to execute a preset fault processing logic when receiving a fault signal produced by the virtual device simulating a field fault according to the injected fault, the preset fault processing logic including sending alarm information to the virtual device. The testing tool is further configured to test whether the fault processing logic of the PLC is normal by detecting whether the alarm information forwarded by the virtual device meets the expectation of injecting the fault by the preset test case. The virtual device is used to simulate the field real device, such that the corresponding fault signal can be produced by simulating the field fault and sent to the PLC device, and the PLC device executes the corresponding fault processing logic, so as to achieve the closed-loop effect, thereby improving the test reliability.