Cross-Controller Ladder Display for Secure PLC Debugging
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Solution Overview
Problem
Conventional ladder program editors for PLCs cannot display or edit ladder programs from other apparatuses, and machine tool manufacturers are reluctant to share their preinstalled MTB ladder programs, limiting users' ability to refer to or debug user ladder programs.
Innovation Solution
A ladder display system that includes a first controller with a ladder program and a second controller for input/output processing, featuring an input/output signal table generating unit, an external reference execution unit, a ladder program output unit, and a ladder program display unit, allowing the display of at least a part of the first ladder program on the second controller, specifically in a pop-up area or different window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If machine tool manufacturers share their entire MTB ladder programs with users, then users can fully refer to and debug ladder programs, but manufacturers lose program security and control
Solution Approach 1:
The system extracts and transmits only the specific portion of the MTB ladder program that corresponds to the selected signal from the user ladder program, rather than sharing the entire program. This allows users to access necessary information while manufacturers maintain security over the complete program.
Solution Approach 2:
The system provides localized access to the MTB ladder program by displaying only the relevant section that corresponds to the selected signal. The display portion is locally targeted to match the user's debugging needs rather than providing universal access to the entire program.
2Ease of operation
If conventional ladder editors display only their own ladder programs, then program security is maintained, but users cannot refer to or debug MTB ladder programs from other apparatuses
Solution Approach 1:
The ladder editor is enhanced to perform multiple functions: it can display both the user's own ladder program and the corresponding portion of the MTB ladder program from another apparatus. This multi-functionality allows users to reference external programs while maintaining the original editor's core capabilities.
Solution Approach 2:
The system uses an intermediary mechanism (the ladder editor with external reference capability) that mediates between the user's debugging needs and the MTB ladder program stored in another apparatus. The editor acts as a bridge that retrieves and displays only the necessary external program portion.
3Loss of information
If the entire MTB ladder program is transmitted to the user's apparatus, then users can access all program information, but transmission data volume and processing complexity increase
Solution Approach 1:
The system extracts only the specific portion of the MTB ladder program that corresponds to the selected signal from the user ladder program. This extraction process significantly reduces the data transmission volume while maintaining the completeness of the necessary information for debugging.
Solution Approach 2:
Instead of transmitting the entire MTB ladder program (excessive action), the system transmits only the partial portion that is necessary for the user's debugging needs. This partial transmission approach optimizes data efficiency while meeting the user's information requirements.
Data Source
AI summary
A ladder display system includes: a first controller having a first ladder program; and a second controller having a second ladder program that performs input/output processing with the first ladder program. An input/output signal table generating unit generates an input/output signal table relating an input/output signal of the first ladder program to an input/output signal of the second ladder program. An external reference execution unit specifies a signal of the second ladder program and requests transmission of at least a part of the first ladder program. A ladder program output unit transmits at least a part of the first ladder program including a signal corresponding to the specified signal to the second controller. A ladder program display unit displays at least the part of the first ladder program output by the ladder program output unit on the second controller.