Dual-Controller Field Bus Control for Continuous Slave Operation
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Solution Overview
Problem
In factory automation systems, control for multiple slave devices is halted when a controller fails or is temporarily stopped, leading to production defects and reduced productivity.
Innovation Solution
A dual-controller configuration where each controller can generate and transmit control frames, with mutual operation confirmation through a data communication network, ensuring continuous control even if one controller fails or is temporarily stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single controller is used for controlling slave devices, then the device complexity is low, but the reliability of control is poor when the controller fails or is temporarily stopped
Solution Approach 1:
The system divides the controller function into two separate controller devices (first controller and second controller), each capable of independently controlling the slave devices. This segmentation allows the system to maintain control functionality even when one controller fails or is temporarily stopped, thereby improving reliability without significantly increasing overall system complexity.
Solution Approach 2:
The system changes the operational state parameter of the controllers by switching between a normal state (where the first controller controls slave devices) and a swapped state (where the second controller controls slave devices). This parameter change enables seamless takeover control, ensuring control continuity when one controller is unavailable.
2Reliability
If a dual-controller configuration is implemented for continuous control, then the reliability of control is improved, but the device complexity increases
Solution Approach 1:
The system merges the control capability into both the first controller and the second controller, making them functionally equivalent and interchangeable. Both controllers have the ability to generate control frames and control the same slave devices, which simplifies the overall system architecture compared to a master-slave controller configuration and reduces the complexity increase.
Solution Approach 2:
The controllers exchange operation confirmation signals through a communication network to monitor each other's status. This feedback mechanism enables automatic detection of controller failures or temporary stops and triggers appropriate takeover actions, ensuring reliable control continuity while maintaining manageable system complexity through automated monitoring.
3Ease of repair
If the controller is stopped for firmware rewriting or maintenance, then the controller can be updated, but the control for slave devices is interrupted
Solution Approach 1:
The system prepares a standby controller (second controller) in advance that is capable of taking over control functions. When the first controller needs to be stopped for firmware rewriting or maintenance, the second controller is already positioned and configured to immediately assume control, eliminating any interruption in slave device operation and maintaining productivity during maintenance activities.
Data Source
Figure 1~2
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Figure 5
AI summary
This control system (1) is provided with a plurality of slave devices (21, 22, 23) and controllers (11, 12). The controller (11) is connected to one end of a field bus which includes the plurality of slave devices (21, 22, 23) that is linearly connected, and the controller (12) is connected to the other end of the field bus through a communication cable. The controllers (11, 12) are provided with a CPU (101) and a transception part (102). One of the controllers (11, 12) generates a control frame with the CPU (101) and transmits this from the transception part (102), and the other of the controllers performs a loop communication of the control frame by the transception part (102).