Method of controlling connection of fail-safe resistors to ends of communication lines in differential voltage communication and communication device employing the method
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Solution Overview
Problem
In differential voltage communication methods like RS-485 and Modbus, unstable voltage levels between communication lines can lead to communication failures, particularly when multiple slave devices are connected in reverse polarity, causing errors and disrupting data transmission.
Innovation Solution
A control method that employs fail-safe resistors, where a master device monitors the voltage between communication lines and connects pull-up and pull-down resistors strategically to maintain a stable voltage level by controlling switches connected to these resistors, ensuring that only one pull-up resistor is connected to one communication line and one pull-down resistor is connected to the other, thereby preventing communication failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fail-safe resistors are connected to both master device and slave devices, then communication reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic connection control of fail-safe resistors through switches that are controlled based on communication status detection. The master device detects communication failures and dynamically connects or disconnects the fail-safe resistors accordingly, transforming a static configuration into a dynamic adaptive system that maintains reliability while reducing complexity.
Solution Approach 2:
The patent pre-configures fail-safe resistors and switches in both master and slave devices, but keeps them disconnected during normal operation. When communication failure is detected, the system activates the pre-configured components to restore communication. This preliminary preparation allows rapid response to failures without permanently increasing system complexity.
2Reliability
If voltage level is strictly maintained using fail-safe resistors, then communication stability is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic monitoring of communication status and dynamically activates fail-safe resistors only when communication failures are detected. Instead of continuous operation, the system uses periodic detection and intermittent activation, reducing energy consumption while maintaining communication stability when needed.
Solution Approach 2:
The system dynamically adjusts the connection state of fail-safe resistors based on real-time communication status. During normal operation, resistors remain disconnected to minimize energy consumption. When instability is detected, the resistors are dynamically connected to restore voltage levels, creating an adaptive energy-efficient system.
3Adaptability or versatility
If multiple slave devices are connected to extend communication network, then adaptability is improved, but voltage stability deteriorates
Solution Approach 1:
The patent introduces fail-safe resistors as intermediary components between communication devices. These resistors act as mediators that stabilize voltage levels on the communication bus when multiple slave devices are connected, preventing voltage instability while allowing network expansion. The resistors provide a reference level that maintains signal integrity across extended networks.
Solution Approach 2:
The system dynamically connects fail-safe resistors when communication instability is detected in extended networks with multiple slave devices. This dynamic adaptation allows the network to maintain stability when expanded, as the resistors are activated only when needed to counteract the voltage instability caused by additional devices.
Data Source
AI summary
An air conditioner device includes a first and second communication lines configured to provide communications between a first slave device and a master device through a voltage difference. The master device having a voltage sensor configured to sense a voltage between the ends of the two communication lines and a processor configured to, based on the sensed voltage being less than or equal to a preset voltage, transmit a command to perform connection control such that one of a first resistor on a side of the master device and a third resistor on a side of the first slave device serves as a pull-up resistor, and to perform connection control such that at least one of a second resistor on a side of the master device and a fourth resistor on a side of the first slave device serves as a pull-down resistor.