Two-Wire Bus Inbound Detection Using Dual Current Sensing
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Solution Overview
Problem
Existing dual line inbound detection systems on data communication buses face challenges with noise immunity and false detection issues, particularly in harsh industrial environments with long conveyor systems, where noise from variable frequency drives and limited channel capacity hinder accurate transmission detection.
Innovation Solution
A dual line inbound detection method using high side and low side current detectors with designated thresholds and averaging algorithms to differentiate between valid and noise-induced signals, ensuring reliable detection of inbound transmissions on a two-wire bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single line inbound detection is used on the data communication bus, then the device complexity is reduced, but the reliability of transmission detection deteriorates due to noise from variable frequency drives and limited channel capacity
Solution Approach 1:
The patent divides the single detection line into two separate detection lines (first detection line and second detection line), each monitoring different aspects of the signal. This segmentation allows the system to cross-validate signals and distinguish true transmissions from noise, thereby improving reliability without requiring a completely complex new system architecture
Solution Approach 2:
The patent transitions from single-line detection to dual-line detection, adding an additional dimension to the detection process. By monitoring both the first detection line and second detection line simultaneously, the system can compare signals across dimensions to filter out noise from variable frequency drives and improve overall detection reliability
2Measurement precision
If threshold-based detection is used to identify inbound transmissions, then the detection speed is improved, but the measurement precision deteriorates due to false detection of noise as valid signals
Solution Approach 1:
The patent implements a feedback mechanism where the controller monitors signals on both detection lines and uses the combined information to validate inbound transmissions. The controller compares the first signal from the first detection line with the second signal from the second detection line, and only recognizes a transmission as valid when both lines indicate the same condition, thereby eliminating false detections while maintaining detection speed
Solution Approach 2:
The patent creates a composite detection system that combines two different detection lines with potentially different characteristics. By integrating the outputs of both lines, the system achieves superior signal discrimination capability, accurately distinguishing between valid transmissions and noise from variable frequency drives, thus improving measurement precision without sacrificing detection speed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly enhances noise immunity and reduces false detection, enabling accurate and reliable detection of inbound transmissions even in noisy conditions, thereby improving the reliability of conveyor monitoring and control systems.
Implementation Method 1
operating a high side current detector to detect current on the signal line
Implementation Method 2
operating a low side current detector to detect current on the common return line
Data Source
AI summary
An input/output (I/O) and control system for long distance communications and industrial applications is provided having a two wire bus and bus protocol for communications between field devices and a channel generator for monitoring and control of the field devices. The channel generator produces an offset square wave on the bus, and sends a synchronization pulse of selected duration at the start of each bus scan cycle in a pulse train cycle to reset counters in the field devices before the bus scan cycle is repeated, to ensure field devices are synchronized, transmitters transmit on the correct channel, and receivers sample the pulse cycle at the correct time. High side and low side current detectors for respective ones of the two wires of the bus and an algorithm are provided to improve detection of valid inbound transmissions by the channel generator for increased noise immunity.