Bus Coupler Impedance Converter for Field Device Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bus couplers in explosion protection areas face challenges in providing comprehensive diagnosis options for individual transmission lines and field devices, as interference couplings and complex circuits are required to diagnose noise, jitter, and signal levels, making it difficult to assign diagnosis data to specific devices.
Innovation Solution
A bus coupler with a transmit-receive unit featuring an impedance converter, a terminating resistor, and a controllable reference voltage source, which forms a current-limiting and terminating resistor, allowing for separate diagnosis of each transmission line and field device, and includes a switching mechanism to prevent interference couplings by shutting off non-connected devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bus coupler is used in explosion protection areas with complex interference coupling circuits for diagnosis, then diagnosis capability is improved, but device complexity increases and makes it difficult to assign diagnosis data to specific devices
Solution Approach 1:
The bus coupler is divided into separate transmit-receive units, each with its own impedance converter and terminating resistor. Each unit can be independently diagnosed through its dedicated field device output connection, allowing diagnosis data to be clearly assigned to specific devices without complex interference coupling circuits.
Solution Approach 2:
The impedance converter is extracted as a separate functional block within each transmit-receive unit, with its own controllable reference voltage source. This extraction allows for simplified individual diagnosis of each unit's performance without requiring complex system-wide interference coupling analysis.
2Adaptability or versatility
If multiple field devices are connected to the bus coupler, then system functionality is improved, but interference couplings between devices increase making diagnosis difficult
Solution Approach 1:
Each field device connection has its own dedicated transmit-receive unit with separate impedance converter and terminating resistor. This segmentation isolates each device's electrical characteristics, allowing individual diagnosis without interference from other connected devices.
Solution Approach 2:
The impedance converter acts as an intermediary between the superordinate bus system and individual field devices. It provides a virtual ground point that electrically isolates each device connection, preventing interference couplings while maintaining system functionality.
3Reliability
If current limiting is implemented in explosion protection areas, then safety is improved, but additional current-limiting resistors increase device complexity
Solution Approach 1:
The terminating resistor at the field device output is combined with the impedance converter's output stage to simultaneously provide both impedance matching and current limiting functions. This merging eliminates the need for separate current-limiting resistors while maintaining safety in explosion protection areas.
Solution Approach 2:
The terminating resistor serves multiple functions: it provides impedance matching for the transmission line, limits current for explosion protection, and enables voltage drop measurements for diagnosis. This multi-functionality reduces overall device complexity while improving safety.
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
Enables comprehensive diagnosis and interference-free communication by setting current limits and shutting off non-connected field devices, reducing interference and allowing for precise diagnosis of each transmission line and field device, thus enhancing diagnostic capabilities in explosion protection areas.
Implementation Method 1
the impedance converter is configured as an operational amplifier and planned such that its output impedance approaches zero and its output thus forms a virtual ground point
Implementation Method 2
a measuring means for determining a voltage drop is connected to the terminating resistor
Implementation Method 3
the control facility, which is configured to adjust the reference means with respect to a reference voltage for the second input via the control input to reduce a current flow through the terminating resistor and thus to obtain a current limit for the field device output
Data Source
AI summary
A bus coupler for coupling field devices to a superordinate bus system includes an impedance converter arranged in a series circuit with a terminating resistor between a signal input and a field device output to enable a comprehensive diagnosis option separately for each transmission line and the connected field device, wherein the terminating resistor assumes the function of a line terminating resistor and a current limitation, and where a controllable reference voltage source enables the maximum output current to be defined and the output shut off.