Bus Interrupt Exception Windows for Faster Industrial I/O Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing data communication bus systems, such as SILBUS, face limitations in noise immunity, channel capacity, and transmission distance, particularly in harsh industrial environments like long conveyor systems, leading to increased reaction times for control inputs and potential safety compromises.
Innovation Solution
A data communication bus protocol that incorporates a recurring global exception pulse or interrupt exception window, allowing for faster detection and response times by enabling transmitters to generate signals during designated windows, supporting a larger number of channels, and using twisted pair cables for improved noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard data communication bus protocol is used, then the system can support basic monitoring and control functions, but the reaction time for control inputs is too slow for safety-critical operations
Solution Approach 1:
The patent implements a periodic interrupt exception window protocol where transmitters can force interrupts at regular intervals (e.g., every 8th channel). This periodic mechanism ensures that safety-critical signals are detected within a bounded time frame, fundamentally improving reaction time compared to standard continuous scanning protocols.
Solution Approach 2:
The system pre-allocates specific interrupt exception windows in the communication cycle where safety-critical transmitters can force immediate attention. By preparing these dedicated time slots in advance, the system ensures that emergency signals are processed without waiting for the next regular scan cycle, reducing reaction time for safety operations.
2Quantity of substance
If the number of channels is increased to support more devices, then the system coverage is improved, but the transmission distance is limited by noise and signal degradation
Solution Approach 1:
The patent segments the communication protocol into distinct functional portions: normal data transmission channels and dedicated interrupt exception windows. This segmentation allows the system to handle more channels by efficiently organizing them into groups that can be scanned systematically, while the interrupt mechanism provides fast paths for critical signals regardless of channel position, effectively extending usable transmission distance.
Solution Approach 2:
The interrupt exception window acts as an intermediary mechanism between transmitters and the control system. When a transmitter needs immediate attention, it forces an interrupt through this dedicated channel, which mediates priority access to the control unit. This intermediary structure allows the system to maintain reliable communication over longer distances by providing multiple access paths rather than relying solely on sequential channel scanning.
3Quantity of substance
If the number of channels is increased to support more devices, then the system capacity is improved, but the complexity of the communication protocol increases
Solution Approach 1:
The protocol is segmented into distinct operational modes: normal data transmission and interrupt exception handling. Each mode has clearly defined rules and procedures, which simplifies the overall complexity compared to a single monolithic protocol handling all scenarios. The segmentation allows the system to support more channels by organizing them into manageable groups with predictable behavior patterns.
Solution Approach 2:
The periodic interrupt exception window creates a predictable, rhythmic structure to the communication protocol. Transmitters know when interrupt opportunities occur (e.g., every 8th channel), and the control system expects interrupts at these predetermined intervals. This periodicity reduces protocol complexity by eliminating the need for complex arbitration and priority resolution mechanisms that would be required in an aperiodic system.
4Reliability
If standard transmission methods are used, then the system can operate in harsh environments, but noise immunity is insufficient for industrial applications with variable frequency drives
Solution Approach 1:
The patent extracts the interrupt exception window mechanism from the normal data transmission flow, creating a separate, dedicated pathway for critical signals. This extraction isolates safety-critical communications from the noise and interference that affect general data transmission, improving noise immunity by providing a protected communication channel that is less susceptible to electrical interference from variable frequency drives and other industrial equipment.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An input/output (I/O) and control system for long distance communications and industrial applications having a bus and protocol for communications between field devices and a channel generator for monitoring and control of the field devices. The channel generator produces a pulse train such as an offset square wave with dual scan bus cycles having alternating A and B scan cycles that each comprise a plurality of channel windows assigned to the field devices. One or more channel windows in the A and B scan cycles has an exception interrupt window during which the control unit can detect a low level signal provided by a field device before its corresponding channel window in the dual scan bus cycle, thereby reducing system reaction time.