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A Graphical Model for Interactive Distributed Control (SAE J2356-2007)
Introduction to the Interactive Distributed Control Model
The SAE J2356 standard, originally issued in 1997 and cancelled in 2007, provides an architectural model for Distributed Embedded Systems (DES) and a graphical method for representing events, activities, and transactions to support Interactive Distributed Control (IDC). This model is crucial for analyzing timing characteristics in high-speed multiplexed networks used for vehicle motion control, such as engine, braking, traction, and speed control. The document was cancelled to redirect efforts to a new recommended practice, but its foundational concepts remain valuable.
🔍 Engineering Design Insight: The graphical model enables designers to visualize functional operation and timing before system realization, addressing critical questions about network bandwidth and processing power early in the design phase.
Key Elements and Timing Analysis
The model consists of five essential building blocks: Input, Control, Output, Transmit, and Receive. These blocks can construct any distributed function.
| Building Block | Function |
|---|---|
| Input | Represents interconnection of input device or signal to control element |
| Control | Implements algorithm for translating input to output, defining system behavior |
| Output | Converts control data to system output responses |
| Transmit | Accepts data from input/control and sends it onto the network |
| Receive | Accepts network data and routes it to appropriate control or output element |
Process models for input, output, control, transmit, and receive processes define timing characteristics. Timing analysis uses three diagram formats: event, activity, and transaction diagrams. These help evaluate network speed and microcomputer processing power.
🛠️ Practical Consideration: Partitioning of functions across module boundaries must be based on intended control architecture, software architecture, and expected data rates to avoid bottlenecks.
Frequently Asked Questions
- What is Interactive Distributed Control?
Interactive Distributed Control (IDC) is an information and control transfer strategy that uses a network of microcomputer-based modules to support a collection of high-speed distributed functions. - What are the five essential building blocks of the IDC graphical model?
The building blocks are Input, Control, Output, Transmit, and Receive. They form the architectural elements of any distributed function. - Why was SAE J2356 cancelled?
It was cancelled in 2007 to redirect efforts from the SAE J2356 Information Report to a new recommended practice that would reuse portions of the document. - How does timing analysis benefit IDC system design?
Timing analysis helps answer whether network bandwidth and speed are sufficient for all intended high-speed functions, and determines the microcomputer processing power needed for each module.
