I/O Device Synchronous Execution for Fieldbus Control Modules

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Solution Overview

Problem

In process control systems, the execution of control modules with function blocks split between a controller and Fieldbus devices introduces significant delays due to asynchronous execution, as communications between the controller and Fieldbus devices must be managed outside the Fieldbus segment schedule, leading to suboptimal execution rates.

Innovation Solution

An input/output device is configured to support execution of function blocks not supported by Fieldbus devices, allowing these blocks to participate synchronously in the Fieldbus segment schedule, and an apparatus/method automatically assigns function blocks to either Fieldbus devices or an I/O device for synchronous execution, ensuring all critical blocks execute within a single macrocycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If function blocks are placed in a controller connected to the Fieldbus segment via an input/output device, then the control module can be implemented with mixed architecture, but the execution rate is slowed down due to asynchronous execution

Engineering Contradiction:

Improvecontrol module architectureVSAvoidexecution rate

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The input/output device is configured to execute function blocks and participate directly in the Fieldbus segment communication schedule, acting as an intermediary that bridges the controller and Fieldbus devices while maintaining synchronous execution. This allows the I/O device to manage communications within the Fieldbus segment schedule rather than outside it, eliminating the asynchronous execution penalty.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The input/output device is enhanced to perform multiple functions: it not only manages communications between the controller and Fieldbus devices but also executes function blocks directly as part of the Fieldbus segment schedule. This multi-functionality allows the I/O device to maintain synchronous execution while supporting mixed architecture control modules.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If function blocks are executed asynchronously in the controller, then communications can be managed flexibly, but significant delays are introduced into the control loop

Engineering Contradiction:

Improvecommunication management flexibilityVSAvoidcontrol loop delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The input/output device serves as an intermediary that executes function blocks within the Fieldbus segment schedule, eliminating the need for asynchronous communication management. By participating directly in the synchronous schedule, the I/O device removes the time delays associated with asynchronous execution while maintaining communication management capabilities.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If all function blocks are placed in Fieldbus devices, then synchronous execution is achieved, but not all function blocks are supported by the available Fieldbus devices

Engineering Contradiction:

Improveexecution rateVSAvoidfunction block support

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The input/output device is enhanced with the capability to execute function blocks, making it a universal platform that can handle both communications and control functions. This allows function blocks that are not supported by Fieldbus devices to be executed in the I/O device while maintaining synchronous execution within the Fieldbus segment schedule.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control module is segmented into function blocks that can be distributed across Fieldbus devices and the input/output device. This segmentation allows each function block to be placed in the most appropriate location while maintaining overall synchronous execution, resolving the limitation of Fieldbus device functionality.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8005553B2Automatic configuration of synchronous block execution for control modules run in fieldbus networks

Publication Date: 2011.08.23 FISHER ROSEMOUNT SYST INC

AI summary

A method or apparatus automatically configures a control module for synchronous execution on a Fieldbus segment of a process control network by determining if all of the critical function blocks of a particular control module can be assigned to FOUNDATION® Fieldbus field devices or to the I/O device associated with a particular Fieldbus segment. If so, the method or apparatus automatically assigns the function blocks of the control module, which would otherwise be scheduled to execute in a controller, to the I/O device for the Fieldbus segment. This technique enables all of the critical or necessary function blocks within the control module to execute in one macrocycle of the Fieldbus segment, thereby executing synchronously on a Fieldbus segment. This operation, in turn, increases the overall execution rate of the control module with respect to control modules that have function blocks split between a controller and field devices on a Fieldbus segment, which has been the traditional manner of configuring control modules implemented using devices on a Fieldbus segment.