YOKOGAWA CENTUM CS 1000 Distributed Control System Control Function

YOKOGAWA CENTUM CS 1000 Distributed Control System Control Function

Product core positioning

CENTUM CS 1000 is a distributed control system developed by Yokogawa for small and medium-sized factories, with the core goal of reducing total cost of ownership (TCO) while balancing high functionality and maintainability. The design concept is to integrate the high-quality control functions of the CENTUM CS series that have been verified on site, strengthen the communication adaptation capabilities with various subsystems such as programmable logic controllers (PLCs), and solve the core pain points of small and medium-sized factories in control system deployment and maintenance through innovative technologies such as engineering process simplification, communication flexibility, and test virtualization.

System core function configuration

（1） Overall architecture of control function

The system control function is highly integrated into each field control station (FCS), with functional blocks as the core to build basic control applications, forming a complete functional system covering control, input/output, management and monitoring. The specific architecture is as follows:

Specific description of the core components of the functional hierarchy

The minimum unit of the core control component function block control algorithm, including basic components such as PID controller and selector, supporting modular assembly

Expansion control module covers various control blocks including regulation control block, sequence control block, SFC (Sequential Function Diagram) block, calculation block, and panel block, adapting to diverse control requirements

The auxiliary management function unit monitoring function is grouped by process unit management function blocks, greatly simplifying the control and monitoring operations of single process units

The status feedback function sequence message and alarm provide real-time feedback on the system's operating status, prompt abnormal information in a timely manner, and ensure operational safety

Universal control function universal switch provides standardized operation interface, suitable for conventional control scenarios

Input/output function process I/O implementation and signal input/output with general sensors and actuators, supporting data exchange of field devices

Input/output function communication I/O achieves signal transmission with external devices through universal communication interfaces such as RS-232C

（2） Reliability assurance design

The system continues the mature synchronous hot standby system of the CENTUM CS series, which is the core of ensuring control continuity

Working principle: The FCS operating system adopts a synchronous running mode between the primary and backup CPUs. When the primary CPU is working normally, the backup CPU synchronizes data in real time; When the main CPU stops due to a sudden failure, the backup CPU seamlessly takes over control tasks without interrupting control actions

Applicable scenarios: Especially suitable for batch production processes guided by sequence control, even during the switching process of duplex control processors, it can maintain control status continuously, avoiding production losses caused by downtime

Engineering Efficiency Optimization: FCS Template Technology

（1） Design background and pain points

The control application is composed of multiple functional blocks, but different functional blocks have significant differences in the internal resources (such as memory) and CPU load requirements of FCS. However, the memory resources of FCS are limited. If functional blocks are combined in an unordered manner, engineers need to have rich experience, estimate resource usage and CPU load in advance, and avoid exceeding the system's carrying capacity. This undoubtedly increases the complexity and threshold of engineering design.

（2） Core Design and Advantages of FCS Template

1. Template types and adaptation scenarios

Yokogawa provides users with three types of preset database templates that accurately match typical application scenarios for small and medium-sized factories:

Adjustment control template: adapted to parameter adjustment scenarios of continuous processes (such as temperature, pressure, flow rate adjustment)

Sequence control template: adapted to batch production scenarios executed according to fixed processes (such as chemical batching, product assembly)

Monitoring Template: Suitable for scenarios that only require data collection and status monitoring (such as device operation status monitoring)

2. Core technical features

Intelligent resource allocation: The template has a built-in optimized database configuration that automatically allocates FCS memory resources based on functional block types, ensuring optimal resource utilization

Strict load control: The preset configuration strictly controls the CPU load to not exceed the limit, eliminating the need for users to manually calculate and reducing the difficulty of engineering design

Ready to use: Users can directly select corresponding templates based on actual application scenarios, without the need to build functional block combinations from scratch, greatly reducing the project cycle

On site communication flexibility design: adaptable to diverse devices

In response to the industry pain points of dispersed on-site control equipment, diverse data types, and inconsistent communication interfaces and protocols, CENTUM CS 1000 achieves flexible adaptation through two core designs:

（1） Separation of communication function and control application

1. Architecture design logic

Data storage isolation: External data obtained through communication is uniformly stored in a separate "communication I/O area", which is divided into sub areas according to subsystems (such as subsystem 1 communication I/O area, subsystem 2 communication I/O area)

Data access method: Control the control block in the application to access the data in the communication I/O area (such as% WW0100. PV) through "relative address" or "user-defined tag", without paying attention to the physical source of the data

Automatic data type recognition: The system automatically recognizes the type of each data item (integer, floating point, etc.) in the communication I/O area, and users do not need to manually set the data type when configuring control applications

2. Core advantages

Protocol independence: When the communication protocol is changed, only the communication module configuration needs to be adjusted without modifying the control application, reducing system modification and maintenance costs

Reduce coupling: control logic and communication logic are decoupled to improve system stability and reduce the impact of single module failure on the overall system

（2） C programming language adapted to multiple protocols

1. Protocol adaptation plan

Common protocols: Yokogawa has developed ready-made communication packages for mainstream communication protocols in the industrial field, which users can directly choose and quickly complete equipment docking

Special protocol: For niche or customized protocols, support users to develop communication programs through C language coding to achieve personalized adaptation

2. Communication data flow

On site equipment/subsystems are connected to FCS through a common communication interface

Communication program (ready-made communication package or user C language program) retrieves data and stores it in the communication I/O area

Control applications to access communication I/O areas through addresses or labels to achieve data exchange

Control instructions are transmitted in reverse to on-site devices/subsystems through the same path

Innovative virtual testing function: deep analysis of simulator system

（1） Design Objective

Without the need to build a complete physical FCS hardware environment, the design, testing, and verification of control applications can be completed solely through a personal computer (PC), reducing the cost of building engineering environments and improving project implementation efficiency.

（2） FCS Simulator: Core Virtual Testing Tool

1. Basic configuration

Operating environment: Windows NT operating system

Run mode: Run as an independent process, read the control application definition file generated by the engineering function

2. Core functions

Control action simulation: Fully replicate the control logic and execution process of actual FCS to ensure that test results are consistent with actual operation

Communication mechanism: Through "simulating internal VLnet communication", interaction with PC side operation monitoring function (HIS function) and testing function is achieved. The operation logic is completely the same as connecting to the actual FCS, and users do not need to learn new operation methods separately

3. Internal operating mechanism

Modular design: Each FCS functional task (such as control tasks, communication tasks, trend tasks) is encapsulated as a dynamic link library (DLL) and loaded in thread form during runtime

Kernel adaptation: Built in FCS kernel simulation function (also encapsulated as DLL), its interface is completely consistent with the actual FCS kernel, ensuring the reusability of task source code and guaranteeing functional equivalence

Thread scheduling: After a thread calls the kernel simulation function, it triggers scheduling (scheduling point), and switches threads through the "suspend/resume" command of the Win32 API - the current thread first resumes other suspended threads, and then suspends itself to ensure the orderly execution of multitasking

Interrupt handling: Independent interrupt threads use Windows messages as trigger signals to pause the current task, execute interrupt handling, and resume scheduling after receiving the message, ensuring real-time interrupt response

（3） Inter Station Communication Simulator: Multi FCS Collaborative Testing Tool

1. Original design intention

Support control application testing that requires data interaction between multiple FCS, enabling multi-user parallel system engineering and improving overall design efficiency.

2. Working principle

Data reception: Receive all communication data packets sent by the FCS simulator to other FCS

Data processing:

When receiving data setting commands, save the corresponding request values

When receiving a data read command, return the preset response value

Interactive interface: Support users to view saved request values and set response values through a graphical user interface (GUI), with intuitive and convenient operation

3. Core advantages

Without the need to deploy multiple physical or virtual FCS, cross FCS control application testing can be completed without increasing the existing CPU load, significantly reducing the cost and complexity of multi system collaborative testing.

（4） Overall collaborative process of simulator system

Engineers design control applications through PC engineering functions and generate control application definition files

The FCS simulator loads the definition file and simulates the actual execution of control actions by FCS

If multiple FCS data interactions are involved, start the inter station communication simulator to simulate the response logic of other FCS

The operation monitoring function and testing function simulate internal VLnet communication and interact with the FCS simulator to conduct application testing

After the testing is completed, the control application can be directly deployed to the actual FCS without additional modifications

Core values and future prospects of the system

（1） Summary of Core Values

Specific manifestation of value dimension

Cost optimization: 1. Virtual testing function reduces the cost of building engineering environments; 2. FCS templates simplify the design process and reduce labor costs; 3. Communication and control separation design reduces maintenance costs

Efficiency improvement 1. Template based engineering design shortens project cycle; 2. Multi user parallel testing improves project implementation efficiency; 3. Control the application of "one-time design, two-way deployment" (simulator and actual FCS) to reduce repetitive work

Strong adaptability: 1. Supports multiple communication interfaces and protocols, and adapts to dispersed and diverse on-site devices; 2. Three types of FCS templates cover mainstream application scenarios in small and medium-sized factories

High reliability synchronous hot standby system ensures uninterrupted control in case of CPU failure and adapts to critical scenarios such as mass production

（2） Future Technology Outlook

The document proposes that future control systems need to have open interfaces and cross platform features that are consistent with human-machine interfaces and engineering functions. The simulator technology and enhanced on-site communication capabilities of CENTUM CS 1000 lay the foundation for subsequent technological development

Expansion direction 1: Develop FCS software running on PC to achieve direct control of industrial processes through PC

Expansion direction 2: Develop gateway functions based on existing communication interfaces to achieve interconnectivity among multiple systems

Expansion direction 3: Upgrade the enhanced on-site communication function to a high reliability gateway, adapting to more complex industrial network architectures

Applicable scenarios and industry adaptation

Target scenarios: Continuous process control, batch production sequence control, equipment status monitoring, and other scenarios for small and medium-sized factories

Applicable industries: chemical, pharmaceutical, food and beverage, small-scale electricity, building materials, etc. industries that are sensitive to control system costs, have diverse equipment types, and limited engineering resources

Core adaptation requirements: Application scenarios that require simplification of engineering design, reduction of maintenance costs, adaptation to diverse field devices, and certain requirements for control continuity