Digital control system

Abstract

A digital control system, comprising a master control module, n communication modules, and a plurality of I / O modules of the same type, where n is an integer greater than 1. The master control module is connected to the n communication modules in a serial communication mode, the serial communication between the master control module and each communication module is implemented by means of a built-in field programmable gate array (FPGA) thereof, and the serial communication is implemented on the basis of a gigabit serializer / deserializer (Serdes). Each communication module is connected to a plurality of links operating in a parallel manner, each link is connected to a plurality of I / O modules, and each communication module uses a polling mode to manage communication of the I / O modules connected thereto, thereby solving the problem of relatively long loop control cycles of digital control systems under large-scale configuration.

Description

A digital control system

[0001] This application claims priority to Chinese Patent Application No. 2024116629657, filed on November 20, 2024, entitled “A Digital Control System”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of automation control technology, and in particular to a digital control system. Background Technology

[0003] DCS (Digital Control System) is an automation control system widely used in the industrial field. With its highly integrated digital technology, it enables precise monitoring and control of various industrial equipment in large industrial facilities such as nuclear power plants.

[0004] Loop control is a key component of DCS, encompassing the complete control process from data (including analog and digital signals) acquisition and logic operations to command output. The length of the loop control cycle directly reflects the sensitivity and accuracy of the DCS in controlling industrial equipment.

[0005] With the surge in the number of I / O modules, the loop control cycle has also been forced to lengthen, which reduces the real-time performance and control accuracy of the DCS. Summary of the Invention

[0006] In view of the above problems, this application provides a DCS to solve the problem of long loop control cycles in large-scale DCS configurations. The specific solution is as follows:

[0007] This application provides a DCS, including: a main control module, n communication modules, and multiple I / O modules of the same type; n is an integer greater than 1;

[0008] The main control module is connected to n communication modules via serial communication; the serial communication between the main control module and each communication module is implemented through their respective built-in field-programmable gate arrays (FPGAs), and the serial communication is based on gigabit serializer / deserializer (Serdes) technology.

[0009] Each communication module is connected to multiple links that operate in parallel. Each link is connected to multiple I / O modules. Each communication module manages the communication with each I / O module connected to it using a polling method.

[0010] In one possible implementation, the gigabit serializer / deserializer SerDes technology converts electrical signals into optical signals using a small, pluggable SFP module, and then uses optical fiber as the transmission medium.

[0011] In one possible implementation, the main control module and each communication module have built-in error checking and correction (ECC) modules.

[0012] In one possible implementation, the polling method is the ECC polling method.

[0013] In one possible implementation, the main control module combines a central processing unit (CPU) with an FPGA, where data acquisition tasks are run by the FPGA and logic operation tasks are executed by the CPU.

[0014] In one possible implementation, communication between the communication module and the I / O module is based on the RS485 protocol.

[0015] In one possible implementation, the plurality of I / O modules of the same type are n×m×x I / O modules of the same type, each communication module is connected to m links that operate in parallel, and each link is connected to x I / O modules, where m and x are both integers greater than 1.

[0016] In one possible implementation, the n×m×x I / O modules of the same type are n×m×x digital I / O modules, and the number of channels of the digital I / O modules is 16, n=8, m=6, x=10;

[0017] Alternatively, the n×m×x I / O modules of the same type can be n×m×x analog I / O modules, with each analog I / O module having 8 channels, n=8, m=6, and x=10.

[0018] In one possible implementation, the communication time of each communication module does not exceed 1 millisecond, the processing cycle of the main control module for logical operations is set to 10 milliseconds, and the communication time of each I / O module is limited to no more than 2 milliseconds.

[0019] In one possible implementation, the DCS is a DCS for nuclear power plants.

[0020] By employing the above technical solution, the DCS provided in this application adopts a two-layer network structure to optimize the communication between the main control module and the I / O modules. In the first layer, the main control module uses a built-in FPGA and gigabit SerDes technology to achieve serial communication with n communication modules, ensuring fast and stable communication. In the second layer, the communication modules manage the communication of I / O modules on their connected parallel links in a polling manner, effectively avoiding frame conflicts. Thus, an ideal loop control cycle is maintained, ensuring efficient operation even when faced with a large number of I / O modules. Attached Figure Description

[0021] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0022] Figure 1 is a schematic diagram of a loop control flow of a DCS provided in this application;

[0023] Figure 2 is a schematic diagram of a DCS provided in this application;

[0024] Figure 3 is a schematic diagram of the structure of a DCS based on 480 digital I / O modules provided in this application;

[0025] Figure 4 is a schematic diagram of the time distribution of a loop control cycle provided in this application;

[0026] Figure 5 is a schematic diagram of the structure of a DCS based on 480 analog I / O modules provided in this application. Detailed Implementation

[0027] In order to ensure the accuracy of the citations and the fluency of reading, the key technical terms, abbreviations or acronyms used in the text are summarized and explained as follows:

[0028] DCS: Digital Control System;

[0029] I / O: Input / Output;

[0030] Serdes: Serializer / Deserializer;

[0031] SFP: Small Form-factor Pluggable;

[0032] FPGA: Field-Programmable Gate Array;

[0033] CPU: Central Processing Unit;

[0034] ECC: Error Checking and Correcting;

[0035] RS485: Electronic Industry Association (EIA) Standard RS-485;

[0036] A / D: Analog to Digital conversion;

[0037] AI: Analog Input;

[0038] TC: Temperature Controller;

[0039] RTD: Resistance Temperature Detector;

[0040] DI: Digital Input.

[0041] DCS, as an automation control system widely used in industrial fields, plays a crucial role in large-scale industrial facilities such as nuclear power plants. Leveraging highly integrated digital technology, it enables precise monitoring and control of various industrial equipment within these facilities, providing a solid foundation for their safe and efficient operation.

[0042] Loop control is a key component of DCS, encompassing the complete control flow from data (including analog and digital signals) acquisition and logic operations to command output, as shown in Figure 1. In this control flow, the DCS can rapidly respond to various state changes of industrial equipment and perform fast and accurate calculations and judgments based on preset logic algorithms. Subsequently, the DCS generates corresponding control commands, which are then used by actuators to precisely control the industrial equipment.

[0043] The length of the loop control cycle directly reflects the sensitivity and accuracy of the DCS in controlling industrial equipment. An efficient DCS can significantly shorten the loop control cycle, ensuring that industrial equipment maintains optimal operating conditions under various circumstances. This is of great significance for improving the safety, stability, and economy of large industrial facilities such as nuclear power plants. Especially when facing various emergencies that may occur in nuclear power plants, the sensitive response and accurate control of the DCS are particularly important. For example, in emergencies such as abnormal increases in reactor power or cooling system failures, the DCS can quickly identify and take corresponding control measures, effectively preventing further deterioration of the situation. This capability not only protects nuclear power plant equipment from damage but also ensures the safety of nuclear power plant personnel and the surrounding public.

[0044] Loop control employs a collaborative approach between the master control module and I / O modules. The I / O modules handle data acquisition and output, while the master control module handles logic operations. In traditional DCS, communication between the master control module and I / O modules uses a single-layer network structure, where all I / O modules share the same bus network. The master control module acquires data from the I / O modules via a polling mechanism, with the bus rate typically maintained in the range of several megabytes per second. After acquiring I / O data, the master control module performs logic operations, with the processing cycle (referred to as the operation cycle) generally set at 50 milliseconds. However, with the surge in the number of I / O modules, the master control module consumes a significant amount of time polling each I / O module and acquiring data. At this point, the polling cycle of the master control module becomes a key factor limiting the length of the loop control cycle. Furthermore, with the increasing number of I / O modules, the originally set 50-millisecond operation cycle may no longer be guaranteed, further extending the loop control cycle and reducing the real-time performance and control accuracy of the DCS.

[0045] Taking a nuclear power plant DCS as an example, a typical nuclear power plant DCS has approximately 700 physical points, of which about 500 are digital I / O points and about 200 are analog I / O points. The digital I / O modules and analog I / O modules are polled separately. After actual measurement, it was found that the loop control cycle of analog I / O in this nuclear power plant DCS can reach up to about 500 milliseconds (i.e., the loop control cycle of the last polled analog I / O module can reach about 500 milliseconds), and the loop control cycle of digital I / O can reach up to about 400 milliseconds (i.e., the loop control cycle of the last polled digital I / O module can reach about 400 milliseconds).

[0046] However, when the scale of the DCS used in the nuclear power plant is expanded, for example, when its switching quantity is expanded to 7680 points, assuming that the number of channels of the switching I / O module is 16, the DCS used in the nuclear power plant will require a total of 480 switching I / O modules (7680 points / 16 channels = 480). The main control module needs to obtain data from 480 switching I / O modules in each polling cycle. Assuming that the polling cycle of the main control module is 1 millisecond, then the data acquisition part will take 480 milliseconds (480 modules × 1 millisecond / module = 480 milliseconds). Adding the time taken by the logic operation and instruction output, the loop control cycle of the switching quantity will inevitably exceed 500 milliseconds, resulting in a long loop control cycle of the switching quantity.

[0047] To address the issue of long loop control cycles in traditional DCS systems under large-scale configurations, this application provides a DCS that employs a two-layer network structure to optimize communication between the main control module and the I / O modules. In the first-layer network structure, the main control module utilizes a built-in FPGA and gigabit SerDes technology to achieve serial communication with n communication modules, ensuring fast and stable communication. In the second-layer network structure, the communication modules manage the communication of I / O modules on their connected parallel links using a polling method, effectively avoiding frame conflicts. Thus, an ideal loop control cycle is maintained, ensuring efficient operation even with a large number of I / O modules.

[0048] The following detailed description, with reference to the accompanying drawings, illustrates a DCS provided by an embodiment of this application. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0049] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0050] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the embodiments of this application, “one or more” means one, two, or more; “and / or” describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0051] Referring to Figure 2, an embodiment of the DCS provided in this application includes: a main control module, n (n≥2) communication modules, and n×m×x (m≥2, x≥2) I / O modules of the same type (e.g., all of them are digital I / O modules or all of them are analog I / O modules). Figure 2 is only illustrated with n=8, m=6, x=10 as an example.

[0052] The main control module is connected to n communication modules via serial communication; the serial communication between the main control module and each communication module is implemented through its built-in FPGA, and this serial communication is based on gigabit SerDes technology.

[0053] Each communication module is connected to m links that operate in parallel. Each link is connected to x I / O modules. Each communication module uses a polling method to manage the communication of each I / O module connected to it.

[0054] The working principle of the DCS shown in Figure 2 will be described in detail below:

[0055] The communication module acts as a bridge connecting the main control module and the I / O modules, responsible for data reception, processing, and forwarding. The main control module exchanges data with n communication modules sequentially through a serial communication link. Serial communication is a data communication method in which data is transmitted serially (i.e., bit by bit). It is widely used in digital communication systems due to its advantages such as reducing the number of connection lines, reducing electromagnetic interference, and saving power. In the serial communication link, the main control module, as the initiator and controller of communication, uses a serial communication protocol to send and receive data with each communication module one by one according to a specific timing and format. Each communication module occupies a unique, sequential position in the serial communication link, ensuring that data is transmitted accurately and without error between the main control module and each communication module in a predetermined order.

[0056] In terms of communication technology, the network connection between the main control module and each communication module is based on gigabit SerDes technology. SerDes is short for Serializer and Deserializer, a high-speed serial communication technology that can convert multiple low-speed parallel signals into high-speed serial signals for transmission, and then restore the high-speed serial signals to low-speed parallel signals at the receiving end. Gigabit SerDes refers to its support for gigabit-rate high-speed serial communication, ensuring high-speed, low-latency data transmission.

[0057] In one possible implementation, gigabit SerDes can convert electrical signals into optical signals using an SFP module, and then utilize optical fiber as the transmission medium. An SFP module is an interface standard for high-speed data transmission. In this embodiment, the SFP module is used to convert the electrical signals generated by gigabit SerDes into optical signals for long-distance, low-loss transmission over optical fiber, ensuring high-speed and stable data transmission.

[0058] On the communication hardware platform, both the main controller and the communication module contain FPGAs, and serial communication between them is achieved through the built-in FPGA. An FPGA is a highly flexible digital circuit that can be programmed to implement various complex logic functions. It has significant advantages in high parallel computing power and low latency, specifically:

[0059] 1) FPGA contains a large number of logic units and programmable connections, allowing multiple computing tasks to be executed simultaneously. It has a high parallel computing capability, which gives FPGA a significant speed advantage when processing computationally intensive tasks such as image processing and signal processing.

[0060] 2) The hardware-based architecture of FPGAs allows signals to be transmitted directly in the hardware circuitry, greatly reducing processing latency. Compared to software-based processors (such as CPUs), FPGAs can complete data processing in nanoseconds with almost no software-level latency. This low-latency characteristic gives FPGAs a significant advantage in applications requiring high real-time performance.

[0061] Based on this, in the embodiments of this application, the FPGA is used to implement the logic functions of the two ends of the communication (i.e., the main control module and the communication module), thereby ensuring the high speed and stability of the communication.

[0062] In summary, the DCS provided in this application adopts a two-layer network structure to optimize the communication between the main control module and the I / O module. The first layer network structure is the communication between the main control module and the communication module, and the second layer network structure is the communication between the communication module and the I / O module. In the first layer network structure, due to the adoption of advanced technologies such as gigabit SerDes and FPGA, the response time of the communication module is relatively short, and the communication process is stable and reliable.

[0063] In one possible implementation, both the main control module and the communication module have built-in ECC modules. The ECC module is used to detect and correct errors that may occur during data transmission. The ECC module has strong error correction capabilities, enabling it to detect and correct errors during data transmission, thereby ensuring data integrity and stability, which is crucial for reliable communication between the main control module and the communication module. Furthermore, by reducing the number of retransmissions caused by data transmission errors, ECC can indirectly improve communication efficiency.

[0064] It should be noted that the larger the total number of communication modules n, the larger the DCS scale, but the upper limit of the total number of communication modules n is constrained by the following factors:

[0065] 1) In serial communication, signals may be attenuated and interfered with during transmission. As the number of communication modules increases, signal quality may gradually decrease, leading to an increase in communication error rate. In order to ensure the reliability and stability of communication, the system needs to set a reasonable upper limit on the number of communication modules to avoid excessive degradation of signal quality.

[0066] 2) In serial communication, clock synchronization is a key factor in ensuring correct data transmission. As the number of communication modules increases, the difficulty and delay of clock synchronization will also increase accordingly. In order to maintain clock synchronization and reduce delay, the system also needs to limit the number of communication modules.

[0067] Taking a nuclear power plant's DCS with 7680 switching points and 16 channels for each switching I / O module, requiring a total of 480 switching I / O modules, as an example, the total number of communication modules can be set to n=8. In this case, assuming the longest communication time for each module does not exceed 1ms (when both the main control module and the communication modules have built-in ECC modules, this means the time from sending data to receiving data and passing ECC checks is no more than 1ms, determined by the processing power of the ECC module and the bandwidth of the communication network), when data is sent from the main control module and passes through 8 communication modules sequentially, each module introduces a certain communication delay. In the worst case (i.e., each communication module reaches its longest communication time), the total time from sending data from the main control module to receiving data and returning a response from the last communication module will be the sum of eight 1ms, i.e., 8ms. This is the acquisition response time of the last communication module.

[0068] In one possible implementation, the main control module combines a high-performance CPU with an FPGA, allowing the FPGA to handle data acquisition tasks while the CPU executes logic operations without interference, thus improving the overall system performance and stability. Therefore, the processing cycle for logic operations can be set to 10 milliseconds. With a CPU load of 50%, the maximum calculation time for the main control module is 15 milliseconds. The calculation process for 15 milliseconds is as follows:

[0069] Since signal transmission and computation occur in parallel, if a signal arrives just before the current computation cycle begins, it must wait for the next computation cycle to start. Assuming each computation cycle is 10 milliseconds, and the system operates at 50% load during the cycle in which it participates in the computation, it can complete the computation within 5 milliseconds. Therefore, the maximum time from signal arrival to its participation in and completion of the computation is: the 10 milliseconds of waiting for the next computation cycle plus the 5 milliseconds of processing within the computation cycle, totaling 15 milliseconds.

[0070] In the second-layer network structure, each communication module is designed with m links, which operate in parallel, and each link connects to x I / O modules. Communication between the communication module and these I / O modules can be implemented based on the RS485 protocol, and the RS485 communication baud rate can be set to support up to 5Mbps. To ensure efficient and accurate communication between the communication module and the I / O modules, the communication module uses a polling method to manage communication with the I / O modules, avoiding frame collisions and helping to ensure that each I / O module can communicate with the main control module in a timely and effective manner. This design of parallel links + polling improves data transmission bandwidth and parallel processing capabilities, enabling the system to handle more I / O requests simultaneously. When the communication module has a built-in ECC module, the polling method is specifically ECC polling, a data communication polling method that incorporates ECC technology.

[0071] Taking a nuclear power plant's DCS with 7680 switching points and 16 channels for each switching I / O module, the DCS requires a total of 480 switching I / O modules. Taking n=8 as an example, we can set m=6 and x=10 (8×6×10=480 switching I / O modules). Assuming that the communication time of each I / O module is strictly controlled to no more than 2 milliseconds, the acquisition response time of the last polled I / O module on the same link will not exceed 20 milliseconds (specifically, 2 milliseconds multiplied by the number of I / O modules on the link).

[0072] Referring to Figure 3, taking a nuclear power plant's DCS with 7680 switching points and 16 channels for each switching I / O module, the DCS requires a total of 480 switching I / O modules (n=8, m=6, x=10). Assuming the last communication module's acquisition response time is 8ms, the main control module's maximum calculation time is 15ms, and the last polled I / O module's acquisition response time is no greater than 20ms, then as shown in Figure 4, the loop control cycle consists of the following 7 parts:

[0073] T1: Processing time of the data acquisition I / O module;

[0074] T2: Transmission time between the communication module and the data acquisition I / O module;

[0075] T3: Transmission time between the main control module and the communication module;

[0076] T4: Main control module algorithm execution and processing cycle;

[0077] T5: Transmission time between the main control module and the communication module;

[0078] T6: Transmission time between the communication module and the output I / O module;

[0079] T7: Output class I / O module processing time.

[0080] The T1 time includes the A / D conversion time, hardware filtering time, and firmware runtime. The acquisition times for different types of signals are shown in Table 1.

[0081] Table 1 - Acquisition Schedule for Different Types of Signals

[0082] The longest T2 time is 20 milliseconds;

[0083] The longest T3 time is 8 milliseconds × 2 = 16 milliseconds, considering the redundancy of the dual communication modules;

[0084] The longest T4 time is 15 milliseconds;

[0085] T5 time is the same as T3 time, with a maximum of 16 milliseconds;

[0086] The T6 time is the same as the T2 time, with a maximum of 20 milliseconds;

[0087] T7 is the processing time for output I / O modules; it is 21 milliseconds for analog outputs and 6 milliseconds for digital outputs.

[0088] Therefore, the loop control cycle of the switching quantity is:

[0089] T = T1 + T2 + T3 + T4 + T5 + T6 + T7 = 0.5 + 20 + 16 + 15 + 16 + 20 + 6 = 93.5 milliseconds;

[0090] Similarly, referring to Figure 5, taking a nuclear power plant's DCS with 3840 analog points and 8 channels for the analog I / O modules, the DCS requires a total of 480 (3840 points / 8 channels = 480) analog I / O modules, with n = 8, m = 6, x = 10, a response time of 8ms for the last communication module, a maximum calculation time of 15ms for the main control module, and a response time of no more than 20ms for the last polled I / O module, the analog loop control cycle is:

[0091] T = T1 + T2 + T3 + T4 + T5 + T6 + T7 = 120 + 20 + 16 + 15 + 16 + 20 + 21 = 228 milliseconds;

[0092] As can be seen, compared with the traditional single-layer network structure of DCS, the embodiment of this application can support a larger scale of analog and digital signals (7680 digital signals + 3840 analog signals). In the case of large scale, the loop control cycle of analog signals does not exceed 300 milliseconds at most, and the loop control cycle of digital signals does not exceed 100 milliseconds at most. This ensures that DCS can still maintain an ideal loop control cycle when facing a large number of I / O modules and ensures the accuracy of automatic control.

[0093] When the number of links connected to each communication module is equal, and the number of I / O modules connected to each link is also equal, the DCS scale can be maximized under the same loop control cycle. Of course, depending on the actual design requirements, in any of the DCS disclosed above, the number of links connected to each communication module may not be exactly equal, and the number of I / O modules connected to each link may not be exactly equal.

[0094] In one possible implementation, any of the DCSs provided above is a DCS for nuclear power plants.

[0095] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other and will not be described again.

[0096] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of this application. Therefore, the embodiments of this application are not to be limited to the embodiments shown herein, but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A digital control system, characterized in that, include: The system consists of a main control module, n communication modules, and multiple I / O modules of the same type; n is an integer greater than 1. The main control module is connected to n communication modules via serial communication; the serial communication between the main control module and each communication module is implemented through their respective built-in field-programmable gate arrays (FPGAs), and the serial communication is based on gigabit serializer / deserializer (Serdes) technology. Each communication module is connected to multiple links that operate in parallel. Each link is connected to multiple I / O modules. Each communication module manages the communication with each I / O module connected to it using a polling method.

2. The digital control system according to claim 1, characterized in that, The Gigabit serializer / deserializer SerDes technology converts electrical signals into optical signals using a small, pluggable SFP module, and then uses optical fiber as the transmission medium.

3. The digital control system according to claim 1, characterized in that, The main control module and each communication module have built-in error checking and correction ECC modules.

4. The digital control system according to claim 3, characterized in that, The polling method is the ECC polling method.

5. The digital control system according to claim 1, characterized in that, The main control module combines a central processing unit (CPU) and an FPGA. Data acquisition tasks are run by the FPGA, while logic operation tasks are executed by the CPU.

6. The digital control system according to claim 1, characterized in that, Communication between the communication module and the I / O module is implemented based on the RS485 protocol.

7. The digital control system according to claim 1, characterized in that, The multiple I / O modules of the same type are n×m×x I / O modules of the same type. Each communication module is connected to m links that work in parallel. Each link is connected to x I / O modules, where m and x are both integers greater than 1.

8. The digital control system according to claim 7, characterized in that, The n×m×x identical I / O modules are n×m×x digital I / O modules, and the number of channels of the digital I / O modules is 16, n=8, m=6, x=10; Alternatively, the n×m×x I / O modules of the same type can be n×m×x analog I / O modules, with each analog I / O module having 8 channels, n=8, m=6, and x=10.

9. The digital control system according to claim 8, characterized in that, The maximum communication time for each communication module is no more than 1 millisecond. The processing cycle for logical operations by the main control module is set to 10 milliseconds. The communication time for each I / O module is limited to no more than 2 milliseconds.

10. The digital control system according to any one of claims 1 to 9, characterized in that, The digital control system is a digital control system used in nuclear power plants.

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