Lesson 66 Numerical Control
第 66 课 数控

 1

One of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control (NC).Prior to the advent of NC, all machine tools were manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.
先进制造技术领域最基本的概念之一是数控 （NC）。在 NC 出现之前，所有机床都是手动操作和控制的。在与手动控制机床相关的众多限制中，也许没有比操作员技能的限制更突出的了。通过手动控制，产品的质量直接关系到并仅限于操作员的技能。数控是摆脱机床人工控制的第一步。

Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions ^[1]. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions ^[2] to the machine tool.
数控是指通过使用预先录制的书面符号指令 ^[1] 来控制机床和其他制造系统。NC 技术人员编写一个程序，向机床发出操作指令 ^[2]，而不是操作机床。

 2

Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs ^[3] are lower. The development of NC led to the development of several other innovations in manufacturing technology:
数控技术是为了克服人工操作者的局限性而开发的，它已经做到了。数控机床比手动操作机床更精确，可以更均匀地生产零件，速度更快，并且长期模具成本更低^[3]。数控技术的发展导致了制造技术的其他几项创新的发展：

1. Electrical discharge machining.
1.电火花加工。

2. Laser cutting.
2. 激光切割。

3. Electron beam welding.
3.电子束焊接。

Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide variety of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tools and processes.
数控还使机床比其前身的手动操作更加通用。数控机床可以自动生产各种零件，每个零件都涉及各种多样且复杂的加工过程。数控技术使制造商能够使用手动控制的机床和工艺来生产从经济角度来看是不可行的产品。

Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U.S.Air Force.
与许多先进技术一样，NC 诞生于麻省理工学院的实验室。NC 的概念是在 1950 年代初期在美国空军提供的资助下开发的。

The APT (Automatically Programmed Tools) language was designed at the Servomechanism laboratory of MIT in 1956. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the further development of NC technology. The original NC systems were vastly different from those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper tape (see Fig.42.1), which was later to be replaced by magnetic plastic tape. A tape reader (see Fig.66.1) was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.
APT（自动编程工具）语言于 1956 年在麻省理工学院的伺服机构实验室设计。这是一种特殊的 NC 编程语言，它使用类似于英语的语句来定义零件几何形状、描述切削刀具配置并指定必要的运动。APT 语言的开发是 NC 技术进一步发展的重要一步。最初的 NC 系统与今天使用的 NC 系统大不相同。这些机器有硬接线的逻辑电路。教学程序写在穿孔纸带上（见图 42.1），后来被磁性塑料胶带取代。磁带阅读器（见图 66.1）用于解释机器磁带上写的说明。所有这些都代表了机床控制向前迈出的一大步。然而，NC 在其发展过程中存在许多问题。

Figure 66.1 A photo-electric paper tape reader 图 66.1 光电纸带阅读器

 3

A major problem was the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each successive time a part was produced on a machine tool, the paper tape carrying the programmed instructions had to be rerun through the reader. If it was necessary to produce 100 copies of a given part, it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.
一个主要问题是穿孔纸带介质的脆弱性。在加工过程中，包含编程指令的纸带断裂或撕裂是很常见的。这个问题因每次在机床上连续生产零件时，带有编程指令的纸带都必须通过阅读器重新运行这一事实而变得更加严重。如果需要制作给定部件的 100 份副本，则还需要将纸带穿过阅读器 100 次。易碎的纸胶带根本无法承受车间环境的严酷和这种重复使用。

This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than the paper tape, which solved the problem of frequent tearing and breakage. However, it still left two other problems.
这导致了一种特殊磁性塑料胶带的发展。纸带以胶带上打孔的一系列孔的形式承载编程指令，而塑料胶带则以一系列磁点的形式承载指令。塑料胶带比纸胶带坚固得多，解决了经常撕裂和破损的问题。然而，它仍然留下了另外两个问题。

The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it was necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problems of NC associated with punched paper and plastic tape.
其中最重要的是很难或不可能更改磁带上输入的说明。为了在指令程序中进行哪怕是最微小的调整，也必须中断加工操作并制作新的磁带。还需要将磁带通过阅读器的次数与要生产的零件一样多。幸运的是，计算机技术成为现实，并很快解决了与穿孔纸和塑料胶带相关的 NC 问题。

 4

The development of a concept known as direct numerical control (DNC) solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control, machine tools are tied, via a data transmission link, to a host computer^[4]. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend on a host computer. When the host computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.
一种称为直接数控 （DNC） 的概念的开发解决了与数控相关的纸张和塑料胶带问题，只需消除磁带作为承载编程指令的介质即可。在直接数控中，机床通过数据传输链路与主机相连^[4]。 用于操作机床的程序存储在主机中，并根据需要通过数据传输联动装置馈送到机床。直接数控代表了比穿孔带和塑料带向前迈出的一大步。但是，它与依赖于主机的所有技术一样受到相同的限制。当主机出现故障时，机床也会停机。这个问题导致了计算机数控的发展。

 5

The development of the microprocessor allowed for the development of programmable logic controllers (PLCs) ^[5] and microcomputers. These two technologies allowed for the development of computer numerical control (CNC).With CNC, each machine tool has a PLC (see Fig. 66.2) or a microcomputer that serves the same purpose. This allows programs to be input and stored at each individual machine tool. It also allows programs to be developed off-line^[6] and downloaded at the individual machine tool. CNC solved the problems associated with downtime of the host computer, but it introduced another problem known as data management. The same program might be loaded on ten different microcomputers with no communication among them. This problem is in the process of being solved by local area networks that connect microcomputers for better data management.
微处理器的发展允许开发可编程逻辑控制器 （PLC） ^[5] 和微型计算机。这两种技术促进了计算机数控 （CNC） 的发展。使用 CNC，每台机床都有一个 PLC（见图 66.2）或一台用于相同目的的微型计算机。这允许在每台单独的机床上输入和存储程序。它还允许离线开发程序^[6] 并在单个机床上下载。CNC 解决了与主机停机相关的问题，但它引入了另一个称为数据管理的问题。相同的程序可能加载到 10 个不同的微型计算机上，它们之间没有通信。连接微型计算机以实现更好的数据管理的局域网正在解决这个问题。

Figure 66.2 Programmable logic controllers 图 66.2 可编程逻辑控制器

Words and Expressions advent
单词和表达的出现

What is Direct Numerical Control?
什么是直接数控？

– 3 types of DNC Machine
– 3 种类型的 DNC 机器

Direct numerical control (DNC) is the process of controlling a machine tool or other device by sending it specific numerical commands to achieve the desired result.
直接数控 （DNC） 是通过向机床或其他设备发送特定的数字命令来控制机床或其他设备以达到所需结果的过程。

DNC systems typically send these commands from a computer located anywhere. This makes it possible to operate machines with unavailable on-site operators.
DNC 系统通常从位于任何地方的计算机发送这些命令。这使得可以在无法现场操作的情况下操作机器。

This blog post will explore the details of DNC systems and discuss some of their benefits. Stay tuned!
这篇博文将探讨 DNC 系统的细节并讨论它们的一些好处。敬请期待！

Table of Contents
目录

Definition
定义

DNC Machine
DNC 机器

Functions of Direct Numerical Control system
直接数控系统的功能

Advantages
优势

Types of direct numerical control
直接数控的类型

Direct Numerical Control software
Direct Numerical Control 软件

Uses of Direct Numerical Control software
Direct Numerical Control 软件的用途

Differences between Direct Numerical Control and Computer Numerical Control
直接数控和计算机数控的区别

Definition
定义

Direct numerical control (DNC) sends machine tool commands from a computer to a machine tool without requiring intermediate manual intervention. In addition, it enables unattended machining and provides process documentation.
直接数控 （DNC） 将机床命令从计算机发送到机床，而无需中间的人工干预。此外，它还支持无人值守加工并提供过程文档。

The set of machines mentioned above uses computer numerical control (CNC)
上述机器集使用 计算机数控 （CNC）.

Another name for it is Distributed Numerical Control.
它的另一个名称是分布式数控。

What is computer numerical control (CNC)?
什么是计算机数控 （CNC）？

Originally designed to automate manufacturing, CNC is a system that controls the destination and action of a machine tool. The software involved with this process is CAD/CAM or Computer-Aided Design/Computer-Aided Manufacture, which develops the needed commands for these tools depending on calculations from programs such as Pro E.
CNC 最初旨在实现自动化制造，是一种控制机床目的地和动作的系统。此过程涉及的软件是 CAD/CAM 或计算机辅助设计/计算机辅助制造，它根据 Pro E 等程序的计算为这些工具开发所需的命令。
For any machine to work, it has to be fed instructions on what materials need to be cut and where they need to go. Before, computers calculated these instructions manually or relied on time-consuming trial and error experiments. Still, they can generate computer code that gives accurate instructions every time without the worker wasting hours trying different combinations that may not even work.
任何机器要工作，都必须收到有关需要切割哪些材料以及它们需要去哪里的指令。以前，计算机手动计算这些指令或依赖于耗时的试错实验。尽管如此，他们仍然可以生成每次都能给出准确指令的计算机代码，而不会让工人浪费时间尝试甚至可能不起作用的不同组合。

It is based on real-time data and involves data collection from the machines and passing it to the mainframe. The operator will be in control of the mainframe computer through remote access.
它基于实时数据，涉及从机器收集数据并将其传递到主机。操作员将通过远程访问控制主机。

A DNC will not contain a tape reader. Instead, several part programs are transferred to the machines from the computer memory.
DNC 将不包含磁带读取器。相反，几个零件程序从计算机内存传输到机器上。

The machine controllers will not store the entire program in a few scenarios because of the lack of memory space.
由于内存空间不足，机器控制器在少数情况下不会存储整个程序。

If the program is stored on a different computer, the directions can be sent directly to the machines.
如果程序存储在不同的计算机上，则可以将路线直接发送到机器。

The DNC is designed to provide separate instructions to every machine. Thus, when the machine immediately controls the command, they are sent across directly.
DNC 旨在为每台机器提供单独的指令。因此，当机器立即控制命令时，它们会被直接发送。

DNC Machine
DNC 机器

What does a DNC machine contain?
DNC 机器包含什么？

DNC machines typically contain a mainframe computer used to store and retrieve information related to the manufacturing process. They also have a large memory capacity, allowing them to hold large amounts of data. In addition, they are connected to other machines and computers to share information and coordinate production. Finally, they contain machine tools used to create the final products. DNC machines play a vital role in modern manufacturing with their advanced capabilities.
DNC 机器通常包含一台大型计算机，用于存储和检索与制造过程相关的信息。它们还具有较大的内存容量，允许它们保存大量数据。此外，它们还连接到其他机器和计算机，以共享信息和协调生产。最后，它们包含用于制造最终产品的机床。DNC 机器凭借其先进的功能在现代制造业中发挥着至关重要的作用。

Usually, only large organizations use them because smaller organizations can’t afford them due to higher costs.
通常，只有大型组织使用它们，因为较小的组织由于成本较高而负担不起它们。

Functions of Direct Numerical Control system
直接数控系统的功能

The central computer stores and edits the programs for all machine tools connected to it.
中央计算机存储和编辑与其连接的所有机床的程序。

On a requirement basis, it gives the stored program to the connected machines.
根据需求，它将存储的程序提供给连接的机器。

Having a shared database, it combines CAD with CAM.
它拥有一个共享数据库，将 CAD 与 CAM 相结合。

It links the central computer and plant computers connected through the network even though they are very far away.
它连接通过网络连接的中央计算机和工厂计算机，即使它们相距甚远。

Advantages
优势

Direct numerical control avoids the usage of punched taps and the reader from the system.
直接数控避免了使用穿孔丝锥和系统中的阅读器。

It helps the business to understand production performance by getting several reports and valuable data from the machines.
它通过从机器获取多个报告和有价值的数据来帮助企业了解生产绩效。

It helps in building a centralized control for the machines.
它有助于为机器构建集中控制。

Useful for time management and increased productivity
有助于时间管理和提高生产力

Convenient storage of part programs in several computer files
将零件程序方便地存储在多个计算机文件中

It helps the company to make a higher-level decisions
它帮助公司做出更高层次的决策

It helps the business to increase its computational ability
它帮助企业提高其计算能力

It supports management information systems effectively
它有效地支持管理信息系统

Disadvantages
弊

It is costly, and it requires high automated areas
它成本高昂，并且需要高度自动化的区域

Because of its central control system, if the computer fails, then all the activities of machines would be stopped
由于其中央控制系统，如果计算机出现故障，那么机器的所有活动都将停止

Types of direct numerical control
直接数控的类型

It can be divided into three types,
可分为三种类型，

RS232 – based
基于 RS232

Operates with a switch box or multi-port cable connections to connect several machines. It is used on older lathes, milling machines, and some Bridgeport-style mills.
使用开关盒或多端口电缆连接来连接多台机器。它用于较旧的车床、铣床和一些 Bridgeport 风格的铣床。

Terminal-based
基于终端

A CNC terminal is created to connect several programs. The main advantage of this system is that it’s easy to modify programs. In addition, the terminal enables the machine tool to be tested for accuracy before use.
创建一个 CNC 终端来连接多个程序。该系统的主要优点是易于修改程序。此外，该终端还可以在使用前对机床进行精度测试。

Network-based
基于网络

Direct access to NC programs without installing terminals and is thus highly efficient. It uses TCP/IP Direct Control Protocol (DCP) to quickly transfer programs to the machine tool.
无需安装端子即可直接访问 NC 程序，因此效率很高。它使用 TCP/IP 直接控制协议 （DCP） 将程序快速传输到机床。

Direct Numerical Control software
Direct Numerical Control 软件

Following are DNC software vendors
以下是 DNC 软件供应商

NCnet
NCnet 网络

Skytrends
天际趋势

Antech microsystem private limited
Antech microsystem 私人有限公司

Next tech CNC private limited
Next tech CNC 私人有限公司

Niha solutions
Niha 解决方案

Technovision CNC
Technovision 数控系统

Uses of Direct Numerical Control software
Direct Numerical Control 软件的用途

DNC software allows you to operate the system smoothly. Following are a few uses of it,
DNC 软件可让您顺利操作系统。以下是它的一些用途，

Helps to control uploads and downloads remotely.
帮助远程控制上传和下载。

Allows you to know the current status of machines.
让您了解机器的当前状态。

It allows you to take the maximum utilization of CNC systems and helps to keep on the total usage of CNC running.
它使您可以最大限度地利用 CNC 系统，并有助于保持 CNC 的总使用量运行。

The software provides a Preset/Protocol editor that helps for quick adjustments.
该软件提供了一个预设/协议编辑器，有助于快速调整。

Provides industry-standard editor that helps to easy usage.
提供行业标准的编辑器，有助于轻松使用。

It helps to improve the productivity of the operator.
它有助于提高操作员的生产力。

Removes or reduces machine downtime for program transfer.
消除或减少程序传输的机器停机时间。

It avoids the mixing of programs.
它避免了程序的混合。

Increases productivity and efficiency by comparing the files automatically.
通过自动比较文件来提高生产力和效率。

Provides security by tracking and monitoring the changes to files.
通过跟踪和监控文件更改来提供安全性。

It provides easy access to graphical toolbars.
它提供对图形工具栏的轻松访问。

Differences between Direct Numerical Control and Computer Numerical Control
直接数控和计算机数控的区别

Conclusion
结论

The DNC is a technique that uses numerical input to control the movement of machine tools. This technique is used for metal fabrication or woodworking, but it’s most often used in CNC machining.
DNC 是一种使用数字输入来控制机床运动的技术。这种技术用于金属制造或木工，但最常用于 CNC 加工。

The Future of Direct Numerical Control
直接数控的未来

Its future of it looks promising. New developments in wireless technology and the internet are becoming more accessible and easier for various applications.
它的未来看起来很有希望。无线技术和互联网的新发展正变得越来越容易获得和更容易用于各种应用。

It will continue to be used in manufacturing, and we can expect to see more and more such machines in one form and advanced IoT(Internet of Things) technology as time goes on.
它将继续用于制造业，随着时间的推移，我们可以期待看到越来越多的此类机器以一种形式和先进的 IoT（物联网）技术出现。

What Is Direct Numerical Control And Their Types?
什么是直接数控及其类型？

September 25, 2021 by Jignesh Sabhadiya
九月 25， 2021 by Jignesh Sabhadiya

What Is Direct Numerical Control?
什么是直接数控？

Direct numerical control (DNC), also known as distributed numerical control (also DNC), is a common manufacturing term for networking CNC machine tools. On some CNC machine controllers, the available memory is too small to contain the machining program (for example machining complex surfaces), so in this case, the program is stored in a separate computer and sent directly to the machine, one block at a time.
直接数控 （DNC），也称为分布式数控（也称为 DNC），是数控机床联网 的常用制造术语。 在某些 CNC 机床 控制器上，可用内存太小，无法容纳加工程序（例如加工复杂表面），因此在这种情况下，程序存储在单独的计算机中，并直接发送到机床，一次一个块。

If the computer is connected to a number of machines, it can distribute programs to different machines as required. Usually, the manufacturer of the control provides suitable DNC software. However, if this provision is not possible, some software companies provide DNC applications that fulfill the purpose.
如果计算机连接到多台计算机，则它可以根据需要将程序分发到不同的计算机。通常，控制器的制造商会提供合适的 DNC 软件。但是，如果无法提供此规定，一些软件公司会提供满足此目的的 DNC 应用程序。

DNC networking or DNC communication is always required when CAM programs are to run on some CNC machine control.
当 CAM 程序要在某些 CNC 机床控制上运行时，始终需要 DNC 网络或 DNC 通信。

Wireless DNC is also used in place of hard-wired versions. Controls of this type are very widely used in industries with significant sheet metal fabrication, such as the automotive, appliance, and aerospace industries.
无线 DNC 也用于代替硬接线版本。这种类型的控制器非常广泛地用于具有大量钣金制造的行业，例如 汽车、家电和航空航天行业。

Understanding The DNC Machining
了解 DNC 加工

Direct Numerical Control (DNC) is a process set in a manufacturing unit where a set of machines is controlled by a programmed computer with the help of a direct connection to the same.
直接数控 （DNC） 是制造单元中的一个过程，其中一组机器由编程计算机控制，并借助直接连接到同一机器。

Set of machines mentioned above use computer numerical control (CNC). It is based on real-time data and involves data collection from the machines and passing the same to the mainframe, at regular intervals. The operator will be in control of the mainframe computer through remote access.
上述机器集使用计算机数控 （CNC）。它基于实时数据，涉及从机器收集数据并定期将其传递给主机。操作员将通过远程访问控制主机。

A DNC will not contain a tape reader. Instead, it has several part programs that are transferred to the machines from the computer memory.
DNC 将不包含磁带读取器。相反，它有几个部分程序从计算机内存传输到机器。

In a few scenarios, the machine controllers will not be able to store the entire program because of the lack of memory space. In such situations, the program is stored in a different computer and the directions are sent directly to the machines from that location.
在少数情况下，由于内存空间不足，机器控制器将无法存储整个程序。在这种情况下，程序存储在不同的计算机中，并且路线将从该位置直接发送到机器。

The DNC is designed in such a way that it provides separate instructions to every machine on the system. In case, where the machine immediately controls the command, they are sent across immediately.
DNC 的设计方式使其为系统上的每台计算机提供单独的指令。如果机器立即控制命令，它们会立即发送。

Functions Of Direct Numerical Control (DNC) System
直接数控 （DNC） 系统的功能

The central computer is used to store and edit the programs for all machine tools connected to it
中央计算机用于存储和编辑与其连接的所有机床的程序

On requirement, basis gives the stored program to the connected machines
根据需要，basis 将存储的程序提供给连接的机器

Having a common database, it combines CAD with CAM
拥有通用数据库，将 CAD 与 CAM 相结合

Provides a link between the central computer and plant computers connected through network even though plant computers are very far
在中央计算机和通过网络连接的工厂计算机之间提供链接，即使工厂计算机相距甚远

Types Of DNC System
DNC 系统的类型

Following are the main two types of DNC system:
以下是 DNC 系统的主要两种类型：

Behind the Tape Reader (BTR) system
磁带阅读器 （BTR） 系统背后

Specialized MCU
专用 MCU

1. Behind The Tape Reader (BTR) System
1. 磁带阅读器 （BTR） 系统背后

In this type of system, the computer is connected directly to the regular NC controller unit. The operation of the system is similar to conventional NC, except for the source of command instructions.
在这种类型的系统中，计算机直接连接到常规的 NC 控制器单元。该系统的操作类似于 传统的 NC，除了命令指令的来源。

The controller unit employs two temporary storage buffers to get the blocks of instructions from the DNC computer and turn them into machine operations. The one buffer is getting a block of data, the other is providing control instructions to the specific machine tool. This system cost is very low.
控制器单元使用两个临时存储缓冲区从 DNC 计算机获取指令块并将其转换为机器操作。一个缓冲区获取数据块，另一个缓冲区向特定机床提供控制指令。该系统成本非常低。

2. Specialized MCU
2. 专用 MCU

In a specialized MCU system, replace the normal controller unit with the special machine control unit. The special control unit is created to help communication between machine tools and computers. The specialized MCU configuration achieves a better balance between the accuracy of interpolation and the faster removal rate of the metal than is usually possible with the BTR system.
在专用 MCU 系统中，将普通控制器单元替换为专用机器控制单元。创建特殊控制单元是为了帮助机床和计算机之间的通信。与 BTR 系统通常相比，专用 MCU 配置在插值精度和更快的金属去除率之间实现了更好的平衡。

Advantages Of DNC
DNC 的优势

Direct numerical control avoids the usage of punched taps and the reader from the system.
直接数控避免了使用穿孔丝锥和系统中的阅读器。

It helps the business to understand production performance by getting several reports and useful data from the machines.
它通过从机器获取多个报告和有用数据来帮助企业了解生产性能。

It helps in building a centralized control for the machines.
它有助于为机器构建集中控制。

Useful for time management and increased productivity.
有助于时间管理和提高生产力。

Convenient storage of part programs in several computer files.
将零件程序方便地存储在多个计算机文件中。

Helps the company to make higher-level decision
帮助公司做出更高层次的决策

It helps the business to increase computational ability
它帮助企业提高计算能力

It supports management information system effectively
有效支撑管理信息系统

Disadvantages Of DNC
DNC 的缺点

DNC is very expensive and it requires high automated areas
DNC 非常昂贵，并且需要高度自动化的区域

Because of its central control system, if the computer fails then all the activities of machines would be stopped
由于其中央控制系统，如果计算机出现故障，则机器的所有活动都将停止

Differences Between Direct Numerical Control And Computer Numerical Control
直接数控和计算机数控的区别

DNC means direct numerical control; CNC means computer numerical control.
DNC 表示直接数控;CNC 表示计算机数控。

In CNC working operations cannot be controlled remotely. But in DNC we can control working operations with remote.
在 CNC 工作中  ，操作无法远程控制。但是在 DNC 中，我们可以通过远程控制工作操作。

CNC transfers machine instructions. DNC controls the information and manages the information distribution to more verities of computers.
CNC 传输机器说明。DNC 控制信息并管理向更多计算机的信息分发。

CNC machine controls only one NC machine, whereas by using a DNC programmer you can control more than one NC machine as per the requirements.
CNC 机床仅控制一台 NC 机床，而通过使用 DNC 编程器，您可以根据需要控制多台 NC 机床 。

DNC systems can be placed at a distance from machines. Because it not an integral part of machines. But CNC is an integral part of machines.
DNC 系统可以放置在离机器较远的地方。因为它不是机器的组成部分。但 CNC 是机器不可或缺的一部分。

CNC system has low processing power, DNC system has high processing power.
CNC 系统的处理能力低，DNC 系统的处理能力高。

DNC did not remove the tape, while CNC is a feedback system.
DNC 没有去除胶带，而 CNC 是一个反馈系统。

The maintenance cost of the DNC machine is low but the maintenance cost of the CNC system is high.
DNC 机器的维护成本低，但 CNC 系统的维护成本高。

CNC system amplifies the capacity of the particular computing machine tool. DNC system controls the equipment and also acts as a management information system.
CNC 系统 放大了特定计算机机床的能力。DNC 系统控制设备，同时也充当管理信息系统。

What Is Direct Numerical Control And Their Types? - Engineering Choice
什么是直接数控及其类型？- 工程之选