Industrial Data Communication

Unit 1: Local Area Network

A computer network is a collection of interconnected computers and devices that can communicate with each other to exchange data and resources. These networks can be as small as two devices connected in a local area network (LAN) or as large as a global network of computers connected via the internet.

Computer networks allow users to share resources, such as printers, files, and internet connectivity, as well as communicate and collaborate with each other using email, instant messaging, and other communication tools. They also enable remote access to resources and data, allowing users to work from different locations.

There are several types of computer networks, including local area networks (LANs), wide area networks (WANs), metropolitan area networks (MANs), and wireless networks, among others. These networks can be connected using various technologies, including wired Ethernet and wireless Wi-Fi.

1.1 Computer Networks in Automation

In today’s world, automation is a critical element in improving efficiency, reducing errors, and ensuring safety in various industries. Computer networks play an essential role in facilitating automation by enabling devices, machines, and control systems to communicate with each other and share information in real-time. The integration of computer networks allows for central control, monitoring, and the automation of industrial processes, providing greater control over operations and enabling remote access.

Need for Computer Networks in Automation:

1. Real-Time Communication: Networks enable real-time communication between devices and systems. For example, sensors can send data to controllers (e.g., PLCs) in real-time, which can then trigger actions such as turning on a pump, adjusting temperature, or stopping a machine. This ensures immediate responses to changing conditions.

2. Centralized Control: Through a network, different automated devices can be centrally monitored and controlled. Operators can adjust the operations of machinery, monitor production processes, and make real-time decisions from a central control room or even remotely, increasing productivity and minimizing downtime.

3. Data Collection & Analysis: Computer networks allow for efficient data collection from sensors, machines, and other devices. This data is crucial for process optimization, predictive maintenance, and identifying inefficiencies. With a network, collected data can be transmitted to a central database or cloud for analysis, leading to informed decision-making.

4. Remote Monitoring & Maintenance: With network connectivity, maintenance engineers can remotely monitor machine performance, diagnose faults, and perform software updates without needing to be physically present at the site. This reduces the need for frequent on-site visits and enhances operational efficiency.

5. Integration of Distributed Systems: In an industrial setting, automation systems are often spread out over large areas (e.g., production lines, warehouses, or even across multiple plants). Networks connect these distributed systems, ensuring that they work together as one cohesive unit, sharing data and resources in real-time.

6. Increased Safety: Networks help monitor safety conditions and automatically adjust systems when unsafe conditions are detected. For example, if a machine starts to overheat, the network can send a signal to shut it down or trigger cooling mechanisms, preventing damage or hazards.

Example of Network Application in Industrial Setup:

Example: Industrial Automation in a Manufacturing Plant (Assembly Line)

In a manufacturing plant (e.g., automobile or electronics assembly line), computer networks are used extensively to automate processes and increase production efficiency.

• Sensors and Actuators: Sensors on the assembly line continuously monitor conditions such as temperature, speed, pressure, and machine status. These sensors are connected to a central PLC or SCADA (Supervisory Control and Data Acquisition) system via a network. The PLC collects the sensor data and makes real-time decisions based on predefined thresholds.

• Real-time Monitoring and Control: For example, if a robot arm in the assembly line is programmed to perform a precise task, the network will provide feedback to ensure that the arm is operating within the desired parameters. If the robot arm deviates from the expected position, the network sends a signal to the PLC to adjust the arm's movement.

• Predictive Maintenance: Through the network, the system can monitor the health of machines. If sensors detect abnormal vibrations or temperature changes, the system can send alerts to maintenance personnel or trigger a scheduled shutdown before a failure occurs, thus preventing costly breakdowns.

• Centralized Monitoring: In large plants, operators can monitor and control multiple production lines or machines from a central control room. This networked system allows them to adjust production parameters remotely and in real-time without having to go to each individual machine, saving time and improving responsiveness.

1.2 Components of Computer System:

A computer system is made up of two main components: hardware and software.

Hardware refers to the physical components of a computer, such as the processor, memory, storage devices, and input/output devices. These are the tangible parts of a computer that you can touch and see.

The hardware components of a computer perform the basic physical operations required for a computer to operate. The main functions of the hardware components include:

1. Processing: The processor, also known as the central processing unit (CPU), performs mathematical and logical operations required for a computer to function.

2. Memory: Memory, also known as RAM, stores data and instructions temporarily for the processor to access.

3. Storage: Storage devices, such as hard drives and solid-state drives, store data and programs permanently for the computer to access even when it is turned off.

4. Input/Output: Input devices, such as keyboards and mice, allow users to input data and commands into the computer. Output devices, such as monitors and printers, allow the computer to display information and produce output.

Software, on the other hand, refers to the programs and operating systems that run on a computer. Software is intangible and exists only as a set of instructions executed by the hardware. It controls and manages the functions of the hardware, enabling the computer to perform various tasks, such as word processing, internet browsing, and gaming.

Together, the hardware and software components make up a complete computer system, with the hardware providing the physical capability to perform tasks and the software providing the instructions to control and manage those tasks.

The software components, on the other hand, provide the instructions and programs that control the hardware and perform specific tasks. The main functions of software components include:

1. Operating System: The operating system, such as Windows or macOS, is the foundation of a computer system and controls and manages the hardware and software components.

2. Applications: Applications, such as word processors, web browsers, and games, are programs designed to perform specific tasks and are run on top of the operating system.

3. Utility Programs: Utility programs, such as anti-virus software and backup programs, help maintain and optimize the performance of the computer system.

In summary, the hardware components provide the physical capability for a computer to perform operations, while the software components provide the instructions and programs to control and perform specific tasks.

1.3.Network topologies

Network topology refers to the layout and arrangement of devices on a computer network. It describes how devices are connected to each other and how data flows between them. There are several types of network topologies, including:

1. Star topology: In a star topology, all devices are connected to a central device, such as a switch or a hub. This central device acts as a central point of communication and controls the flow of data between devices.

Advantages:

• Easy to install and manage

• Easy to expand by adding new devices

• Provides central control and monitoring

• Reduces the impact of device failure

Disadvantages:

• • Requires more cable than other topologies

  • The central device is a single point of failure

  • May be more expensive than other topologies

2. Bus topology: In a bus topology, all devices are connected to a single cable, called the bus. Data flows along the bus and is received by all devices connected to it.

Advantages:

• Easy to install: Bus topology is one of the simplest and easiest topologies to install, since it requires only a single cable and connectors.

• Cost-effective: Bus topology is generally less expensive than other types of network topologies since it requires only a single cable and connectors.

• Easy to expand: Bus topology can be easily expanded by adding new devices to the bus.

• Reliable: The failure of a single device in a bus topology does not affect the rest of the network, as each device is independent and can communicate directly with other devices on the bus.

Disadvantages:

• Limited cable length: The length of the cable used in bus topology is limited, which makes it unsuitable for larger networks.

• Limited bandwidth: The available bandwidth in a bus topology is shared among all devices on the bus, which can result in slower network performance as more devices are added.

• Difficult to troubleshoot: If the network fails, it can be difficult to identify the location of the fault since all devices are connected to a single cable.

• Security: Bus topology is less secure than other types of network topologies since all devices have access to the same communication line. Unauthorized access to the bus can result in data breaches or other security issues.

3. Ring topology: In a ring topology, devices are connected in a circular manner, with data flowing from one device to the next in a circular direction.

Advantages:

• Efficiency: In a ring topology, data can be transmitted quickly and efficiently since there is no need for packets to be sent to a central hub or switch.

• Easy to install: A ring topology can be easily installed and configured. This is because the network devices are connected in a circular fashion, and there is no need for a central hub or switch.

• Reliability: Ring topology is known for its reliability as the data is transmitted in a unidirectional manner, which reduces the chances of collisions and data loss.

• Scalability: Ring topology can be easily expanded by adding new devices to the ring.

Disadvantages:

• Failure of a single device can bring down the entire network: Since each device in the network is connected to its nearest neighbors, the failure of a single device can bring down the entire network.

• Limited cable length: The cable length in a ring topology is limited. Therefore, it is not suitable for larger networks.

• Difficult to troubleshoot: In case of a failure in the network, it can be difficult to troubleshoot and locate the fault. This is because the network devices are connected in a circular fashion, and it can be difficult to determine where the fault lies.

• Cost: A ring topology can be more expensive than other types of network topologies since it requires a higher number of network devices.

4. Mesh topology: Mesh topology is a type of network topology in which every device is connected to every other device in the network, forming a mesh-like structure. Here are some advantages and disadvantages of mesh topology:

Advantages:

• Robustness: Mesh topology is highly robust, as there are multiple paths for data transmission. If one path fails, data can be rerouted through another path, ensuring the continuity of the network.

• Scalability: Mesh topology is highly scalable, as new devices can be easily added to the network without affecting the performance of the existing devices.

• High bandwidth: Mesh topology provides high bandwidth since every device is connected to every other device in the network.

• Security: Mesh topology provides a high level of security since data can be transmitted through multiple paths, making it difficult for unauthorized users to intercept the data.

Disadvantages:

• Cost: Mesh topology can be expensive to install and maintain since it requires a large number of cables and network devices.

• Complexity: Mesh topology is complex to implement and maintain, especially as the number of devices increases. The network must be carefully designed to ensure that every device is connected to every other device in the network.

• Redundancy: Mesh topology provides redundancy, but it can also result in data being transmitted multiple times, which can slow down the network.

• Difficult to troubleshoot: If the network fails, it can be difficult to identify the location of the fault since data can be transmitted through multiple paths.

The choice of network topology depends on several factors, including the size of the network, the type of applications being run, and the level of reliability and security required.

1.4.1 Network Classification Based on Transmission Technologies:

1. Point-to-Point: A point-to-point network consists of two nodes that are directly connected, and data can be transmitted in both directions. Examples of point-to-point networks include telephone lines and leased lines.

2. Broadcast: A broadcast network consists of a single communication channel that is shared by multiple nodes. The data transmitted by one node is received by all other nodes on the network. Examples of broadcast networks include radio and television broadcasting.

1.4.2 Network Classification Based on Scale:

1. LAN (Local Area Network): A LAN is a network that covers a small area, such as a home, office, or building. LANs are usually owned and operated by a single organization.

2. WAN (Wide Area Network): A WAN is a network that covers a large geographical area, such as a country or a continent. WANs are usually owned and operated by multiple organizations, and they use public or private communication links to connect different LANs.

3. MAN (Metropolitan Area Network): A MAN is a network that covers a city or a metropolitan area. MANs are usually owned and operated by a single organization, such as a government agency or a large corporation.

4. VPN (Virtual Private Network): A VPN is a network that uses public or private communication links to connect remote users or sites. VPNs are usually used to provide secure access to corporate networks from remote locations.

5. Internet: The Internet is a global network that connects millions of computers and networks around the world. The Internet uses standard communication protocols to transmit data between different networks.

Differences between LAN, WAN, and MAN:

1. LAN (Local Area Network):

• A LAN is a network that covers a small area, such as a single building or a campus.

• A LAN is usually owned and managed by a single organization, such as a company or a school.

• A LAN is typically connected using Ethernet cables or Wi-Fi.

• The data transfer rate on a LAN is typically very high, often up to 10 Gbps.

• Examples of LAN devices include desktop computers, laptops, printers, and servers.

2. WAN (Wide Area Network):

• A WAN is a network that covers a large geographical area, such as a country or a continent.

• A WAN is usually owned and managed by multiple organizations, such as service providers or governments.

• A WAN is typically connected using leased lines, satellites, or the internet.

• The data transfer rate on a WAN is typically slower than a LAN, ranging from a few Kbps to several Gbps.

• Examples of WAN devices include routers, switches, and modems.

3. MAN (Metropolitan Area Network):

• A MAN is a network that covers a metropolitan area, such as a city or a town.

• A MAN is usually owned and managed by a single organization, such as a local government or a public utility.

• A MAN is typically connected using fiber optic cables or wireless technologies.

• The data transfer rate on a MAN is typically higher than a WAN but lower than a LAN, ranging from a few Mbps to several Gbps.

• Examples of MAN devices include switches, routers, and bridges.

In summary, LANs are small-scale networks that are owned and managed by a single organization, WANs are large-scale networks that are owned and managed by multiple organizations, and MANs are medium-scale networks that are owned and managed by a single organization.

Configuration of LAN with example:

Configuring a Local Area Network (LAN) typically involves the following steps:

1. Determine the LAN topology: The first step in configuring a LAN is to determine the network topology. There are several types of LAN topologies, including bus, ring, and star. The most common topology used in modern LANs is the star topology, where all network devices are connected to a central device such as a switch or hub.

2. Choose networking equipment: Once you have determined the LAN topology, you need to choose the networking equipment that will be used. This may include switches, routers, hubs, network cards, and cables.

3. Configure the IP addresses: Every device on the network needs to have a unique IP address. This is typically done using the Dynamic Host Configuration Protocol (DHCP), which automatically assigns IP addresses to devices when they connect to the network. Alternatively, you can manually assign IP addresses to devices using a process called static IP addressing.

4. Configure network services: Once the network is up and running, you may need to configure various network services such as file sharing, printer sharing, and internet connectivity.

Example:

Suppose you want to configure a LAN for a small office with five computers. You decide to use a star topology with a switch as the central device.

1. Determine the LAN topology: You choose a star topology where all the computers will be connected to a central switch.

2. Choose networking equipment: You purchase a switch, five network cards for the computers, and Ethernet cables to connect everything.

3. Configure the IP addresses: You configure the switch to use DHCP to automatically assign IP addresses to the computers. Alternatively, you could manually assign IP addresses to each computer using static IP addressing.

4. Configure network services: You configure the file and printer sharing settings on each computer, and set up the switch to provide internet connectivity to all the computers on the network.

Once these steps are completed, the LAN should be up and running, and the computers should be able to communicate with each other and access the internet.

Wide Area Networks (WANs) offer several applications and services that enable communication and collaboration between geographically dispersed locations. Some of the common applications and services offered by WANs include:

1. Email and messaging: WANs enable users in different locations to send and receive email and messages through a variety of protocols such as SMTP, POP, and IMAP.

2. File sharing and storage: WANs allow users to share and access files stored on remote servers or cloud storage services. This facilitates collaboration between team members in different locations.

3. Video conferencing and webinars: WANs facilitate real-time audio and video communication between users in different locations. This is especially useful for virtual meetings, webinars, and remote training sessions.

4. Voice over IP (VoIP) and telephony: WANs enable users to make voice calls over the internet using VoIP technology. This can be used to make calls to other users on the same WAN or to external phone networks.

5. Remote access and virtual private networks (VPNs): WANs enable users to access corporate networks and resources from remote locations using VPNs. This allows remote workers to access internal systems and data as if they were in the office.

6. Cloud computing: WANs provide access to cloud computing resources such as software as a service (SaaS), platform as a service (PaaS), and infrastructure as a service (IaaS). This allows organizations to leverage cloud services to scale their IT resources and reduce costs.

Overall, WANs provide a wide range of applications and services that enable communication, collaboration, and access to resources across geographically dispersed locations.

1.4.3 Network Classification Based on Architecture:

1. Peer-to-Peer: A peer-to-peer network is a decentralized network where all nodes have equal status and can act as both clients and servers. In a peer-to-peer network, each node can share resources, such as files or printers, with other nodes.

2. Client-Server: A client-server network is a centralized network where one or more servers provide services to multiple clients. In a client-server network, the servers are responsible for managing resources, such as files or databases, and the clients are responsible for accessing those resources.

Advantages of Client-Server over Peer-to-Peer Model:

1. Scalability: Client-server networks can easily scale to accommodate a large number of users and resources. In a client-server network, the servers can be upgraded or replaced to handle increasing loads, while in a peer-to-peer network, the performance is limited by the capabilities of individual nodes.

2. Security: Client-server networks can provide better security than peer-to-peer networks. In a client-server network, the servers can be configured to enforce security policies and access controls, while in a peer-to-peer network, it is difficult to manage security across multiple nodes.

3. Centralized Management: Client-server networks provide centralized management of resources, which makes it easier to manage and maintain the network. In a peer-to-peer network, the resources are distributed across multiple nodes, which makes it difficult to manage and maintain the network.

4. Reliability: Client-server networks are more reliable than peer-to-peer networks because the servers can be configured to provide redundancy and backup. In a peer-to-peer network, the loss of a node can result in the loss of data or resources.

A Virtual Private Network (VPN) is a technology that enables users to securely access a private network over a public network such as the internet. A VPN works by creating an encrypted connection between the user's device and the VPN server, which then routes the user's internet traffic through the VPN server to the private network. Some of the key functions of VPNs include:

1. Secure remote access: VPNs provide secure remote access to internal networks and resources from any location, including public Wi-Fi networks. This enables remote workers to access internal systems and data as if they were in the office, while ensuring that their traffic is encrypted and protected from hackers and other threats.

2. Privacy and anonymity: VPNs provide privacy and anonymity by hiding the user's IP address and location. This makes it difficult for third parties to track the user's online activities or identify their physical location.

3. Bypassing geographic restrictions: VPNs can be used to bypass geographic restrictions and access content that is restricted in certain countries. For example, a user in a country where certain websites are blocked can use a VPN to connect to a server in a different country where the websites are accessible.

4. Enhanced security: VPNs provide enhanced security by encrypting the user's traffic and protecting it from interception and tampering by hackers or other malicious actors.

Example:

Suppose a remote worker needs to access the internal network of a company to work on a project. The internal network is only accessible from within the company's physical premises. The remote worker can use a VPN to securely access the internal network from any location, such as their home or a public Wi-Fi network. The VPN encrypts the user's traffic and routes it through the VPN server, which is located on the company's premises. This ensures that the user's traffic is protected from interception and tampering, while enabling the user to access internal resources as if they were in the office.