The Anybus Gateway System Information Technology Essay

Published: 2021-07-23 23:40:05
essay essay

Category: Information Technology

Type of paper: Essay

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

Hey! We can write a custom essay for you.

All possible types of assignments. Written by academics

GET MY ESSAY
Abstract
The following report contains the details of a multiple network protocol project carried out during the final year of a BEng Electrical engineering degree course. The report will give a detailed explanation of the project undertaken along with concise explanations of all work carried out. It will also show the vast research carried prior to the implementation of the network along with all problems encountered during the course of the project.
As told from the project brief, the aim of this project is to produce a functional data communications system. The objective is to have a minimum of three peripherals and a human/machine interface (HMI). The central hub will use the TCP/IP protocols which provide the capacity for future internet access as the project evolves. The peripherals will use industry standard protocols such as Modbus, CAN and DH+ etc.
This report will inform the reader on how a modern networking system operates, the boundaries to which a network must abide to along with the obstacles that will be encountered if one decides to replicate this project. This report will be sub-divided into a number of sections including but not confined to: research, implementation of various networking protocols, construction of networks, data transfer, software and hardware installation and configuration.
Each of the aforementioned stages will be as detailed as possible to give an overall understanding of the importance of networks in today’s modern world. It will provide an illustration of how computer networks and communication within networks are necessary and so widely used in modern industry.
Chapter One:
Introductory Chapter
Introduction
Communication networks exist in many different formats, they can be as simple as one person speaking directly to another or as complicated as astronauts relaying messages from the surface of the moon back to earth. Networking systems have existed for millions of years, smoke signals were used by the Native Americans to send messages for hundreds of miles, and Carrier pigeons were given the task of transferring notes from one town to the next in ancient Greece.
Today computer networking is at the forefront of modern industry. This report will showcase the necessity for a computer networking system in the day to day running of most large modern companies. Networking is vital for the fast and secure transfer of data and communications within a company internally.
The overall goal of this project was to research how to construct a network incorporating a number of different industry standard protocols along with design and construction of such a network. Chapter two will begin with introducing the vast amount of research which took place and summarise the most important results obtained. An overview of the general network types and their components will be shown. This chapter will include how the concept of networking was introduced and the evolution of the Ethernet from its humble beginnings to a truly vital component in today’s workplace. The limitations of a network and what governs modern protocols will also be discussed.
In chapter three of this report the methods used to design the network will be discussed in sequential order. There will be detailed and precise guidelines of every step taken from research to design to construction of the multiple protocol network. From these guidelines it is hoped that the reader will acquire the knowledge needed to reproduce a similar network for one’s self if desired.
Chapter four will discuss all results and findings obtained throughout the project module along with non-achieved targets if applicable. Results obtained with be compared and contrasted with similar systems already available in industry.
Chapter Two:
Literature Review
Literature Review
2.0 Intro
In this chapter the author will give a brief introduction into computer networking while also focusing on the necessity of networking in all aspects of modern life. However this report will mainly focus on networking in industry and will discuss the vital role it has to play. There will also be a brief insight into how computer networking evolved from its early beginnings right through to how it is applied today. In this chapter the use of the various types of networks along with the protocols they incorporate will also be discussed.
2.1 Computer Networking
A computer network is a collection of computers and other hardware devices interconnected by communication channels that allow for the sharing of both resources and information. Networking is the process of linking two or more computers together for the purpose of sharing data.
Networks incorporate a mix of both computer hardware and computer software.
Networks enable user to share files and resources such as printers, and also allow for the sending of electronic communications to one another such as email.
There are two main categories into which a computer network will fall:
Client/server networks
Peer-to-peer networks
These two types of networking models and how they work will be discussed in detail further into the report.
The most common networks are what are known as LAN’s (Local Area Networks). A LAN is usually used to connect devices within one geographical location such as an office building, a school or a residential building. Another common network types is what is known as WAN (Wide Area Network), a WAN differs from a LAN in the area it covers. A WAN may span throughout entire countries and even internationally using phone lines and satellites.
Networks may also be categorised in other ways to, sometimes a network may be referred to by the kind of circuit board the computers are using to link with one another.
Ethernet and Token-ring are two of the most common ways for computers to be linked. Networks are also sometimes referred to by how it packages data for transfer across the communication cable. TCP/IP (Transmission Control Protocol/Internet Protocol) is one of the most common methods and will be discussed in detail in this chapter.
2.1.1 Client/Server Network
A client server network is an operating system which allows the network to centralise functions and applications in one or more dedicated file server. The server is the heart of the network. It provides access to all of the networks resources along with providing security for the network. A client which is an individual workstation will have access to all the resources that are available on the servers. This network operating system integrates all the computers on the network and allows for multiple users to simultaneously share the same resources irrespective of physical location. UNIX/Linux Microsoft Windows servers are all example of network operating systems which use client/server.
Figure : Client/server networkinghttp://t0.gstatic.com/images?q=tbn:ANd9GcQSN9nAYEFOeIElZBktGxocH2WYR3ovPbLc6oB2kxYM_SqQV1uFNQ
Advantages of a client/server network are:
A client/server network is centralized so resource and data security is controlled through the server.
Client/server networks have scalability i.e. any or all of the elements on the network can be individually replaced as needs increase.
Client/server networks are flexible allowing for new technology to be easily integrated into the system.
Interoperability: all components (client, network and server) work together.
Accessibility: A server can remotely accessed and from across multiple platforms.
Disadvantages of a client/server network are:
Client/server networks require initial investment in a dedicated server which adds extra expense.
Large networks will require maintenance and possibly staff to ensure efficient operation.
If a server goes down all operation will cease throughout the network.
2.1.2 Peer-to-Peer Network:
A peer to peer network is an operating system which allows users to share files and other resources obtained on their computers as well allowing access to shared resources found on other computers. However a peer to peer network does not have a file server or centralised management source. All computers are considered equal in a peer to peer network; they all have the same ability to use the resources that are available on the network. A peer to peer network is primarily designed to be used within a small to medium LAN. Almost all modern desktop operating systems such as Windows, Macintosh, Linux and OSX can function as peer to peer network operating systems.
Advantages of a peer to peer network are:
There is less initial expense as there is no need to provide a dedicated server.
An operating system already in place such as Windows XP may only need to be reconfigured to operate on a peer to peer network.
Disadvantages of a peer to peer network are:
Peer to peer networks are decentralized: there is no central origin for files and applications.
Security is less than that which is provided on a client/server network.
Figure : Peer-to-peer networking
2.2 Network Protocols:
A definition of a Protocol is: ‘A network Protocol defines rules and convention for communication between network devices’ (Mitchell 2013).
A network protocol is a formal set of rules, conventions and data structures that govern how computers and other network devices exchange information over a network. Protocols are standard procedures which devices must understand, accept and use in order to talk to one another.
In modern Protocol design, network protocols are ‘layered’ according to the OCI model. Layering is a design protocol which divides the protocol into a number of smaller parts. Each layer has the function of completing a particular sub-task. Layering allows the parts of a protocol to be designed and tested without an explosion of cases, keeping each design relatively simple. Layering also permits familiar protocols to be adapted to unusual circumstances.
There are many network protocols which are in existence; one of the most common network protocol suites is TCP/IP. This protocol is the heart of internetworking communications. The internet protocol is what governs the exchanging of information between routers; this allows routers to select the proper path for the network traffic. The TCP ensures the data packets are transmitted across the network reliably and error free. LAN and WAN protocols are also critical in network communications. The LAN protocol suite is for the physical link and data link layer communications over various LAN media such as Ethernet wires and wireless waves. The WAN protocol suite governs the lowest three layers and it is used to define communications over wide area media such as fibre optic and cables.
Protocols can be incorporated into hardware or software, or a mixture of both. Normally it is seen that the lower layers are used with hardware whereas the higher layers are implanted with software.
2.2.1 The OSI Model:
Virtually all networks which are in use today are centred on the Open Systems Interconnection (OSI) standard. The OSI was developed in 1984 by the International Organisation for Standardisation (ISO) which is global federation of national standards organisations which represent over 130 countries.
At the core of this standard is the OSI reference model, which is a set of seven layers which govern the different stages which data must go through while travelling from one device to another over a network
Layer 7: application layer - this layer is the layer which actually interacts with the operating system when a user decides to transfer a file, read a message or preform any other network related activity.
Layer 6: presentation layer – this layer takes the data which is provided by the application layer and then converts it to a standard format that other layers can understand and use.
Layer 5: session layer – the purpose of layer 5 is to establish, maintain and cease communication with receiving device
Layer 4: transport layer – this layer maintains flow control of data and recovery of data between devices. The basics of flow control is that the transport layer checks to see if data is being sent from numerous applications, if so it will integrate each applications data into one single stream for the physical network.
Layer 3: network layer – how data will be sent to a recipient device will be determined by the network layer, logical protocols, routing and addressing are handled by the network layer.
Layer 2: data layer – in the data layer the required physical protocol is assigned to the data, also the packet sequencing and the type of network is defined by this layer.
Layer 1: physical layer – this is the actual hardware being used by the user, it will define the physical characteristics of the network, such as voltage levels and timing.
OSI Reference Model is merely used as a guideline but in real life situations a number of layers are sometimes combined into more than one.
Figure : OSI Modelhttp://www.petri.co.il/images/osi_model.JPG
OSI model researched at: www.computer.howstuffworks.com
2.2.2 Ethernet:
Nowadays the Ethernet is taken for granted, we simply plug a cable into the socket on the wall and we are connected to the network – problem solved. In the 60’s and 70’s it was a completely different story, networks were ad hoc had little rhythm and less reason.
Ethernet became a reality when Bob Metcalfe was presented with the task of constructing a local area network (LAN) for the Xerox Corporation in their Palo Alto Research Centre (PARC). Metcalfe’s creation the Ethernet changed everything.
It was in 1972 when Bob Metcalfe, David Boggs other members of the PARC team were given the challenge of connecting PARC’s Xerox Altos computer (the first personal workstations with a graphical user interface) with the world’s first laser printer the Scanned Laser Output Terminal.
It wasn’t a trivial problem to overcome. The network needed to have the ability to connect hundreds of computers simultaneously and it also needed to be fast enough to drive a laser printer. Metcalfe looked at previous works to find inspiration and in particular he looked to Norman Abramson’s paper about the ALOHA net packet radio system. The ALOHA net was used for packet communications throughout the Hawaiian Islands. The ALOHA net differed from the ARPAnet by using shared medium UHF frequencies instead of dedicated connections. Metcalfe was particularly impressed with ALOHAnet because it addressed one major issue: how the technology coped when there was a collision between packets. These collisions occur when there are two radios broadcasting simultaneously. With ALOHAnet the nodes would rebroadcast these ‘’lost in ether’’ packets after waiting a random interval of time. While this was a primitive version of collision avoidance it did work relatively well, although Metcalfe noticed from Abramson’s paper that ALOHAnet would reach it maximum traffic load when only 17% of its potential maximum efficiency was reached.
Metcalfe had previously worked on this problem while in graduate school, and he had discovered with the right packet queuing algorithms he could reach 90% efficiency of the potential traffic capacity. This work he had done was to become the basis of the Ethernet’s media access control (MAC) rules: Carrier Sense Multiple Access with Collision Detect (CSMA/CD).
In the case of PARC a wireless solution was not practical so Metcalfe opted to use a coaxial cable. Metcalfe and his team at PARC decided against calling it the COAXnet which had been suggested, instead Metcalfe borrowed a phrase from 19th century scientific history ‘Ether’. Back then ‘Luminous Ether’ was the phrase used to describe the medium through which light travelled.
"The whole concept of an omnipresent, completely passive-medium for the propagation of magnetic waves didn’t exist. It was fictional. But when David [Boggs] and I were building this thing at PARC, we planned to run a cable up and down every corridor to actually create an omnipresent, completely-passive medium for the propagation of electromagnetic waves, In this case, data packets." - Bob Metcalfe (S. Vaughan Nichols, 2012)
On May 22nd 1973 Metcalfe gave a presentation to the Xerox Corporation explaining how his proposed Ethernet would work. And with their approval he began installing a coaxial cable throughout the corridors of the PARC building. On November 11th 1973 the first computers were connected to this bus-style network.
Within PARC’s hallways Ethernet with a speed of 3Mbps (megabits per second) became an immediate success. Bob Metcalfe’s original drawing for the Ethernet can be seen below in Fig 4:
Figure : Bob Metcalfe's original Ethernet Drawingethernet.gif
Over the next number of years the Ethernet was remained a private in-house system used only at PARC. But in 1976 Metcalfe and Boggs published a paper which they titled: "Ethernet: Distributed Packet-Switching for Local Computer Networks". Although the Xerox Corporation had originally patented the technology they were open to allowing others the use of it.
In 1979 Metcalfe left Xerox to form his own company called ‘3Com’. By that time he had convinced Xerox, DEC and Intel to agree with commercialising the Ethernet. Due to internal conflicts within the consortium and various hurdles to overcome it wasn’t until June 23rd 1983 that the Ethernet was approved as a standard.
By now Ethernet had reached speeds of up to 10Mbps and was well on the road to becoming globally popular. Although popular the Ethernet in its infancy wasn’t exactly easy to attach a device to. The original Ethernet used a 9.5mm coaxial cable also known as a ‘Thicknet’ or also affectionately known as ‘frozen yellow snake’ for it notoriously stiff characteristics. To attach a device to this a small hole needed to be drilled into the cable itself to place a ‘vampire tap’ which was also notoriously difficult to attach. The kit which was required for this demanding job can be seen below in Fig 5:
Figure : Thicknet kit10Base5transcievers.jpg
10Base2 also known as ‘Thinnet’ was soon to follow and was far easier to connect to than the original because it used a small coaxial similar to the cable you use to connect your television to the provider. This made laying out a network a far easier task not to mention a lot less physical. In addition the use of a simple t style connector made it easier to connect to eliminating the drilling and vampire tap. But 10Base2 had one major disadvantage accompanying it; if the cable was severed or damaged somewhere along the route the entire network segment collapsed. For example in a large scale office with dozens of computers on a network tracking down the broken connection could be a major time consuming issue.
By the 1980’s, shield twisted pair (UTP) was beginning to replace 10Base5 and 10Base2, and this technology known as 10BaseT and its many descendants such as 100Base-TX and 1000Base-T are what we still use today.
Ethernet and its system of cabling was not without its challengers and in the 1980’s it faced stiff competition from two other networking technologies:
Token Bus which was being promoted by GM for networking in factories and IBM’s far more popular Token Ring had arrived on the networking scene. Token Ring had far greater bandwidth efficiency. Token ring had a Packet size of 4550bytes at 4Mbps compared to Ethernets 1514bytes at 10Mbps, which made Token Ring effectively faster than Ethernet. Even to a person not up to date with computer and network technology at the time it was clear to see 4550bytes was faster than 1514 bytes.
Another challenger to the Ethernet was ARCnet (attached resource computer network) which was created by Datapoint Corporation in the 1970’s and released in the 1980’s. Arcnet was also a token based protocol, and used a bus instead of a ring design. At the time its simple bus design and speed of 2.5Mbps made it an attractive alternative.
Numerous reasons ensured that Ethernet would win, notably the Digital Equipment Corporation (DEC) had decided early on that it would give Ethernet its support, which in turn gave the fledgling networking technology significant support in IEEE Standardisation process.
Ethernet was also comparably a far more open standard; IBM’s Token Ring was in theory open standard whereas in reality the vast majority of the time non IBM Token Ring equipment would not work with IBM computers. Ethernet was soon supported by over 20 large multi-national companies and was growing in stature, eclipsing its competitors. Mainly because Ethernet was open and with the large number of developers it had working with together it didn’t take long to close the technology gap between itself and Token Ring.
10BaseT which became a standard in 1990 allowed for the use of switch’s and hubs, this freed the Ethernet from its slow and awkward bus design to the flexibility of star architecture. This change not only allowed network administrators to manage their networks far easier, but also gave the user far greater flexibility when it came to deciding where to place their PC devices. Another deciding factor not to be overlooked was that in the early 90’s 10BaseT Ethernet was far cheaper than Token Ring. The final nail in the coffin came soon after when Ethernet switching and 100Mbps Ethernet became widely available.
In today’s modern world there may still be some Token Ring networks in use but more so for historical curiosity reasons than any other. Although Wi-Fi technologies are now immensely popular the Ethernet is still vital for supplying those Wi-Fi access points with network connectivity, and not to mention business that do not want their secrets continuously broadcast to the world.
2.2.3 Token Ring:
In token ring all the computers with in the network are arranged schematically in a circle. A special bit pattern which is known as a ‘token’ travels around the circle in one direction be it either clockwise or anti-clockwise. If a computer wants to send a message it will take the token, the computer will attach its message to the token and the token will continue to travel throughout the circle until it ends up back where it began. With token ring a token passing protocol is utilised. This means that a device may only use the network once it has control of the token. This will ensure that there will be no collisions due the fact that only one device can communicate at any given time. Ring topologies are often found in office buildings, schools, and college campuses etc.
Figure : Ring Topology layout
2.2.4 TCP/IP:
The development of TCP/IP was like an expedition to the summit of Everest. There were no human resistance, but the obstacles were formidable and potentially deadly, at least to one’s career. (TCP/IP Frank Derfler& Steve Rigney)
Transmission control protocol (TCP) and the internet protocol (IP) are two specific examples of network protocols. But what is a protocol? TCP and IP are two protocols which describe, in a very detailed fashion, the steps that two or more devices follow to move a packet of data from one computer to another across a connection medium. A protocol is basically an agreement set out as to how things will happen. For example there are international political protocols, communication protocols, medical protocols to name but a few. Sometimes a protocol can be developed or adopted by standards bodies. A good example of this would be the V.34 which was developed by the Telecommunications Industry Association (TIA) and went on to become an in TCP/IP is a network protocol system-a collection of protocols that support network communications. To understand what a network protocol is we firstly need to understand how a network works. A network can be defined as a collection of computers or similar devices that can communicate with one another across a common transmission medium.
2.3 Current systems reviewed
2.3.0 Intro
There are a number of systems currently available in industry which provides means of connection between different protocols. In the following chapter the author will review and discuss a number of these systems. The aim of this review is to provide a general overview of each system and how they may compare or contrast with the one aiming to be produced in this report.
2.3.1 The Anybus Gateway system
The Anybus X-gateway is a product which is developed and produced by HMS Industrial Networks. It is one of a number of products currently being produced by the manufacturer with the aim of providing connection between any two industrial protocols. This particular product supports seventeen different fieldbus networks which include: Profibus, CAN, Modbus, Ethernet-IP to name but a few. These ranges of products are designed for use in industrial automation plants primarily where numerous different networks are regularly incorporated. The x-gateway systems allow for easy interconnection between any two networks. This allows for a consistent information flow throughout an entire production facility or similar installation. The X-gateway system has been tested and is proven to be compatible with all the leading PLC manufacturers’ equipment; this includes Siemens, Mitsubishi, ABB, Omron, Hitachi, Allen Bradley and many more.
The X-gateway contains a built in configuration interface and so does not require programming which can be a key consideration when deciding on a product to choose. This system provides a predefined I/O size of 20bytes I/O, along with a built in configuration interface. There are also versions which contain a master interface but these types will also require the usage of an appropriate master configuration tool.
The X-gateway main focus is to provide transfer of cyclic I/O data between two separate networks. The system typically provides data transfer between two networks in 10-15milli-seconds. The system allows for connection with PC based OPC-Client applications via the standard Ethernet networks and the X-gateway to all major fieldbus networks. The X-gateway incorporates standard DIN-rail mounting and its design allows for its use in harsh industrial environments. It incorporates an IP rating of IP20 and requires a 30volt DC power supply. They are also certified for use in hazardous locations (HMS Industrial Networks).
Figure Anybus X-gateway
2.3.2 Compass
The technology to integrate building systems is already available to purchase from a number of manufacturers. One such system is the ‘Compass’ which is produced by North technologies. Compass is a relatively inexpensive, easily engineered and there are over 10,000 units already in operation worldwide. The compass system is also supported by many leading manufacturers, OEM’s and system integrators. Compass can be used to link almost any building automation system form air-conditioning to fire detection to power and lighting. Controls from many different manufacturers can also be combined to give previously unused and obsolete systems a new lease of life. Compass can also be used to control and monitor discrete systems such as lighting control, access and security etc. The compass system is also compatible with leading network standards such as Modbus, EIB nad BacNet.
Compass was the first network developed to specifically to provide data transport between building management systems. The system can also be used to support the latest displays and telecommunications. It can handle the range of data types along with the volume of communications found in modern buildings. Building controls and also monitoring data can vary enormously; it can range from simple values such as a fire detector status or the position of a camera or large text alarm messages. The compass system provides multiple messages handling which enables all messages on the compass network irrespective of size or type, to be treated with equal priority.
Connections onto intelligent systems are not normally found next to one another. More often than not the fire alarm panel may be found in the reception area, while the controls for the H&V system could be in the maintenance room, where as the controls for the security system could be in a security room. A single compass point may be used to inter connect each intelligent system from linking all compass points together. Distances of up to one kilometre between points are possible. Compass systems have the ability to link systems across numerous facilities; they can be used to bring total integration across even the largest facilities. Modems can be used to extend the scope of the application to estate management, remote monitoring, and data collection schemes. Compass provides a complete integration system and management platform which can improve building performance, site supervision and building maintenance.
The compass system is straight forward to fit with proven installation methods and automated engineering via the ObSys software provided. With the system there are also low connection costs, the industry standard device connections include RS232, RS422 and RS485. The system supports a large range of display methodologies including integrated supervisors and audio visual interfaces (Northbt.com).
2.3.3 Integrator
The integrator is a powerful multi-protocol controller which is developed by North technologies. The integrator system provides a configurable link between Ethernet networks.
The Integrator system also contains NorthBT’s Observer software as previously seen in the Compass system. This software provides the engineers with ability to write cause and effect strategy, calendar and timer functions along with the ability to provide data logging and single user interface for multiple systems in one single box. Integrator systems provide the user with two Ethernet ports along with two RS232 ports which provide a very good connectivity source. The integrator system via its interface technology can collect data directly from hundreds of third party products for all leading manufactures, such as; Sanyo, ABB, Gent, Siemens, Honeywell, Modbus and many more. Integrator connects directly to NorthBT’s distributed Zip I/O network and is an XOM compatible device allowing for connection to the Obys software.
Integrator is provided with a complete cause and effect processor (OBVProcess), which is capable of operating large complex strategies which can include systems such as HVAC controlling and intelligent systems. Each strategy is written using ObVerse in a graphical drag and drop editor. This software can directly reference values from any system which is attached to the system. This allows for full control of the system from one central point. For example, it can used to obtain the occupancy status of a room in a building by means of the intruder alarm system. This information can then be used to control lighting and fan points by directly referencing remote points in the ObServer strategy.
The Integrator system fully supports the eXtensible Object Model (XOM) protocol and are fully interoperable. The system can be web enabled using the Webview graphical interface provided. Web pages can be included in data logging, alarm event handling, mimic pages etc. This content is available to very broad range of web clients from desktop based internet explorer, Firefox, Safari to embedded browsers used in PDA’s, mobile phones etc.
The system is fully secure and offers a 960 point data base allowing for data collection from connected devices to be logged and transferred to other connected systems which can be then viewed on a Zip display module.
The Integrator system is also provided with the capability of remote engineering. This allows for the system to be fully configured and backed up remotely. The Integrators configuration and can be uploaded remotely while an engineer may also download all settings to their own PC or laptop creating a full simulation of The integrator on their own machine thus allowing for testing and off-line engineering.
The Web-view editor allow engineers to remotely manage files on a web view server and in turn create new pages, assign points and graphic in a simple easy usable environment. The programme also provides a vast library of ready to use graphics such as smoke-heads, PIR’s, valves, and pumps along with HVAC objects and many more. These pages can be remotely engineered over an internet connection.
The system provides a strong alarm handling capabilities which include modules which provide notification e-mails, SMS notification and notification to pager devices etc. Calendars and timers are controlled via an easy to use web interface which provides for control of up to twenty separate timers. The calendar function allows for easy setting of exception days, years in advance.
Integrator is provided as standard and contains all the key features described above along with many more. There is also a huge interface available and expansion modules which are available to ‘plug in’ on demand. A module could be used to enable a Modbus device and maybe to link a third party proprietary protocol or simple to provide some additional alarm handling or data logging features (NorthBT).
Chapter Three:
Methodology
Methodology
3.0 Intro:
Following on from the research stage it was now time for a physical build to begin. It had been determined from this research that a medium would be required to communicate between devices. The cables which would be used as the medium to connect the various computers in the network were to be constructed manually. It was decided that each member of the project team would need two crossover cables along with two patch cables. The equipment needed for the construction of these was acquired from the electrical workshop in the college although they are easily obtainable from electrical wholesalers if required.
3.1 Ethernet Cables:
Unshielded twisted pair cables (UTP) consists of eight insulated copper cables which are grouped together to form four separate pairs with a protective shield. UTP cable is specifically formed in this manner to reduce signal degradation and losses due to interference from various external sources.
The number of twists per pair can also be varied to reduce crosstalk noise. CAT5e (Category 5 enhanced UTP) is a cable commonly used as an Ethernet medium and was chosen because it can support data rated of 100Mbps and higher. It also has a maximum segment rate of up to 100metres which would easily accommodate this particular build. It was also chosen because it is readily available and easily accessible if further amounts are required. For termination of the devices an RJ-45 connector was used because it is the industry standard and supports the 10Base T and 100Base T used in modern Ethernet. Each cable of 10metre length needed to be fitted with an RJ-45 connector at each end. The Cat5e cable and RJ-45 connector can be seen below in Fig 8 & 9.
Figure : Cat5e cablehttp://image.made-in-china.com/2f0j00EsjQhIzJOaqU/Network-Cable-UTP-Cat5e.jpg
Figure : RJ-45http://3.bp.blogspot.com/-QSsZ_fxZC68/TuV2FXDjXzI/AAAAAAAADIs/U9ugkLbuIiE/s1600/rj45+connector.jpg
For the construction of each cable required a definitive termination code was obtained and needed to be followed precisely to prevent cross termination of cable cores. The terminating of the patch panel cable is relatively simple as both ends of the cable are terminated in exactly the same sequence as can be seen from FIG 10 below.
Figure : Patch cable colour codinghttp://t1.gstatic.com/images?q=tbn:ANd9GcTeKM6N790qBcfFUyIElP0G_U0UhSNO0051xTmLPRGOOUhXQLolVQ
Construction of the crossover cables is very similar to the steps taken in terminating the patch cables except for a slight difference in the terminating sequence. A diagram of the termination order is seen below in Fig 010 and should be followed directly to prevent wrongful termination.
Figure : crossover cable colour codinghttp://www.joncamfield.com/oss/schooltools/Reference/EthernetCabling_files/ethcablerj45cr.gif
As can be seen above both RJ-45 connectors are terminated differently although positioned at either end of the same length of cable. Following termination of each the cables were then tested for correct polarity and quality of termination to prevent any false reading at a later stage. A Chauvinarox structured cabling tester was used which again was obtained from the electrical workshop and is shown below in Fig 12.
Figure : Chauvinox testerC:\Users\Alan.sarah-HP\Desktop\Project Niall Murphy\Project photo's\week 2-3 photos\photo 7.JPG
Fig 011: Chauvinarox Tester
3.2 Peer-to-peer networking:
Using the cables constructed to provide a medium between devices, the construction of the very first network would now begin. The first type of network to be designed was a ‘peer-to-peer’ network. A brief description of a peer-to-peer network is as follows: "A network of personal computers, each of which acts as both client and server, so that each can exchange files and email directly with every other computer on the network. Each computer can access any of the others, although access can be restricted to those files that a computer's user chooses to make available. Peer-to-peer networks are less expensive than client/server networks but less efficient when large amounts of data need to be exchanged" (Houghton Mifflin 2005).
Figure : Peer-to-peer network layouthttp://t1.gstatic.com/images?q=tbn:ANd9GcTUWMiKxIXlPyB8DqeSH_HQ8hFFQjBZvhzgpiiWtMNWj3BvJgSc
Following the layout above in Fig 13 a small peer-to-peer network was constructed using two laptops each of which were interconnected using one of the crossover cables previously discussed. Peer-to-peer networking does not require the need for an individual server and each computer can be used to work both as a server and a client. Large amounts of data can be transferred at relatively fast speeds with this particular set-up. Each computer in this set up will need a compatible programme in order to transfer data.
Initially a new account user was set up individually on each computer to provide a common group; in this case the user on each computer was simply called ‘Project’.
The firewalls on each computer will also need to be disabled and this can be done by following these steps:
Control panel >> Security and devices >> windows firewall >> advanced settings >> windows firewall properties >> disable individual firewalls.
Connect both computer to one another by inserting either end of the same crossover cable in the RJ-45 ports available on the side each device.
Control Panel >> Network and Internet >> network sharing centre.
Following the above steps will show all computers that are now connected across the network and are accessible to each device. This network which has now been created is a Local Area Network (LAN). The wireless function on the computer should also be turned off to prevent any internet access which isn’t advisable when the firewalls are not active. To show the sharing capabilities of the LAN a Microsoft word document was created on computer A it was made accessible to all computers on the network. The document was then opened over the LAN and could be viewed from computer B; this showed that the file transfer had been successful.
We have now successfully transferred data between two computers the next stage is to extend the number of devices within the network. For this a router will be required to provide the number of ports required for connecting devices.
3.3 Client/Server networking:
Client/server describes the relationship between two computer programmes; the client makes a service request to another programme i.e. the server which then fulfils the request. This relationship is possible with one single computer but is far more important with regards to a network. The client/server model is one of the most important ideas in computer networking today. Most business applications today use the client/server model, including the internet’s min programme TCP/IP.
A router is a device which is used to transfer data packets from one point to another over a network. Having acquired the router a client/server network follows basically the same design principles as the peer-to-peer network. The aim here is to transfer data between three or more devices. The router provided was model/make: TP Link TL-WR841N which is seen below in Fig 14.
Figure : TP Link TL-WR841N Routerhttp://t0.gstatic.com/images?q=tbn:ANd9GcQ9zcwVjOdCBnQ9DVi8e4Mcuh4Gi664B0toDG1BY74oYF8J8uOkXw
A number of settings needed to be adjusted on the router to perform the tasks required in this particular scenario. The wireless function needs to be turned off to allow our data to be transferred over the LAN. The router has its own designated IP address (internet protocol) address which needed to be obtained. From searching the connectivity panel of the device its IP address was found to be 192.168.1.100. Each of the computers on the LAN has their own dynamic IP address. This is an IP address which changes every time the computer is disconnected and reconnected to the network, they are assigned to a computer automatically using DHCP (Dynamic host configuration protocol). For this particular project each device required a static IP address and this needs to be changed manually. A static IP address is one that will not change when the device is disconnected. It will be assigned the same IP address when reconnected to the LAN.
Figure : Client/server configuration
As seen from Fig 15 above, the setup of a client/server network is slightly different to a peer-to-peer network. A patch cable is taken from each individual device on the network and connected to the central router. The router is then indirectly linking each computer to one another by means of a central hub. Each computer was then assigned its static IP address; this is done by following the steps below:
Control panel >> Network and Internet >> Network & sharing centre >> set up a new connection or network.
To view each device now connected to the network, go to:
Control Panel >> Network and internet >> Network and sharing centre >> See full network map.
‘Pinging’ each computer will also verify that all devices are connected with one another. By pinging between each device it will confirm if any devices are unable to communicate with one another for whatever reason. To achieve this follow the following steps:
Control Panel >> Accessories >> Command Prompt
The following screen will pop up after following the above steps;
Figure : Command prompt window
With this pop up window available, type ‘Ping’ followed by the IP address of the device you wish to communicate with and press the Enter key on the computer. The computer will then send four packets of 32bit to the desired address. It will wait to receive a reply from the destination device. When the packets are received, the command prompt window will give feedback of how many packets were received and how long it took to receive them.
If a reply is not returned it will time out and the sent packets are lost.
In the images below Fig 17 & Fig 18 we can see one successful attempt pinging one of the other devices along with one unsuccessful attempt.
Figure : Unsuccessful 'pinging' another network device
Figure : Successful 'pinging' of two devices on the LAN
On the desktop of one computer a file was created which contained a Microsoft word document with a simple one line sentence typed on it. The settings of this document were then changed to allow it to be read/write. This means when the document is opened from another computer it can be edited and then saved. When re-opened on another device on the network it is shown to have been altered. This document can again be edited saved and reopened to show the altered version; this confirms the data has been transferred over the network.
3.4 Using a switch along with Client/server:
Following a couple of days transferring and editing data with use of the router, the project was to progress with the incorporation of a switch which would replace the router currently being used. The switch is also a device used to connect multiple computers on a network namely LAN’s. With the use of the switch five computers were connected over the LAN. One computer was to act as a dedicated server and the other four computers would be acting as clients. The aim would be to make a document available from the server with each client on the network given permission to take the document, change it and re-save it back to the server without having to download it and save it to their own device first. The same procedures should be followed as were previously with the router: disable firewalls >> disable wireless functions >> assigned static IP address.
3.5 Filezilla:
Filezilla is an open source software package which can be downloaded from: filezilla-project.org.
Both version are required Filezilla-client and Filezilla-server and should be downloaded separately.
3.5.1 Filezilla Server:
The Filezilla server package is used only with the computer designated to be the main server. The four other computers were to install the Filezilla client package and would be set up as the four clients on the network.
When connecting to the server the IP address of the server was set to 127.0.0.1. This IP address is a loop-back feed with its main function for testing of networks, this will allow for packets of data to be sent over the network. If one of the clients receives error data they can drop the packets and not answer them.
Open the Filezilla server package >> the Filezilla port number requires editing and was changer to ‘14147’ in the particular case, see Fig 19 below.
Figure : FileZilla server
Figure : FileZilla server set-up
Open the Filezilla server package >> Select the edit option on tool bar at the top left >> select users as seen in Fig 20 above. The following window will become available:
Figure : Enabling users on FileZilla server
From this window the user options are edited and confirmed. Passwords are enabled in this window any client wishing to view the shared folder will be requested to enter the password which is set here. The folders wished to be shared are also selected from within this window. When selecting the clients enter the name of the computer you wish to set as a client and not the IP address. A number of attempts were made using the IP addresses and for that reason it was initially unsuccessful.
With all clients successfully registered and allowed access, the next step is to select the file which is intended for sharing. The steps to follow are seen below in Fig 22.
Figure : Configuration of client options
Follow the steps shown in Fig 22 above. Select ‘Shared Folders’ >> Add >> browse and select the folder wished to be shared with the clients selected. Tick the boxes shown ‘read’ and ‘write’ to allow each client the option of both viewing and editing the shared folder.
The file selected contains a simple Microsoft word document for the purpose of confirming file transfer.
3.5.2 Filezilla Client:
Figure : Client devices requesting access to shared files with FileZillaWith Filezilla server now set up, open the Filezilla client package on each of the client devices. The IP address of the host device will need to be entered where requested. The user name of the device and password will also be required (this is the username and password enter when selecting clients as seen in Fig 013/014).
The ‘host’ is the IP address of the server. Passwords are not essential but one was used at the particular time shown in the picture. It helps protect the documents being shared from being corrupted. The ‘port’ number wasn’t changed and left at default ’21’ the set-up of this section is seen below in Fig 23.
The first attempt to connect between client and server using Filezilla was on the 18/10/2012, the first attempts were unsuccessful.
Figure : unsuccessful transfer of data using FileZillaC:\Users\Alan.sarah-HP\Desktop\College Folders\Project Niall Murphy\Project photo's\week4-8 filezilla tranfer etc\photo 6.JPGC:\Users\Alan.sarah-HP\Desktop\College Folders\Project Niall Murphy\Project photo's\week4-8 filezilla tranfer etc\photo 5.JPG
The reasons for the unsuccessful transfer needed to be obtained and further research into the correct set-up of the Filezilla package was required. Over the next week or so a number of different options were suggested and attempted to resolve the problems occurring.
The password was removed firstly to allow ease of access between devices. From viewing a tutorial video on YouTube: http://www.youtube.com/watch?v=5_QNHIX972
Figure : Configuring FileZilla server
It suggested changing the ‘port number which had been set to default ‘21’. The tutorial video suggested any number ranging from 2000 up as far as 60,000 would work as a viable port number.
The port was duly changed to a very random: 56,900. To change the port numbers see instructions and Fig 023 below.
Filezilla server >> edit >> settings >> general settings.
With all settings changed and believed to be correct attempts were again made to transfer the file following the same steps as previously discussed. On the 25/10/12 the file transfer from Filezilla server to Filezilla client was successful for the first time. From each of the four client devices the file was opened, the Microsoft word document contained a simple sentence typed on it. The sentence was changed and resaved. The server device then again reopened the document to view the sentence. It was seen on the server computer to have been edited externally. This step was repeated a number of times from each individual client device to confirm all client devices had access to the document and had read/write options available. The document could also be deleted by each individual client device if required. From Fig 26 below screenshots can be seen confirming the first successful transfer of data using Filezilla.
Figure : successful transfer of data using FileZillaC:\Users\Alan.sarah-HP\Desktop\College Folders\Project Niall Murphy\Project photo's\week4-8 filezilla tranfer etc\photo 9.JPGC:\Users\Alan.sarah-HP\Desktop\College Folders\Project Niall Murphy\Project photo's\week4-8 filezilla tranfer etc\photo 1.JPG
Attempts were also made to check if it is possible for a client device to edit the document while the document is being viewed by the server device. The document was opened both on a single client and also on the server.
The document was edited but this editing was not visible from the server device unless the document was closed and reopened.
Another problem encountered was that if any device was left unattended for any amount of time the Filezilla packages would automatically time out and disconnect the client device from the server host.
Figure : Timeout timeFollowing the same steps as previously seen for changing the settings of Filezilla server, the timeout time was changed from 10 to 60 seconds as seen in FIG 27.
Figure : Client/server data transferC:\Users\Alan.sarah-HP\Desktop\College Folders\Project Niall Murphy\Project photo's\week4-8 filezilla tranfer etc\photo 3.JPG
Fig 28 above shows an image taken showing two computers, one acting as the server and the other a client on the network. Files are shown being transferred, marking successful completion of this area of the networking project.
At this stage of the project we have successfully completed the following targets:
Peer-to-peer networking between two devices.
Client server networking between more than two devices.
Transfer of data using Filezilla
Transfer of data between server and multiple clients over a LAN
3.6 LabView:
Incorporating Labview into the project is one of the main criteria which were outlined during the project hand over. It was initially hoped to transfer Labview data over the network using the Filezilla package. Initially it was presumed that transferring a Labview VI over Filezilla server/client would follow the same steps as transferring a Microsoft word document. Following the same steps as previously outlined above, a small simple Labview VI was created using the Labview software package. This VI would be expanded once transfer was successful.
As previously shown with the Microsoft word file, the Labview VI was saved and inserted into a file. The file was saved to the desktop on the server computer.
On the server computer:
Open Filezilla Server
Select ‘edit’
Select ‘users’
Select ‘shared folders’
Browse computer
Select Labview file saved to desktop
Select Labview file as file wished to be shared
Add clients desired (computer name not IP address)
Tick box ‘read’
Tick box ‘write'
Figure : attempting to share Labview using FileZilla
A number of attempts were made a transferring this data over the network but was unsuccessful. With numerous changes made to the settings of both the Filezilla and Labview programmes and still no success, time was running out with the end of semester the following week. After some research and speaking with some lecturers, another way of transferring Labview VI’s over a network was suggested. Following some research and after the viewing of a number of tutorial videos on YouTube this method was attempted.
Some of these tutorial videos watched may be seen at:
http://www.youtube.com/watch?v=GTJZ6JYKaIM
http://www.youtube.com/watch?v=wyIb274Lebw
Figure : Configuring Labview VI for sharingThere also various other relative tutorial videos available on YouTube and also on the National Instruments website: http://ireland.ni.com/
The image above in Fig 30 above is a screen shot taken during the process of preparing the Labview VI created for transfer over a network. The VI created was actually shared between a number of computers in the group over a web browser using the ‘web publishing tool’ within the Labview software. A step by step guide of how this is achieved is given below:
Firstly create the Labview programme required.
Select tools on the open Vi page
Select ‘web publishing’
Select the VI you wish to export (shown below in Fig 31 )
Figure : Exporting Labview via a web browser
Tick ‘request control when published’ box
Press ‘next’
Enter a title you wish the VI to have when published
Press ‘next’ again
Press ‘show in web browser’
The VI will then automatically open up within a web browser and can be remotely controlled from the browser. As seen below in both Fig 32 & Fig 33.
Figure : VI created open within a Web browser
Figure : VI being remotely switched on a Web browser
The Labview programme is now being shared over a network and being remotely controlled from which ever device permission is given to. This was good progress because although an extremely basic Labview programme it teaches the lesson of how the remote controlling of Labview may be achieved. It is a simple process now to expand the Labview programme into a more substantial one and follow the previous steps of sharing it to a web browser on each individual device desired. Although the sharing of Labview over a wireless network was not a goal set out in the project brief it did provide the group with great research and gave invaluable tips on working through the settings of the Labview programme. It also helped to provide a number of hours gaining knowledge of the programme both by trial and error attempts and also from viewing the numerous videos available on the subject.
Although sharing Labview over a web browser was a mini success in terms of the project, it wouldn’t be acceptable within industry. Wireless network are seen as too insecure to be transfer important data such as plant operating procedures etc which could be run using Labview Files. Therefor transfer of Labview data over a LAN is still an outstanding requirement.
While in class during week ending 23/11/2012 the client server network was set up in the class again with one computer acting as the host along with two laptops acting as clients, and again incorporating the use of the switch. The Labview programme was set up and the project group again began an attempt to transfer the VI over the LAN. The VI was exported to a web browser page. The IP address of both client computers were then entered into ‘remote device’ which is found in the Labview settings and can be seen below in Fig 34, this allows for those two devices to interact with the with Labview programme. Only devices with an IP address verified may interact with the Labview programme. With the VI open on the server computer this interaction was seen to take place. As a client pressed the switch to operate the light, it would illuminate on the server computer. If a client computer turned off the light from their device the light was seen to be turned off on the panel shown on the server computer. As each client device interacts with the programme it is only allowed to do so for a designated period of time. If the client did not interact with the server during that time, the control of the programme is then passed onto the next client. This process will repeat through all clients on the network. This shows that the programme is using the ‘Token Ring’ protocol. The Token Ring protocol is a protocol where a node is allowed to communicate only once that node is in possession of the ‘Token’. If the node has data to transmit it will be allowed do so only when in possession of the token. If the node has no data to transmit at that particular time the token will be passed around the ring until a node wishing to transfer data is found. This was repeated a number of times with both clients which were connected to the network. This confirmed the interaction between the Server panel and the two remote devices on the LAN, which was exactly the desired goal. The Labview programme will now be expanded to incorporate a simulation of an actual process which would be used in the control room of a modern manufacturing plant etc. It will incorporate the simulation of motor control along with possibly temperature controls among other devices.
Figure : configuring client/server to control Labview over LANC:\Users\Alan.sarah-HP\Desktop\photo.JPGC:\Users\Alan.sarah-HP\Desktop\4.JPG
Following on into the second semester of the project the focus would now be moving away from Labview and focusing on a number of networking protocols intended to be incorporated into the project. A list of protocols was assigned to the project and each member was required to research and learn how to incorporate their own designated protocol into the project. The following protocols were to be incorporated:
RS-232 communications protocol
CAN Bus
Modbus communications protocol
These protocols will need to communicate with one another via an Arduino micro controller and a switch, and provide feedback to a server device which in turn will be controlling a Labview simulator.
The author of this report was assigned the Modbus protocol to research and understand how to implement it into the project. With the project in semester one being a group project, it would now become a more individually focused one. Each member would need to work alone on their particular communication protocol both in terms of research and implementation. Weekly meetings are held between all members to discuss progress and plan how to meet the future target for the project.
3.7 Arduino micro-controller:
Firstly however each member of the project also needed to acquire the knowledge of how to communicate between the Labview package and the Arduino microcontroller. From researching the Arduino website and also watching tutorial videos available on YouTube and at: http://playground.arduino.cc/
The first aim was to write a small programme for the Arduino which would allow for communication from Labview to the Arduino, and also from the Arduino back to Labview. This would simply show that we could read from the Arduino and write to the Arduino. The simplest way of representing this was to incorporate an LED and a number of wires which could be opened and closed to simulate the opening and closing of a switch. A Labview VI was created with a Boolean and switch also, when the switch was pressed on the Labview package this would operate the LED which was wired back to the Arduino using a USB port cable. This process can be seen below Fig 029 which was taken during the process.
Figure : LED being switched from Labview via ArduinoC:\Users\Alan.sarah-HP\Desktop\2.JPG
Figure : Arduino being controlled via LabviewFrom Fig 36 below the Labview programme created can be seen, also shown is the image taken showing wires operating as a switch to activate a Boolean on the Labview VI.C:\Users\Alan.sarah-HP\Desktop\3.JPGC:\Users\Alan.sarah-HP\Desktop\7.JPG
A number of other Arduino projects were also built and operated to gain knowledge into how to programme the Arduino etc. Most of the projects built can be found at: http://arduino.cc/en/Tutorial/HomePage
These projects provide the user with code needed to write the programme and provide an excellent starting in point for learning how to write coding for the Arduino.
An example of one project created can be seen at: http://www.youtube.com/watch?v=rMrpNjlpqZI
/*
Fade
This example shows how to fade an LED on pin 9
using the analogWrite() function.
This example code is in the public domain.
*/
int led = 9; // the pin that the LED is attached to
int brightness = 0; // how bright the LED is
int fadeAmount = 5; // how many points to fade the LED by
// the setup routine runs once when you press reset:
void setup() {
// declare pin 9 to be an output:
pinMode(led, OUTPUT);
}
// the loop routine runs over and over again forever:
void loop() {
// set the brightness of pin 9:
analogWrite(led, brightness);
// change the brightness for next time through the loop:
brightness = brightness + fadeAmount;
// reverse the direction of the fading at the ends of the fade:
if (brightness == 0 || brightness == 255) {
fadeAmount = -fadeAmount ;
}
// wait for 30 milliseconds to see the dimming effect
delay(30);
}
The code above needs to be entered into the Arduino and the circuit needs to be designed as shown below in Fig 37.
http://arduino.cc/en/uploads/Tutorial/simplefade_pin9_schem.png
Figure : Fade circuit constructed
Figure : schematic referenced to build fade circuithttp://arduino.cc/en/uploads/Tutorial/simplefade_bb.png
Numerous other projects were built using the codes provide from the Arduino website. These were highly beneficial in providing a background in code writing for the Arduino microcontroller.
3.8 Modbus Protocol
The writing of the Modbus code is something which now needs to be learned and transferred into building a project cable of communicating with Arduino. Once communication with the Arduino via Modbus is achieved an Ethernet shield will then be used convert the numerous protocols into Ethernet language which will communicate with the Labview via the switch.
Modbus is an open protocol, which is free for manufacturers to use without the need for paying of royalties. Modbus has become has become a standard communication protocol within industry and is now the most commonly available means of connecting industrial electronic devices. It is used widely by manufacturers in many industries.
Modbus protocol is typically used to transmit signals from instrumentation and control devices back to a main controller or data gathering system. For example a system which measures temperature and humidity and communicates the results back to a computer or device. Modbus is often used to connect a supervisory computer with a remote terminal unit (RTU) in supervisory control and data acquisition (SCADA) systems.
3.8.1 How Modbus works:
Modbus is transmitted over serial lines between devices; the simplest version would be to set up a serial cable to connect between the serial ports of two separate devices. One device will be the master and the other will be a slave. Data is sent as a series of ones and zeros which are known as Bits. Each bit is sent as a voltage, the zeros are sent as a positive voltage while the ones are sent as a negative voltage. These bits are sent very quickly, typical transmission speed is 9600 baud (bits per second).
Long strings of ones and zeros are difficult to read, so these are combined and shown in Hexadecimal. Each block of four bits is represented by one of the sixteen characters from 0 to F, this shown below in the form of a table.
0000
0
0001
1
0010
2
0011
3
0100
4
0101
5
0110
6
0111
7
1000
8
1001
9
1010
A
1011
B
1100
C
1101
D
1110
E
1111
F
Each block of eight bits is called a Byte. Each byte is represented by one of the 256 character pairs from 00 → FF.
3.8.2 How is data stored in Modbus?
Information is stored in the slave device in four different tables. Two of the tables are used to store on/off discrete values which are known as coils. Two other tables are used to store numerical values which are known as registers. Each table has 9999 values; each coil or contact is one bit and is assigned a data address somewhere between 0000 and 270E. Each register is one word which equals 16 bits or 2 bytes.
Coil Register Numbers
Data Address
Type
Table Name
1-9999
0000 to 270E
Read/write
Discrete output
10001-19999
0000 to 270E
Read/write
Discrete input control
30001-39999
0000 to 270E
Read/write
Analogue input registers
40001-49999
0000 to 270E
Read/write
Analogue output holding registers
Coil/register numbers can be thought of as location names since they do not appear in the actual messages. The data addresses are used in the messages. For example the first holding register which is number 40001 has the data address 0000. The difference between these two values is what is known as the offset. Each table has a different offset 1, 10001, 30001 and 40001.
3.8.2 What is the slave ID?
Each slave in a network is assigned a unique unit address from 1 to 247. When the master requests data, the first byte it sends will be the slave address. This way each slave will automatically know after the first byte whether or not to ignore the message.
3.8.3 The Function code
The second byte which is sent by the master is what is known as the function code. This number will tell the slave which table is required for it to access. It will also tell whether it needs to read from or write to the table.
Function Code
Action
Table Name
01 (01 HEX)
Read
Discrete output coils
05 (05 HEX)
Write single
Discrete output coils
15 (0F HEX)
Write multiple
Discrete output coils
02 (02 HEX)
Read
Discrete input coils
04 (04 HEX)
Read
Discrete input registers
03 (03 HEX)
Read
Analogue input registers
06 (06 HEX)
Write single
Analogue input registers
16 (10 HEX)
Write multiple
Analogue input registers
3.8.4 What is CRC?
Cyclic Redundancy Check is a way of monitoring error detection by adding two bytes to every Modbus message. Every byte in the message is used to calculate the CRC. The receiving devices also calculate the CRC and then compare it to the CRC from the sending device. If even one bit of the message is sent incorrectly the CRC’s will be different and thus will result in there being an error.
Chapter Four:
Results
Results
4.0.Intro
Throughout the various stages of this project there were numerous results obtained, not all of which were positive. In the following chapter we will discuss some of the results produced throughout the course of the project. There were goals set out from the beginning and targets to be met right from the early research days.
4.1 Physical Construction of a LAN
4.1.1 Peer-to-peer
The first result was the successful research, design and construction of a peer-to-peer network which was constructed in the project workshop. This gave the project group an introduction into the world of computer networking and the vast array of terminology required to understand in the networking sector. The LAN was created initially with only two clients. A Microsoft word document was created and transferred between the two devices. Although a relatively simplistic operation it would not have been possible for any project member prior to commencement of the project. This was the first time data transfer between clients was successfully achieved and gave the group a solid foundation from which to continue.
4.1.2 Client/Server
A client/server network was the next focus of the project was successfully designed and constructed following extensive research into the design and requirements for such a network. The aim at this stage was to transfer data between a server and two or more clients. The network was constructed and again a simple Microsoft word document was transfer between all clients. Editing of the document was shown to take place between clients which again highlighted the capabilities of the network with further expansion
4.1.3 Pinging and File Transfer
After researching the procedure for ‘pinging’ between devices this process was implemented to show how to check for data transfer details and whether or not successful data transfer between IP’s was occurring.
4.2 Switch device
A switch was used to replace the router previously used; this was to allow for expansion of the network to incorporate further clients. The switch now enabled for the connection of five clients on the network. This provided a demonstration of how devices may be added to the LAN using switch to vastly increase the network size.
4.3 FileZilla Client/Server
After installation of the software the transfer of data using the FileZilla client and FileZilla server packages was successfully completed.
4.4 Labview
After design of a Labview process to simulate a process in modern industry the data was successfully transferred to other devices with the means of a Web browser. By showing how Labview content could be shared via the internet it provided a means of remote controlling of the process. This remote controlling of a process can be used in modern factories and other industries to provide out of hours control of systems and so on.
The Labview software was then successfully transferred over the wired LAN created. Using the internal network allowed for far greater security of the system and this would be the means used in modern factories where the consequences of data theft would be extremely worrying.
4.5 Arduino micro-controller
Numerous Arduino projects were created and completed which gave a lead into programming language such as C and C++.
4.6 Protocols
Knowledge of the fundamentals of numerous protocols was obtained through the vast research completed, most notably the Modbus protocol which is one of the most currently relative protocols in today’s modern industry.
4.7 Other
There were numerous other results obtained and goals achieved throughout the duration of the project so far. The main results achieved as listed above were the ones chosen to give particular highlight to. However from the amount of research undertaken and knowledge obtained it is fair to say there have been many more individual results for the author of this report. An introduction into a new sector has been provided and a solid foundation has been laid on which to expand from.
Chapter Five:
Conclusions
Conclusion
Upon completion of the project a vast new previously unknown sector has become a sector the author is now deeply interested in. After providing a great knowledge foundation from which to expand from the author expects to continue exploring the topics covered in this report. As the networking sector is becoming a major factor within modern industry it has become apparent over the course of this project that networking is vital to modern companies.
Although on the whole the project has been largely successful in completing the criteria given, there have been some low points throughout its duration as was to be expected. A lot of time had been wasted at the project outset with the focus of cable making and researching of such a slow process when realistically anyone repeating the process could simply purchase such items. With the individual sections of the project where each member was given a protocol to learn and understand its implementation, this research may have been needed to begin at an early stage. A lot of time has been dedicated to acquiring the knowledge for the implementation of the Modbus and with the project nearing its completion there is a lot of work still to be carried out.
If starting this project again a number of changes would be made to the procedure which was followed on this occasion. As previously stated time management issues were clearly encountered and would be re-addressed. For example a lot of class time was waste in the early weeks on building the LAN networks and transferring documents etc repaeatedly. Once the process had been completed the project group shouls have immediately progressed to the next objective where as in reality the same processes were being repeatedly repeated. This was mainly due to confidence in the goals achieved. It was seen that the project grouped needed to continually repeat the steps to verify the results achieved in order to gain confidence in the sector. Although this reassurance the goal has been achieved is not completely a negative factor it did waste time considering the time-scale available to complete the entire project.
Chapter Six:
References

Warning! This essay is not original. Get 100% unique essay within 45 seconds!

GET UNIQUE ESSAY

We can write your paper just for 11.99$

i want to copy...

This essay has been submitted by a student and contain not unique content

People also read