Programmable Logic Controllers, SCADA and Distributed Control Systems, Industrial Data Communication

Advanced Diploma of Electrical and Instrumentation (E & I) Engineering for Oil and gas Facilities

(52684WA)

Written Assignment for Module 18

Programmable Logic Controllers

V3

The student to fill in

Assessor’s remarks

TH MODEL ERS

General Information for Candidates

How is this task assessed?

After completion of this assessment task, you will be assessed as ‘satisfactory’ or ‘not satisfactory’. You will be given feedback via Moodle and have an opportunity to submit additional evidence.

For a ‘satisfactory’ result in this task, all sections must be answered to a ‘satisfactory’  standard with a mark of 50% or above achieved.  At Advanced Diploma level a ‘satisfactory’ standard, as stipulated by the Australian Qualifications Framework (AQF), means that you will demonstrate the application of knowledge and skills:

• with depth in areas of specialisation, in contexts subject to change

• with initiative and judgment in planning, design, technical or management functions with some direction

• to adapt a range of fundamental principles and complex techniques to known and unknown situations

• across a broad range of technical or management functions with accountability for personal outputs and

• personal and team outcomes within broad parameters

Where a critical question is identified you must receive a mark of 100% for this question before a ‘satisfactory’ result can be awarded for this task.

Assessors  also make decisions based on the following considerations:

• all parts of the assessment task/s have been completed to a standard that satisfactorily meets the requirements set out in all of the assessment criteria (as set out in the unit/module outlines).

• the assessment tasks are the student’s own work, except as appropriately acknowledged by the use of referencing. 

• the evidence is recent and knowledge is up-to-date

• the evidence is consistent showing competency over a period of time suggesting sustained performance (i.e. not just a one off).      

Assessment Task Instructions:

1. The best marks can be earned by giving concise brief answers that addresses the questions as put to you.

2. The time indicated is tentative and is not meant to restrict your answers

3. The main idea behind the use of assignment questions are for you the student to learn and understand the material by reading it and answering the questions as put. Cutting and pasting from internet sites or the study material does not enhance that learning process. However, appropriate diagrams can be pasted if you cannot draw them.

4. Attempt ALL questions

5. Use this document also for furnishing your answers by typing the answers after each question without deleting the question. Use this Microsoft Word document as it stands. Make sure that you preserve the original question number format and that you don’t change the question numbers by adding extra lines or deleting existing ones.

6. Do not add extra pictures etc as Annexures but add the pictures and diagrams directly into this main answer sheet by pasting. Handrawn sketches can be inserted after scanning but please ensure that the assignment filesize does not become big (more than 10 MB).

7. Refer in the text to diagrams and pictures etc that you have drawn or pasted in. Do not only paste them into the document without referring to them in the text.

8. Finally when saving your document (must be WORD FORMAT), ensure you save the title to include your name : COURSECODE_MODULE#_ASSIGNMENT_VERSION#_YOURNAME

E.g. DME03_Module3_Assignment_v3_BOB_BROWN

1. Please ensure that all answers must be in your own words. Copying and pasting is not allowed.

2. Please ensure you sign and date the below statement to verify your assessment submission as your own material.

Module 18 – Programmable Logic Controllers

Total marks-76 Time- 2 hours

Instructions from your course instructor:

Please revisit the recordings, when a question appears problematic.

NB – Many people have taken to going to “the University of Google” to get their own answers, cut and paste them, and put them down in their assignments. I have also made use of Google, and found a great random number generator, which I can use for marking these questions, so be warned! On a more serious note, I would be looking for matters that I have discussed, and not some internet driven answers! You will be using Google at your peril, as I mark very strictly, according to my own memorandum.

Work relevant to the recording of Module 18.1 – Intro, PLC hardware, PLC software, using ladder logic, and registers

Question 1

PLC projects can be quite large, and need to be very carefully thought out. If you were to be in charge of a complete PLC project, please list and DISCUSS the major areas / groupings (at least eight) would you break the project down, into? (16)

Answer:

Question 2

There are still many sceptics, who express concern about making use of PLCs. Please DISCUSS these concerns (any four), and how you believe they have been addressed. (8)

Answer:

To eliminate the high costs associated with inflexible, relay-controlled systems.

The controller had to be designed in modular form, so that sub-assemblies could be removed easily for replacement or repair.

The control system needed the capability to pass data collection to a central system.

The method used to program the controller had to be simple, so that it could be easily understood by plant personnel.

The system had to be reusable.

Question 3

I wish to sink digital inputs (push buttons) and sink digital outputs (just normal relays), working on 24Vdc. Please provide a primitive sketch, showing the PLC as a block, in which you indicate how the devices would be coupled to external voltages, etc. (4)

Answer:

Work relevant to the recording of Module 21.2 – Good Programming habits, good installation practice, advanced PLC control, batch and sequencing and PID control

Question 4

4.1 Explain the difference betwen a BIT and a DIGIT. (2)

Answer:

A bit (short for binary digit) is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1. ... Half a byte (four bits) is called a nibble. In some systems, the term octet is used for an eight-bit unit instead of byte. A digit is an element of a set that, taken as a whole, comprises a system of numeration. Thus, a digit is a number in a specific context. ... The term "binary digit" is compressed to " bit " in computer parlance. Other numbering systems used in computing include the octal and hexadecimal systems.

4.2 What is the binary equivalent of the OCTAL number 6307? (2)

Answer:

1100110001112

4.3 What is the binary equivalent of the HEXADECIMAL number A2D8? (2)

Answer:

10100010110110002

4.4 What is the decimal equivalent of the binary number 1101 0111 0101? (2)

Answer:

344510

Question 5

List and describe any six aspects that you would deem to be important, as far as software reliability is concerned. (6)

Answer:

Software verification, factory acceptance testing, testing procedures, emulating missing hardware, emulating process response,

Question 6

List and describe any nine aspects that you would consider important, when it comes to hardware configuration. (9)

Answer:

Design phase, specify equipment phase, configuration phase, programming phase, testing phase, installation phase, commissioning phase, documentation phase.

Work relevant to the recording of Module 18.3 – Safety PLCs, data comms, IEC 61131-3, checking and testing and OPC.

Question 7

Explain what an unbalanced communication system is, and how it differs from a balanced system. (4)

Answer:

Question 8

Compare a STAR topology with a BUS topology. Also list STAR topology’s four major advantages and four disadvantages. (8)

Answer:

Question 9

List and describe three graphical languages encountered under IEC 61131-3. (6)

Answer:

Question 10

10.1 Would you describe Structured Text as a high level or low level language, and why? (2)

Answer:

10.2 Would you describe Instruction List as a high level or low level language, and why? (2)

Answer:

Question 11

What does the acronym OPC stand for, and what does it mean in a PLC PID control context? (3)

Answer: