Plc July 2008 Session Set Special

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GMI G e r m a n - M a l a y s i a n

I n s t i t u t e

I N D U S T R I A L D I P L O M A P R O G R A M M E

FINAL SEMESTEREXAMINATION

A c a d e m i c P e r i o d : J u l y 2 0 0 7

Subject : PROGRAMMABLE LOGIC CONTROLLERS

Code : IAT 0912

Duration : 3 HOURS

Prepared By : SYED NIZAM SYED IDRIS

Total Marks : 100

GENERAL INSTRUCTIONS:

Write down clearly (with capital letters) your name, trade,group and the date of examination at the bottom of this page.

Do not open this question booklet until you are told to do so bythe invigilator.

Read the specific instructions and questions carefully before

answering.

This question paper consists of 14 printed pages including this page.

Student’s Name :

Student’s I/D No. :



IAT 0912 PROGRAMMABLE LOGIC CONTROLLERS

Semester/Trade/Group

:

Date :

Section A

Answer all questions using the OMR sheet provided.

Please shade your answers clearly on the OMR sheet by using only 2Bpencil or black ball pen.

1. In the following PLC block diagram, item (X) and (Y) represents

A. Central Processing Unit and Output ModuleB. Output Module and Central Processing Unit

C. Expansion Module and RAMD. EEPROM and RAM

2. The component of a PLC which stores and execute the main program is ________.

A. CPUB. Programming DeviceC. Input/Output ModuleD. Operator Interface

3. A type of memory which can be read from but not written to is called

A. RAMB. Read/Write memoryC. ROMD. EEPROM

4. A switch or a pushbutton is ____________.

A. a digital input deviceB. an analog output device

C. a digital output deviceD. an analog input device

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Copyright of German Malaysian Institute. All rights reserved.

InputModul

e(X) (Y)

ProgrammingDevice

OperatorInterface




5. __________ is a PLC programming language that uses componentsresembling elements used in a control line diagram.

A. Ladder DiagramB. Statement ListC. Function Block DiagramD. Process Graph

6. Which of the following is not required when creating or changing a PLCprogram?

A. PLC

B. Programming DeviceC. Programming SoftwareD. Printer

7. Which of the followings is not available on Siemens PLC CPU 315-2DP?

A. Status IndicatorsB. Mode SwitchC. Programming PortD. Network Port

8. A digital module for S7-300 PLC can have a maximum of _____ bits of digital terminal.

A. 32B. 16C. 8D. 4

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9. For the following ladder diagram, select the most suitable statementwhich describe its operation.

A. A continuous signal at contact I0.0 and I0.1 is needed tocontinuously on the coil Q0.0

B. With the PLC port I0.1 connected to the normally closeswitch, a short pulse of signal at contact I0.0 will latchedcoil Q0.0

C. With the PLC port I0.1 connected to the normally openswitch, a short pulse of signal at contact I0.0 will latchedcoil Q0.0

D. With the PLC port I0.1 connected to the normally closeswitch, a continuously signal at contact I0.0 will latchedcoil Q0.0

10. Which of the followings is not a part of a PLC scan?

A. Read inputsB. Reset all counters and timersC. Execute programD. Update outputs

20 MARKS

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Section B

Complete the following ladder diagram by labelling the correct symbolic

addresses for each contact and output(coil) base on the given symbolinformation.

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20 MARKS

Section C

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Please answer in the blank space provided below the questions.

Problem Definition (Refer to the machine diagram to clearly understand the system operation).

• This machine is used to mix 2 types of liquid and then drain it to anothersystem.

Initial Condition

• Initially, before the start button is pressed, all the valves are closed.

• There should not be any liquid in the tank, TLB1 and TLB2 signal should beoff.

• The stirring motor M, should be stationary, not turning.

• Indicators and buzzers should be turned off.

Process Sequence

1. As the PB1 is pressed, the machine will open valve MV1 and also turn onthe indicator PL to show that the machine is running.

2. When the first liquid into the tank reaches the level sensor TLB2, a timer isstarted.

3. When the timer reaches 10 seconds, the valve MV1 closes and valve MV3opens. Here the second liquid is channeled into the tank. Also at this pointthe mixer, stirring motor ‘M’ will start turning.

4. After the combination of both liquids reaches the level sensor TLB1, thevalve MV3 closes and after 5 seconds the valve MV2 opens. Here the mixliquid is channeled to another system.

5. 10 seconds after the liquid level falls under the level sensor TLB2, thevalve MV2 closes and the stirring motor stops.

6. Next, the valve MV1 opens again and the whole cycle is repeated again for2 cycle run.

7. After the 2 cycle run, all the valves are closed and the motor stopped, theindicator PL will be flashing and the buzzer will give a warning pulse of 2seconds on and 1 second off. This will indicate that the tank need cleaningbefore can be used again.

8. By pressing the ‘Stop’ button, the machine will stop all its operation, after1 cycle is completed.

9. Although in the diagram it is not drawn, please include an ‘Emergency

Stop’ button to stop the operation of the machine immediately.

Indicators

1. Lamp PL indicates the machine is in operation (from start until the end of the process).

2. Lamp PL flashing and buzzer, indicates that the tank need cleaningbefore any further operation.

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Process Schematic

NOTE;

Valve type:If current is not flowing through the coil, the valve will CLOSE.If currently is flowing through the coil, the valve will OPEN.

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1) Complete the given assignment list/symbol table below.

INPUTS OUTPUTSSymb

ol

Address Description Symbo

l

Address Description

Start Operation Valve liquid 1

Stop Operation Valve liquid 2

Level Sensor,bottom of tank

Valve for drainage

Level Sensor, topof tank

Stirring Motor

S7 I0.4 Emergency Stop Lamp Indicator

Buzzer

10 MARKS

2) Draw the PLC wiring diagram.

10 MARKS

3) Complete the Sequence Step Diagram below.

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The assessment for the ladder diagram will be based on the followings;

SPECIFICATION Max.Marks

MarksAwarde

dProgram Structure

Program is develop based on the Sequence StepDiagram

4

Sequence process programming format 2Actuation process format 2

System OperationIn order to activate the system it should be in theInitial Condition.

2

If all the initial conditions are met, and by pressingthe start button, MV1 will open.

2

Then once TLB2 detects the liquid and after 10seconds, MV1 close and MV3 open. Stirring Motoralso turned on.

3

Then once TLB1 detects the liquid, and after 5seconds, MV3 close and MV2 open. 2

Then once TLB2 detects the liquid, and after 10seconds, MV2 close, the stirring motor stops and acounter is triggered.

4

The cycle will start again for 2 more cycle. 3

When the operator presses the “Stop” button, themachine will complete 1 cycle before stopping. 2

Lamp PL illuminates during normal running, andstarts flashing after 3 cycle run.

2

Buzzer sounds during after 3 cycle run. 2

30 MARKS

LADDER DIAGRAM FOR Section B, Q4

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Plc July 2008 Session Set Special