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Name :

Roll No. : ....

Invigilator's Signature : ..

CS/B.TECH(ICE)/SEM-7/IC-702/2011-12

2011

LOGIC AND DISTRIBUTED CONTROL SYSTEM

Time Allotted : 3 Hours Full Marks : 70

The figures in the margin indicate full marks.

Candidates are required to give their answers in their own words as far as practicable.

GROUP A

( Multiple Choice Type Questions )

1. Choose the correct alternatives for any ten of the following :

10 ! 1 = 10

i) The popular field-bus networking topology is

a) Ring topology b) Star topology

c) Multi drop d) Single drop.

ii) Which one of the following is not the input of a PLC

system ?

a) Push button b) Relay coil

c) Relay contact d) Toggle switch.

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iii) Which type of isolator is generally used in I/O module

of PLC ?

a) Electrical isolator b) Optical Isolator

c) Magnetic isolator d) Electronic Isolator.

iv) IEEE 1451 connection, a network connects more than

one sensor ( or actuator ) to

a) an analog wired network

b) a digital wired network

c) a digital wireless network

d) a digital wired or wireless network.

v) In PLC limit test function is a / an

a) advance mathematical function

b) advance compression function

c) data function

d) logging function.

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vi) SCADA is used

a) to change the set point of the local controller

b) to control a closed-loop system

c) to control a open-loop system

d) all of these.

vii) Accuracy of analog PLC depends on

a) company configuration

b) user program

c) analog signal it receives

d) no. of bits of PLC in I/O module.

viii) In DDC number of controller depends on

a) no. of control loop

b) no. of manipulated variable

c) no. of measured variable

d) none of these.

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ix) When is overflow ( OV ) bit set for a PLC counter ?

a) Above + 33767 b) Above + 32767

c) Below + 34276 d) Below + 32767.

x) PLC can be used as analog PID controller. The

statement is

a) true b) false

c) ambiguous d) vague.

xi) HART protocol is used for

a) Field instruments b) DAS

c) PLC d) SCADA.

xii) Operating system configuration is usually done

a) online

b) off-line

c) either online or off-line

d) inbuilt within the system.

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GROUP B

( Short Answer Type Questions )

Answer any three of the following. 3 ! 5 = 15

2. Why is there a need of multi-loop system ? What are the

limitation with single loop control ? Explain with the help of

an example. 2 + 2 + 1

3. Explain with a neat sketch, the structure of a distributed

control system.

4. What are meant by smart valves and smart actuators ?

5. What are the different data moving programming functions in

PLC ? Describe them with ladder diagram.

6. Describe a typical PID function in a PLC with all parametrs

used including inputs and outputs.

GROUP C

( Long Answer Type Questions )

Answer any three of the following. 3 ! 15 = 45

7. a) What is PLC ? What are the advantages of PLC in

control system ?

b) What is ladder logic and how does it execute ?

c) What are the programming algorithm of DDC in three

mode PID control loop ? 5 + 5 + 5

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8. a) Explain with an example of the following :

i) DAS

ii) DDC

iii) SCADA system

iv) Data logger.

b) Discuss the principle of computer control system with

the help of functional block diagram. 8 + 7

9. a) What is the role of Digital computer in industrial

process control ?

b) Sketch and explain the memory mapping of PLC.

c) What do you mean by analog PLC operation ? 5 + 5 + 5

10. a) What do you mean by IEEE 1451 standards ? What is

the objective of IEEE standards ?

b) Discuss advantage and disadvantage of DCS.

c) What is DCS protocol ? Discuss different types of DCS

protocol. ( 3 + 2 ) + 5 + 5

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