Master of Engineering Industrial Automation Solutions

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Master of
Engineering
Industrial
Automation
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Table of Contents
Question 1: Standard Languages and Scan Cycle...............................................................................................4
Question 1 (a):.....................................................................................................................................................4
Question 1 (b):....................................................................................................................................................4
Question 2:..............................................................................................................................................................4
(a) The concept of current sourcing input module and its wiring is described as........................................4
(b) Wet relay output......................................................................................................................................4
(c) The behavior of a PLC is termed to be real time....................................................................................4
(d) Ladder code in codesys...........................................................................................................................5
(e) Instantaneous and memory elements of PLC..........................................................................................5
Question 3:..............................................................................................................................................................6
(a) Program 1: OUT1 is active only if all three internal relays are active simultaneously..........................6
(b) Program 2: OUT2 is set if any one or more internal relays are active, otherwise OUT1 is reset...........6
Question 4:..............................................................................................................................................................6
(a) In making this truth table the reference is adopted from [2]...................................................................6
(b) Re-Program in CodeSys..........................................................................................................................6
Question 5:..............................................................................................................................................................7
a) Fire alarm implementation..............................................................................................................................7
b) Visual simulation and results..........................................................................................................................7
Question 6:..............................................................................................................................................................8
(a) Program to Calculate Output “z”............................................................................................................8
(b) LD & ST Function Blocks......................................................................................................................8
(c) Proof that 5+23+2 = 37...........................................................................................................................8
Question 7:..............................................................................................................................................................9
(a) Reason to use switch to choose between run and idle modes.................................................................9
(b) Why do many modern PLC’s have a coin battery?................................................................................9
(c) Principle Differences..............................................................................................................................9
Cyclic scan......................................................................................................................................................9
Free-running scan............................................................................................................................................9
Free-running scan is the scan which is applied at specific body of the program which execute in the body.
In this scanning, program is applied more than one and this process is slower than the cyclic scan.............9
Event-triggered scan.......................................................................................................................................9
Question 8:..........................................................................................................................................................9
(a) Hierarchy.................................................................................................................................................9
(b) Language Belongings..............................................................................................................................9
References:............................................................................................................................................................11

List of figures
Figure 1: LD Example of codesys..........................................................................................................................4
Figure 2: visual simulation of above example of light lamp..................................................................................4
Figure 3: codesys example when switch is off.......................................................................................................4
Figure 4:codesys result when switch is off.............................................................................................................4
Figure 5: set/reset example of light with switch.....................................................................................................4
Figure 6: out1 implementation................................................................................................................................5
Figure 7: Out2 implementation [1].........................................................................................................................5
Figure 8: Question 3 with structure text out1.........................................................................................................5
Figure 9: Question 3 with structure text Out2........................................................................................................6
Figure 10:fire alarm above condition is implemented............................................................................................6
Figure 11:fire alarm visualization in the foromof lamp light.................................................................................6
Figure 12: z output is implement in structure text language...................................................................................7
Figure 13:results of the above question is mentioned.............................................................................................7

Question 1: Standard Languages and Scan Cycle
Question 1 (a):
Question 1 (b):

The execution of program is comprised on the input scanning, program update and output
scanning. A complete cycle is run in such a way that repeats its self for many time in milliseconds is
called scan cycle. The PLC device is same for all kind of languages run in PLC compiler, for instance,
codesys.
Question 2:
(a) The concept of current sourcing input module and its wiring is described as.
PLC compiler has two sources one is called source input and second is called sink input; both are
used to control the current of the components. Sourcing input digital module is used to provide the
voltage to the component and directly wire with the input devices with the command of set coil and
used digital value of voltage to start. For instance, if the diode is connected with the source input
module then the second side will be connected with the sink of this module [3].
(b) Wet relay output
Wet relay is connector with the power applied which usually use to energize the solenoid, light
etc. this relay is available in the different voltage like 5v, 12v, 24v and also available in 120v to 220v.
Moreover, wet contact is the relay which allow to pass the voltage as soon as possible and use to
close the circuit rapidly.
(c) The behavior of a PLC is termed to be real time.
In real time live statue of the compiled program can be monitored without attaching any
sensors and visualization. This behavior provides me ease to understand the working of each
component attached with the PLC program.
(d) Ladder code in codesys
Figure 1: LD Example of codesys

Figure 2: visual simulation of above example of light lamp.
Figure 3: codesys example when switch is off
Figure 4:codesys result when switch is off.
Figure 5: set/reset example of light with switch.
(e) Instantaneous and memory elements of PLC
The main difference between the instantaneous and memory element is that the value of memory
store element cannot be changed when the program is compiled on the other hand the instantaneous
values can be change when the program is compiled. The memory stored element provides active
behavior and instantaneous values provide active behavior [1].
Question 3:
(a) Program 1: OUT1 is active only if all three internal relays are active simultaneously
Figure 6: out1 implementation

(b) Program 2: OUT2 is set if any one or more internal relays are active, otherwise OUT1 is
reset.
Figure 7: Out2 implementation [1]
Question 4:
(a) In making this truth table the reference is adopted from [2]
(b) Re-Program in CodeSys
Figure 8: Question 3 with structure text out1
2.

Figure 9: Question 3 with structure text Out2
Question 5:
a) Fire alarm implementation
Figure 10:fire alarm above condition is implemented
b) Visual simulation and results
Figure 11:fire alarm visualization in the foromof lamp light

Question 6:
(a) Program to Calculate Output “z”
Figure 12: z output is implement in structure text language
(b) LD & ST Function Blocks
(c) Proof that 5+23+2 = 37.
Figure 13:results of the above question is mentioned
After the execution of above program it is concludes that the 13 is not equal to the 37 hence, L.H.S is
not equal to R.H.S.

Question 7:
(a) Reason to use switch to choose between run and idle modes
The main reason to use switch is that after the execution of program PLC starts system
immediately so, every system needs a safety switch.
(b) Why do many modern PLC’s have a coin battery?
PLC device is smart and efficient. The electronic components which are used in this circuit need constant
power to maintain its efficiency that’s why PLC needs coin battery to run continuously. Moreover, this battery
is made of lithium which gives immense power to run the load [3].
(c) Principle Differences
Cyclic scan
Cyclic scan is the process which is applied line by line repeatedly and executes the program. In this process
the whole program is scanned without any logic, firstly it scan the input and then update the output according to
the program body.
Free-running scan
Free-running scan is the scan which is applied at specific body of the program which execute in the body.
In this scanning, program is applied more than one and this process is slower than the cyclic scan.
Event-triggered scan
Event-triggered scan is the scan which is triggered for multiple times and faster than the previous
scan. The procedure of scanning applies on the specific event of the program body[4].
Question 8:
(a) Hierarchy
(b) Language Belongings
Construct IEC61131-3
LDN Ladder logic close connector

References:
[1] Slide player.com. (2019). Programmable Logic Controller - ppt download. [online] Available at:
https://slideplayer.com/slide/10782446/ [Accessed 16 Aug. 2019].
[2] Engr.siu.edu. (2019). [online] Available at: http://www.engr.siu.edu/staff/spezia/Web438B/Lecture
%20Notes/ET438B-7.pdf [Accessed 16 Aug. 2019].
[3] Help.codesys.com. (2019). CODESYS Online Help. [online] Available at:
https://help.codesys.com/webapp/_cds_st_expressions;product=codesys;version=3.5.15.0 [Accessed 16
Aug. 2019].
[4] Instrumentation Tools. (2019). plc ladder logic practice problems pdf. [online] Available at:
https://instrumentationtools.com/tag/plc-ladder-logic-practice-problems-pdf/ [Accessed 16 Aug. 2019].