LABORATORY ACTIVITY 2 : Simulate Analog and Digital Function Blocks
GROUP 1
BRETANIA, Josua Rama
ECONAR, Crester Vone Villanosa
MANSUETO, Judilyn Magarso
OGUIMAS, Melville June Bacalso
PEROTE, Reven Jaye Navarro
January 2023
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TABLE OF CONTENTS
Page
I.
LIST OF FIGURES ……………………………………………………
2
II.
LIST OF TABLES …………………………………….………………
2
III.
LIST OF ABBREVIATIONS …………………………….……………
3
IV.
INTRODUCTION ……………………………………………………….
4
A. Background Information …………………………………………..
4
B. Objectives ….……………………………….………………………
.
C. Materials …….………………………...…………………………..
4
V.
PROCEDURE ………………………………………………………….
5
VI.
RESULTS/OBSERVATION …………………………………………...
6
VII.
CONCLUSION ……………………………………………………...…..
10
VIII.
REFERENCE ………………………………………………………….
10
1
4
I.
LIST OF FIGURES
Page
Figure 1 - Analog I/O function block simulation sample………………….….………..….6
Figure 2 - Digital I/O function block simulation…………………………………………….6
Figure 3 - Crossing connection between Analog and Digital I/O………………………..7
Figure 4 - AND logic operator with many inputs and one output………………………..7
Figure 5 - OR logic operator with many inputs and one output………………….………8
Figure 6 - AND logic operator with two inputs and one output………………….……….8
Figure 7 - AND logic operator with two inputs and one output…………………………..8
Figure 8 - NOT logic operator with one input and one output …………………………..9
II.
LIST OF TABLES
Page
Table 1 - AND/OR logic operators simulation results………………………………….…9
Table 2 - NOT logic operator simulation results……………………………………….….9
2
III.
LIST OF ABBREVIATIONS
Abbreviation
Full description
AI
Analog Input
AO
Analog Output
DCS
Distributed Control System
DI
Discrete (digital) Input
DO
Discrete (digital) Output
FBD
Functional Block Diagram
I/O
Input/Output
IL
Instruction List
LD
Ladder Logic
PID
Pulse Input
SFC
Sequential Flow Charts
ST
Structured Text
3
IV.
INTRODUCTION
A. Background Information
Programmer have all been battling to figure out how to build massively efficient
programs over years. They encounter many problems that must be resolved when
creating software application. The client-server architecture, which serves as the
foundation for cross architectures and separates services like display, application
logic, and information management, is an example of a distributed system (Maltseva,
2018).
The previous experiment discusses the hardware and software related to the
distributed control system. The topic of software and programming is covered in this
experiment. For developing logic, a variety of computer languages are employed.
Ladder logic (LD), structured text (ST), instruction lists (IL), sequential flow charts
(SFC), and functional block diagrams are the languages mentioned in the IEC 61131
standard (FBD).
Programming in DCS typically uses Functional Block Diagrams (FBD). In
essence, such language is a visual programming language that allows users to
program objects in the structure of blocks. The blocks can then be connected in
circuit-like fashion. It outlines the connection between an input and an output. DCS
is programmed using a graphical interface. FBD can be used to build functional
algorithms as well as control schemes for a specific plant. The DCS system treats
the control modules like a distinctive element. A specific algorithm, including AI, AO,
DI, DO, or PID, as well as the data needed for the method, are contained in each
function block. Simple input conversion blocks to complicated control strategies are
all examples of function blocks (Technicals, 2022).
Instance data is used to store and handle the inputs and outputs of functions
and function blocks. They make it easier to implement systematic operations and
sequences since an instance may be made quickly. A defined function is
implemented specifically in instances (Edema, 2023). In DCS, it commonly used
library functional blocks such as Analog Input function Block, Analog Output function
Block, Discrete (digital) Input (DI) Function Block, and Discrete (digital) Output (DO)
Function Block. A single analog measurement value and its state are accessed by
the Analog Input (AI) Function Block through the AI channel. Through a specified AO
channel, the analog output (AO) function block can allocate an output value to field
devices such control valves. Together with condition varying between different states
of the field devices, the discrete input (DI) function blocks allow access to a single
digital input value. Data from the operation is taken by the digital output block, which
then writes it onto a particular digital output channel.
B. Objective
This activity aims to simulate analog and digital function blocks. Also, it aims
to achieve the following objectives:

Study various function blocks available in DCS.

Develop FBD program using basic digital and analog function blocks.
C. Materials
Using fundamental digital and analog function blocks, an FBD software may
be created. The tools required to use the program are as follows:
- Laptop
- Simulator App

Algorithm (I/O Blocks)
- AI
- AO
- DI
- DO
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V.
PROCEDURE
In this laboratory activity, software and programming concepts have been
discussed. To execute the said activity, a DCS simulator has been used that has been
provided for simulating analog and digital function blocks with the required logic
operators. There are three parts to the procedures that have been given for executing
this activity. The first part is to understand the operation of the AI and AO function
blocks; the second part is to understand the operation of the DI and DO function blocks;
and the last part is to understand the operation of the logic function block using DI and
DO as input and output, respectively.
For the first part, the AI and AO tabs under the IO tab in the upper left of the
simulator had been dragged and positioned inside the workspace. The setup was then
compiled and activated by clicking the compile and run tab. The output value of the AI
block can be altered by right-clicking the block, selecting edit, and entering an input
value in the range 0-100. Blocks can be disconnected by selecting the question mark
on the block's output side and pressing the delete key. After simulating the first part,
the clear tab was used to clear the workspace. The same procedures were used to
simulate the activity's second part, which is the DI and DO function block. The only
difference is that the output of the DO block only varies between 0 and 1 in response
to the DI block's input, which also varies between 0 and 1.
The AND, OR, and NOT logic circuits were configured for the third part of the
procedure. Two DI blocks were used as inputs for the logic circuits, and a DO block
was used for its output. The AND logic function was put in the workspace for simulation,
and two DI blocks were connected to the AND logic block. The input values of two DI
blocks had been changed by toggling DI values from 0 to 1, and the output in the DO
block had been observed. For executing the OR operator, the AND operator has been
deleted and replaced with the OR block from the logic operators. Finally, the OR block
was replaced by the NOT block from the logic operators to execute the NOT logic
circuit. This time, the input was only one from the DI block. The input value of the DI
block has been changed by toggling the DI values from 0 to 1, and the output in the
DO block has been observed.
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VI.
RESULTS/OBSERVATIONS
The first and second parts of the procedure demonstrated the functions of the
analog and digital input/output function blocks. Upon executing the analog input/output,
it can be observed that the output value of an AO block is the same as the input value
of an AI block. The output value is the same as the input value, as with digital input and
output. The only difference is that the analog input can vary from 0 to 100, while the
digital input can only vary from 0 to 1. It can also be observed that an analog input can
only be connected to the analog output, and a digital input can only be connected to the
digital output. The results are shown in the figures below.
Figure 1. Analog I/O function block simulation sample
Figure 2. Digital I/O function block simulation
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Figure 3. Crossing connection between Analog and Digital I/O
The third part of the procedure demonstrated the operation of the AND, OR
and NOT logic function blocks. These logic operators use digital input and also make
a digital output. Upon exploring the DCS simulator, it can be observed that the AND
logic operator can have many inputs with only one output. Same with AND logic
operator, OR logic operator can also have many inputs with only one output. But for
simplicity, the activity only requires two inputs for AND/OR logic operators. Unlike the
previous operators, the NOT logic operator requires only one input and produces only
one output in digital form also. Documentations and results for the said observations
are shown in the figures below.
Figure 4. AND logic operator with many inputs and one output
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Figure 5. OR logic operator with many inputs and one output
Figure 6. AND logic operator with two inputs and one output
Figure 7. AND logic operator with two inputs and one output
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Figure 8. NOT logic operator with one input and one output
Various results are recorded based on the observations from the procedure
and were summarized in the tables that is shown below.
Logic Operator
AND
OR
DI1
DI2
0
0
1
0
1
1
0
0
1
0
1
1
Table 1. AND/OR logic operators simulation results
Logic Operator
NOT
DI
1
0
Table 2. NOT logic operator simulation results
9
DO
0
0
1
0
1
1
DO
0
1
VII.
CONCLUSIONS
In this activity, the basic FBD program has been developed using basic digital
and analog function blocks with basic logical operators AND, OR and NOT. As being
discussed in the introduction, Functional Block Diagrams are commonly used in DCS
programming (FBD). In essence, such a language is a visual programming language
that allows users to create objects with a block structure. After then, the blocks can be
joined in a circuit-like method. Analog Input function Block, Analog Output function
Block, Discrete (digital) Input (DI) Function Block, and Discrete (digital) Output (DO)
Function Block are the basic functional blocks were used in this activity.
Based on the results and observations, the Analog Input (AI) Function Block uses
the AI channel to access a single analog measurement value and its state. The analog
output (AO) function block can assign an output value to field devices such as control
valves through a defined AO channel. The discrete input (DI) function blocks, when
combined with condition altering between multiple states of the field devices, give
access to a single digital input value. The digital output block receives data from the
operation and publishes it to a specific digital output channel.
A logical operator is a symbol or word used to connect two or more expressions
such that the value of the compound expression produced depends only on that of the
original expressions and on the meaning of the operator. Common logical operators
include AND, OR, and NOT (Busbee & Braunschweig, 2021). According to the summary
results and observations, the AND logic operator returns 1 if all component conditions
are 1, and 0 if at least one of the inputs is 0. The OR logic operator returns 1 if at least
one component has a value of 1 and 0 if all component conditions have values of 0.
Finally, the NOT logic operator returns 1 if the value of the input is 0 and 0 if the value
of the input is 1.
VIII. REFERENCES
Edema., V. (2023). Function Block Programming and Troubleshooting. SolisPLC.
Retrieved January 28, 2023, from https://www.solisplc.com/tutorials/Mitsubishi GX
Works2 Function Block Programming and Troubleshooting (solisplc.com)
Maltseva., D. (2018). 5 concepts of Software Distributed Systems. Benefits of
Distributed Architectures. DEV Community. Retrieved January 28, 2023, from
https://dev.to/dianamaltseva8/5 concepts of Software Distributed Systems.
Benefits of Distributed Architectures - DEV Community
Technicals., N. (2022). Logical Function Blocks available in DCS. nandantechnical.
Retrieved
January
28,
2023,
from
https://www.nandantechnicals.com/2022/07/Logical Function Blocks available in
DCS (nandantechnicals.com)
Leroy, K. & Braunschweig, D. (2021). Programming Fundamentals. Retrieved January
28,
2023,
from
https://press.rebus.community/programmingfundamentals/chapter/logicaloperators/#:~:text=A%20logical%20operator%20is%20a,AND%2C%20OR%2C
%20and%20NOT.
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