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Automatic Control System
VII.
Controller
transmitter
actuator
Structure of control system
Process
the name of mathematical
model of the plant
Material flow
sensorstransducer
actuatingunit
actuatingdrive
controller
operator desk
Visualisation softwareSCADA (Supervisory control and data acquisition)
Simulation software
Control software
Standard signals
Variables
Standard industrialI/O interface
Process controller and typical application field
• Process controllerready to use for industrial control and it’s possible the hardware redundancy and integrate the functionality of control and SCADA software.
• Application fieldprocess industry applications (paper, primary metals, food processing, and so on.)batch-type control (chemicotechnology, pharmaceutic chemistry, or injection molding machines, and so on.)
• Programmabilitystandard control languages IEC1131-3 and SCADA depending of factory
PLC familyes
• Control relays8-20 I/O, limited memory size, only LD programming languages with limited and not standard instructions.
• Compact PLC12-32 I/O, normal memory size, standard IL, LD, FBD programming languages with limited instructions.
• Modular PLC with compact unitflexible arrangement up to 800 I/O, different memory size, standard IL, LD, FBD programming languages.
• Modular PLC with rack systemHigher I/O number, memory size, CPU frequency, network ability. All standard programming languages are used.
Structure of modular PLCProgramming device
CPU module
Local extension I/O module
Network station Remote extension I/O module
MCC
Variable Speed Drives
S800 I/O
S900 I/O (Ex)
Workplaces
Control Network
Remote Clients
System Servers
Fieldbus High Speed Linking Devices(FF HSE/H1, PB DP/PA)
Process Automation Process Automation and Safety
Operator EngineeringMaintenance
Safety
Network arrangement
© AB
B G
roup
April 19
, 202
3 | Slid
e 8
CPU Terminal base
(“TB 711F”)
CPU (“PM 783F”)
Local I/O Modules (Up to 8)
I/O Terminal Units
(up to 8)
FBP (Field Bus Plug) *
RS232/485
DIAG
RS232/485
SER (MODBUS)
Field Bus Coupler Connector *
Ethernet
(RJ-45)
24 VDC
Power connector
AC 700F kontroller V9.1
Industrial software
• Simulation softwareFacilities: Involving differential equations, matrix, etc. Converting between frequency and time domain. Charting functions.Creating block models.
• Control softwareContent of control task for industrial computer (process control), or intelligent devices in laboratory (scope, frequency generator, power supply, etc.)
• Visualisation softwareInstead of classic operator desk (push button, dial indicator)
Control software
Control software needs a model of the process• Define correct interface between process and controller.
(using standard signals)
• Dividing into simpler part of the process.
• Choosing control strategies.
• Creating control task, and define the parameters.
Standard industrial I/O interface for signals
Digital I/O
• galvanic isolation
• 24 VDC logic (0 -7 VDC , 14 - 30 VDC)
Analogue I/O
• Usually no galvanic isolation
• Typically: 4-20 mA signal area
• Typically resolution: 12 bit
Dimensionless technique
)({dim}1
{dim}){dim}( min twwtw
Controlled, measuredvariable
feedbacksignal
actionsignal
manipulatedvariable
A/D conversioncontrol task
D/A conversion
max
min
20 mA
4 mA
max
min
20 mA
4 mA
Domain ofvariability
Program structure of PLC control program
Deafault task
Periodictask
Eventtask
Systemtask
Priority
Program A1
Program An
Program E1
Program En
Program Rn
Program R1
Program Pn
Program P1
Function block 1
Function block N
Function N
Function x
Function 1
Data FB1/1Data FB1/2Data FB1/3
The system programs handle the error, keep the connection with operator, and so on.
Function block 2
Programs, function blocks, functions
• The programs can be written any standard languages. Different languages can be used in the project.
• The function blocks and the function are well tested subprograms.
• The function blocks have more input and more output variables, which can be catch from any programs.
• The functions have more input and one output variables. The output variables appear in the working register of CPU and needs handle.
How the programs use the CPU
t
t
t
t
D
P
E
S
A1A2A3A1
P1
A2A3A1A
P
E1
P
AAA3A1A2A3A1
R1
A3A1A2A3A
Cyclic processing of the user programnot use loop instruction (for, until..)
at the end the program the processing starts again automatically
Write data
interrupt
Standby PLC
selftest
Process user program
Read data
The standard control languagesIEC1131-3
• Structural Textsimilar to QuickC
• Instruction Linesimilar to assembly
• Ladder Diagramgraphical language similar to contact plan
• Function Block Diagramgraphical language similar to digital circuit plan
• Function Chartgraphical language and text languages by IEC848 standard
Structure of Instruction line
Label InstructionSymbolic name
for variableComment
These are always requiredIt is used like the target of the jump instructions. It relates to the variable.
Jumps Label
CallsSymbolic name
for function block
or function
Structure of jump’s instructions
A
CB
D
yes
label yes
yes jump conditional
A
no
label unconditional jump
no
jump unconditional
B
C
D
Structure of Call’s instructions
Userprogram
Functionblock
Data_1
Data_2call name
The same type of function blocks or functions can be called more timeswith different name and so data block.
The call’s instructions can be used inthe function block program too.
return
Instructions of IEC1131-3
• LD, LDN
• S, R
• ST, STN
• AND, ANDN
• OR, ORN
• XOR, XORN
• LT, LE, EQ, EN, GE, GT
• JMP, JMPC, JMPCN
• CAL, CALC, CALCN
• RET, RETC, RETCN
all variables
bool variables
all variables
bool variables
bool variables
bool variables
all variables (the result is bool)
label
name of function block or
function
Store, Set, Reset output instructions
• Store STIn all scan the output result depends on the actual value of the contacts.
• Set SIn the first scan when the logical result of contacts actual value equals true the output register (variable) is set high, and remains in this state independent the contacts actual value until a reset instruction.
• ResetRIn the first scan when the logical result of contacts actual value equals false the output register is reset
Variables of IEC1131-3• BOOL
• BYTE, WORD, DWORD
• integer (INT), short integer (SINT), double integer (DINT), unsigned integer (UINT), ...
• REAL
• TIME
• DATE
• TIME_OF_DAY
• DATE_AND_TIME
• STRING
bool variables
bit sequence variables
digital variables
real number
T#0h0m0s0ms
D#1900-01-00 (YYYY-MM-DD)
TOD#00:00:00 (HH:MM:SS)
DT# 1900-01-00-00:00:00
Structure of Instruction line program
SequenceSmallest part of a instruction line program the sequence consisting of one or more instruction line.
Syntactic of sequence– Started one load instruction (LD, LDN) and
finished one or more result instruction (ST, STN, S, R, JMPC, JMPCN, CALC, CALCN).
– Inside the sequence the type of the variables is the same.
– JMP, CAL, RET are the one line instructions.
Bool algebra
AND
OR
XOR
The relaycoil1 is energised if the contact1 and the contact2 are closed.
The relaycoil2 is energised if the contact1 or contact2 are the closed.
The relaycoil3 is energised if either the contact1 or the contact2 are closed.
Sequence
AND
OR
XOR
LD contact1
AND contact2
ST relaycoil1
LDN contact1
OR contact2
ST relaycoil2
LD contact1
ANDN contact2
LDN contact1
AND contact2
OR
ST relaycoil3
LD contact1
XOR contact2
ST relaycoil3
Circuit connections between ends
Logical closed instruction series
Structure of Ladder diagram
Type
Suggested flowchart of the PLC program
If the result of the conditions is false the actions aren’t processed and begins automatically examination of the next conditions.
The jumped actions aren’t processed. It remains the latest value.
There aren’t conditions before JMP, CAL instructions
Actions
conditions
conditions
conditions
Actions
Actions
Jump’s labelCall’s name
Steps of creating control program • Flowchart of the program
define input, output, and internal variables
• Hardware topology file
• Edit program file and reference filedefinition of variables, edit program, syntax check
• Compile editing programconvert to machine code, error massages
• Transfer (download) to PLC
• Test and commissioning start/stop program running, display program in running
• Modify program