Staff Site Universitas Negeri Yogyakarta
SCADA SYSTEM, HARDWARE &
FIRMWARE
SCADA SYSTEM
A system consisting of a number of
remote terminal units (or RTUs)
collecting field data connected back to
a master station via a communications
system.
The master station displays the
acquired data and also allows the
operator to perform remote control
tasks.
On a more complex SCADA system there
are essentially five levels or hierarchies:
• Field level instrumentation and control
devices
• Marshalling terminals and RTUs
• Communications system
• The master station(s)
• The commercial data processing
department computer system
DISTRIBUTED CONTROL SYSTEM (DCS)
The data acquisition and control functions are performed by a
number of distributed microprocessor-based units situated near
to the devices being controlled or the instrument from which
data is being gathered.
PROGRAMMABLE LOGIC CONTROLLER (PLC)
PLCs have replaced hardwired relays with a combination of
ladder–logic software and solid state electronic input and
output modules.
SMART INSTRUMENT
Typically means an intelligent (microprocessor based) digital
measuring sensor (such as a flow meter) with digital data
communications provided to some diagnostic panel or
computer based system.
REMOTE TERMINAL UNITS
a standalone data acquisition and control unit, generally
microprocessor based, which monitors and controls equipment
at some remote location from the central station.
Its primary task is to control and acquire data from process
equipment at the remote location and to transfer this data back
to a central station
The RTU can also act as a relay station (sometimes referred to
as a store and forward station) to another RTU, which may not
be accessible from the central station.
Small sized RTUs generally have less than 10 to 20 analog and
digital signals, medium sized RTUs have 100 digital and 30 to
40 analog inputs.
Typical RTU hardware modules include:
Control processor (or CPU)
This is generally microprocessor based (16 or 32 bit)
e.g. 68302 or 80386. Total memory capacity of 256
kByte (expandable to 4 Mbytes)
Analog input modules
There are five main components making up an analog
input module. They are:
•
•
•
•
•
The
The
The
The
The
input multiplexer
input signal amplifier
sample and hold circuit
A/D converter
bus interface and board timing system
ANALOG I/O MODUL
DIGITAL INPUTS
These are used to indicate items such
as status and alarm signals.
Digital output module
A digital output module drives an output
voltage at each of the appropriate output
channels with three approaches possible:
• Triac switching
• Reed relay switching
• TTL voltage outputs
COMMUNICATION INTERFACES
The modern RTU should be flexible
enough to handle multiple
communication media such as:
•
•
•
•
•
•
RS-232/RS-442/RS-485
Dialup telephone lines/dedicated landlines
Microwave/MUX
Satellite
X.25 packet protocols
Radio via trunked/VHF/UHF/900 MHz
PLCS USED AS RTUS
The advantage of a PLC over the RTU offerings from
various manufacturers is that it can be used in a
general-purpose role and can easily be set up for a
variety of different functions.
PLCs are popular for the following reasons:
Economic solution
Versatility and flexibility
Ease of design and insta
More reliable
Sophisticated control
Physically compact
Easier troubleshooting and diagno
THE MASTER STATION
The central site/master station can be pictured as having one
or more operator stations connected to a communication
system consisting of modem and radio receiver/transmitter.
The features that should be available are:
• Operator interface to display status of the RTUs and enable operator
control
• Logging of the data from the RTUs
• Alarming of data from the RTU
master station has two main functions:
• Obtain field data periodically from RTUs and submaster stations
• Control remote devices through the operator station
The master station has the following typical functions:
Establishment of communications
Operation of the communications link
• Configure each RTU
• Initialize each RTU with input/output parameters
• Download control and data acquisition programs to the RTU
• If a master slave arrangement, poll each RTU for data and write to
RTU
• Log alarms and events to hard disk (and operator display if necessary)
• Link inputs and outputs at different RTUs automatically
Diagnostics
• Provide accurate diagnostic information on failure of RTU and possible
problems
• Predict potential problems such as data overloads
VARIOUS APPROACHES POSSIBLE FOR THE MASTER STATION
It may also be necessary to set up a submaster
station. This is to control sites within a specific
region.
The submaster station has the following
functions:
• Acquire data from RTUs within the region
• Log and display this data on a local operator
station
• Pass data back to the master station
• Pass on control requests from the master station
to the RTUs in its region
COMMUNICATION ARCHITECTURES
Point-to-point (two stations)
Multipoint (or multiple stations)
Relay Stations
Communication philosophies
There are two main communication
philosophies possible. These are; polled (or
masterslave) and carrier sense multiple
access/collision detection (CSMA/CD).
FIRMWARE
SCADA SYSTEM
A system consisting of a number of
remote terminal units (or RTUs)
collecting field data connected back to
a master station via a communications
system.
The master station displays the
acquired data and also allows the
operator to perform remote control
tasks.
On a more complex SCADA system there
are essentially five levels or hierarchies:
• Field level instrumentation and control
devices
• Marshalling terminals and RTUs
• Communications system
• The master station(s)
• The commercial data processing
department computer system
DISTRIBUTED CONTROL SYSTEM (DCS)
The data acquisition and control functions are performed by a
number of distributed microprocessor-based units situated near
to the devices being controlled or the instrument from which
data is being gathered.
PROGRAMMABLE LOGIC CONTROLLER (PLC)
PLCs have replaced hardwired relays with a combination of
ladder–logic software and solid state electronic input and
output modules.
SMART INSTRUMENT
Typically means an intelligent (microprocessor based) digital
measuring sensor (such as a flow meter) with digital data
communications provided to some diagnostic panel or
computer based system.
REMOTE TERMINAL UNITS
a standalone data acquisition and control unit, generally
microprocessor based, which monitors and controls equipment
at some remote location from the central station.
Its primary task is to control and acquire data from process
equipment at the remote location and to transfer this data back
to a central station
The RTU can also act as a relay station (sometimes referred to
as a store and forward station) to another RTU, which may not
be accessible from the central station.
Small sized RTUs generally have less than 10 to 20 analog and
digital signals, medium sized RTUs have 100 digital and 30 to
40 analog inputs.
Typical RTU hardware modules include:
Control processor (or CPU)
This is generally microprocessor based (16 or 32 bit)
e.g. 68302 or 80386. Total memory capacity of 256
kByte (expandable to 4 Mbytes)
Analog input modules
There are five main components making up an analog
input module. They are:
•
•
•
•
•
The
The
The
The
The
input multiplexer
input signal amplifier
sample and hold circuit
A/D converter
bus interface and board timing system
ANALOG I/O MODUL
DIGITAL INPUTS
These are used to indicate items such
as status and alarm signals.
Digital output module
A digital output module drives an output
voltage at each of the appropriate output
channels with three approaches possible:
• Triac switching
• Reed relay switching
• TTL voltage outputs
COMMUNICATION INTERFACES
The modern RTU should be flexible
enough to handle multiple
communication media such as:
•
•
•
•
•
•
RS-232/RS-442/RS-485
Dialup telephone lines/dedicated landlines
Microwave/MUX
Satellite
X.25 packet protocols
Radio via trunked/VHF/UHF/900 MHz
PLCS USED AS RTUS
The advantage of a PLC over the RTU offerings from
various manufacturers is that it can be used in a
general-purpose role and can easily be set up for a
variety of different functions.
PLCs are popular for the following reasons:
Economic solution
Versatility and flexibility
Ease of design and insta
More reliable
Sophisticated control
Physically compact
Easier troubleshooting and diagno
THE MASTER STATION
The central site/master station can be pictured as having one
or more operator stations connected to a communication
system consisting of modem and radio receiver/transmitter.
The features that should be available are:
• Operator interface to display status of the RTUs and enable operator
control
• Logging of the data from the RTUs
• Alarming of data from the RTU
master station has two main functions:
• Obtain field data periodically from RTUs and submaster stations
• Control remote devices through the operator station
The master station has the following typical functions:
Establishment of communications
Operation of the communications link
• Configure each RTU
• Initialize each RTU with input/output parameters
• Download control and data acquisition programs to the RTU
• If a master slave arrangement, poll each RTU for data and write to
RTU
• Log alarms and events to hard disk (and operator display if necessary)
• Link inputs and outputs at different RTUs automatically
Diagnostics
• Provide accurate diagnostic information on failure of RTU and possible
problems
• Predict potential problems such as data overloads
VARIOUS APPROACHES POSSIBLE FOR THE MASTER STATION
It may also be necessary to set up a submaster
station. This is to control sites within a specific
region.
The submaster station has the following
functions:
• Acquire data from RTUs within the region
• Log and display this data on a local operator
station
• Pass data back to the master station
• Pass on control requests from the master station
to the RTUs in its region
COMMUNICATION ARCHITECTURES
Point-to-point (two stations)
Multipoint (or multiple stations)
Relay Stations
Communication philosophies
There are two main communication
philosophies possible. These are; polled (or
masterslave) and carrier sense multiple
access/collision detection (CSMA/CD).