Chapter 1 - Repositorio Digital EPN
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Transcript Chapter 1 - Repositorio Digital EPN
INTRODUCTION
Chapter 1
IDC Technologies
Topics
Introduction
Modern Instrumentation and Control
OSI Model
Protocols
Standards
IDC Technologies
Introduction
Transfer of Information From One Point to
Another
Transmitter/Receiver/Link
Serial Links vs Parallel Links
Digital Data vs Analog
Mutual Agreement
IDC Technologies
Historical Background
Telegraph System
Morse Code
Baudot Code
IDC Technologies
Three Themes
Physical Standards
Open Systems Interconnection
Protocols
IDC Technologies
Standards
EIA-232 Interface Standard
EIA-485 Interface Standard
IDC Technologies
A Typical Serial Data
Communications Link
Transmitted Data
Analog Signal
Received Data
RS-232
RS-232
DTE
DCE
Terminal
Modem
IDC Technologies
Communication Link
DCE
DTE
Modem
Terminal
Modern Instrumentation
Distributed Control System (DCS)
All Electronic tightly integrated system
Programmable Logic Controller (PLC)
Came from Relay Equipment
SCADA System
RTU’s and Master Station - radio links
Smart Instrumentation
Intelligent Sensors on comms link
Fieldbuses and Devicenets ( and HART)
IDC Technologies
Distributed Control System
(DCS)
Based Around a Data Highway
Modular Distributed & Integrated
Each Module Performs Specific Dedicated
Task
“Good” on Analog Control
Easy Connection to PLC’s / supervisory
Computer Interfaces
IDC Technologies
PLC
Programmable Logic
Controller
Sequence Control and
Interlocking
On/Off Inputs/outputs
Ladderlogic Type
Programs
IDC Technologies
A Typical PLC System
IDC Technologies
SCADA
Supervisory Control and Data Acquisition
System
RTU’s to Master Station
Radio Links /Landlines
Also term used for SCADA Software
package eg Citect
IDC Technologies
Smart Instrumentation
Microprocessor Based Instrument
Embedded Controllers
Data Communications Capability
RS- 232, RS 485 or Fiber Optic
Ability to Multi-drop With Other
Instruments on Same Highway
Wave of the Future...Eg Fieldbus
IDC Technologies
OSI Model
Developed by the ISO
Universal Framework for Building A
Communications Systems
7 Layer Model
3 Layer Model Very Common for Industry
Missing the 8th Layer
IDC Technologies
Representation of the OSI Model
IDC Technologies
Standards Within A
Communications System
Code - Morse - Hex - ASCII
Physical - 232 - 422 - 485
Protocol - Modbus, Profibus, Hart,
Foundation Fieldbus, Ethernet
Open Systems Interconnection Model
IDC Technologies
Protocols
Rules for Transmission of Data (Packets)
Packet Can Include:
Sync Byte
Destination Address
Source Address
Data
Error Detection
Modbus - Profibus - Canbus - Ethernet - TCP/IP
HDLC - DH+ - HART - DNP3 - Interbus - FTP
IDC Technologies
Basic Structure of an
Information Frame Defined
Sync
Byte
Destination
Address
Source
Address
Data to be
Transmitted
Error Detection
Byte
SYNCHRONIZING BYTE Is Used To Synchronize The Receiver.
DESTINATION ADDRESS Is Where The Packet Is Going.
SOURCE ADDRESS Is Where The Packet Has Come From.
DATA Is The Information Contained In The Packet.
ERROR BYTE Is The Result Of The Error Correction Calculation.
IDC Technologies
Voltage Standards
EIA/RS-232 Interface Standard
Half / Full Duplex - Point to Point
EIA/RS-485 Interface Standard
Half Duplex - Multidrop
IDC Technologies
RS-232
IDC Technologies
Two Wire Multidrop RS-485
1200M (4000 FT)
TERMINATION RESISTORS AT BOTH ENDS ONLY
A
G
A
Rt
B
Rt
B
R
TX
TX
RX
R
A
A
B
B
RX
G
GWG
GWG
A
G
G
B
TX
B
A
R
GWG
- Generator
R
- Receiver
- Circuit ground or
circuit common
TX
RX
G
A
A
RX
R
B
GWG
B
- Protective ground or
frame ground
GWG - Green wire ground or
power system ground
Note: The RS-485 standard documentation
leaves out the invertes for the receiver
IDC Technologies
Fiber Optic Cable
Multimode
Sheath
Cladding
Light Rays
Core
Monomode
IDC Technologies
Light Ray
Modbus Protocol Structure
IDC Technologies
Modbus Plus
Builds on Modbus
Token Passing and deterministic
High Speed - minimum of 1Mbit/s
IDC Technologies
HART Protocol
4 - 20 ma Communications
IDC Technologies
ASI Bus
Idiot Proof
167kbps and fast for digitals
31 slaves and 124 I/O points with 5ms
scan
IDC Technologies
The DeviceNet Model
IDC Technologies
Profibus
Typical Architecture of System
IDC Technologies
Foundation Fieldbus
Newest Fieldbus
H1 standard - 31.25kbit/s
HSE - 100Mbit/s
Three layers plus excellent User Layer
IDC Technologies
Ethernet 10BaseT
MAC = Media Access Control
IDC Technologies
TCP/IP
Internet Protocol (IP)
Transmission Control Protocol (TCP)
Application Layer
Three Layer Model
Derived from Internet
IDC Technologies
Wireless Communications
Antenna
RS-232
Antenna
Radio
Transmitter/
Receiver
Radio
Transmitter/
Receiver
Modem
Modem
RS-232
IDC Technologies