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