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Industrial Networks
http://truongdinhchau.net
Summary
Introduction to Industrial Communication
Modbus
CANopen
Ethernet Modbus TCP/IP
EtherNet / IP
2
EtherNet / IP
Profibus
Introduction to Industrial
Communication
What is Communication?
4
Smoke signals Telegraph Digital exchange
Why Communication?
Same Radio models (ID)
Transmit by Air
Same Frequency
5
Radio must be Switched on
Same Language
Do not speak in the same time
Acknowledge the message
Items Mandatory to Communicate
Transmitter Receiver
Medium
Language
Translator
Collision
6
Transmitter Receiver
Id = 3
Id = 4
Id = 2
Acknowledgement
Industrial Communication
Serial link
Digital data
01
7
Wired Solution
Analogue speed
command 0-10 V
Communication Solution
Industrial Communication (Cont.)
Diagnostic
8
Easiness of Replacement
OSI Model for Machine Communication
Layer Train Example Machine
Application Same Language? Protocol
Presentation Radio AM or FM? Format Conversion
9
Session Radio ON? History + Organisation
Transport Message Received?End to End Routing
Control
Network Same Frequency? Address
Data Link Who speaks first? Access Control
Physical Air (radio waves) Coverage? Hardware
OSI Model: Encapsulation Principle
Clothes Suitcase Name Tag Dest. tag Airplane
10
Market Requirements
1 s
1
minute
1 Kb
1 Mb Information System
PC - Servers
Level 3Company
Data bus
Level 2Process Production management
Files in N x seconds
11
RESPONSE
TIME
REQUIRED
1 ms
1 s
1 bit
AMOUNT
OF DATA TO BE
TRANSMITTED
Process
Field bus
Production managementPLCs - GUI
Level 1Machines
Device bus
Monitoring and controlVariable speed drives
Automation islands
Reaction detection
Digital actuators sensors
Level 0Components
Sensor busN x bits in N x ms
N x words in N x 10 ms
N x 10 words in N x 100 ms
Positioning of The Main NetworksR
e
s
p
o
n
s
e
t
i
m
e
Machine
CANopen*
Fipio
Sercos,,
Sensor
AS-i*
Interbus S
Process
Fipway
DeviceNet
12
Exchange volume
Management
Fipio
1 bit byte K byte M byte
Profibus FMS
Fipway
Ethernet TCP/IP*
Modbus +
Profibus DP / PA
Modbus*
Choice of a Network
APPLICATION
LAYER 7
Medium access: master-slave, token ring, random access?
Language: Modbus, CANopen?Process data: Client-server, producer-consumercontent, periodicity?
Service data: Accessible variables, max. size?
13
Medium: twisted pair, coaxial cable, optical fibre?
LINK
LAYER
2
1PHYSICAL
LAYER Topology: bus, star, tree, grid?
Max. no. of devices: 2, 31, 63, 127?
Max. distance between devices: 100 m, 1 km, 15 km?
Medium access: master-slave, token ring, random access?
Addressing: address 1, 5, general distribution?
Transmission control: parity check, CRC, delimiters?
Flow control: NACK, XON-XOFF, inhibit time?
Terminology
Half / Full duplex
14
PLC I/OCOLLISION
PLC I/O
TRANSMIT
TRANSMIT
Terminology (Cont.)
Kbps
= Kilobits (1024 bits) per second (binary) but
kbps
= kilobits (1000 bits) per second (decimal)
KBps
15
KBps
= Kilobytes (1024 bytes) per second (binary)
kBps
= kilobytes (1000 bytes) per second (decimal)
Terminology (Cont.)
Differential Signal
16
Terminology (Cont.)
Cyclic Exchange / Implicit Exchange
Process data / high priority
Data exchanged between device periodically on demand.
Managed automatically / defined in configuration
17
Acyclic Exchange / Explicit Exchange
Configuration or diagnostic data / low priority
Data exchanged only on request
Managed by the application / request to be programmed
Medium & Physical Layer
18
Medium & Physical Layer
Cabled link
Fiber optic link
19
Radio links
Common Medium
Coaxial cable
The coaxial cable has excellent electrical
properties and is suitable for high speed
transmission.
Twisted pair(s) wires
Easy to install, and the least expensive.
Optical fiber
Cost of
the
medium
Low
20
The choice of the MEDIUM affects the transmission quality :
Speed
Length of the bus
Electromagnetic immunity
This is suitable for use in harsh industrial
environments. The transmission is reliable over long
distances. High
Examples of Physical Layer
RS232
Half or Full duplex, point-to-point link.
Max. length : 15 m, Max. speed : 20 Kbps
Using example : Connecting a device to a PC
RS422 Full-duplex (simultaneous bidirectional) multi-drop bus on 4
21
Full-duplex (simultaneous bidirectional) multi-drop bus on 4 wires.
Differential signal : good immunity to interference
Max. length : 1000 m at 100 Kbps, Max. speed : 12 Mbit/s
Maximum devices on the bus : 32
Using example : Interbus S fieldbus
RS485
Half-duplex (alternate bidirectional) multi-drop bus on 2 wires.
Same electrical characteristics as RS422A but on 2 wires.
Using example : Modbus, Profibus fieldbus
POINT-TO-POINT
GRIDRING
Example: PC - PLC
console connector link
Example: CANopen,
DeviceNet, Profibus-DP,
FIPIO, Modbus RS485
Various topologies
BUSBypass Chaining
Line termination resistors
22
STAR TREE
GRID
Example : Devices connected over
Ethernet via a HUB
Example: Interbus S Example:
Internet network
via routers
Example:
Intranet network
via hubs and switches
Data Link Layer
23
Master-Slave system
The master grants access to the medium
The slave can access the medium after being polled by the master
Polling
Do you have anything to say?
24
Response
Nothing to declare!
Used by Asi, FIPIO, Modbus, Profibus-DP and Uni-Telway
Can be used on CANopen and DeviceNet (by configuration)
MASTER SLAVE
Token Ring
Ring: the members of a ring are authorized to send data upon receipt of
the token.
Token: a group of bits passed from one node to another in ascending
order of address.
Address 2
25
Address 1 Address 3
Address 4
Used by Modbus Plus / Profibus in Multi Master mode
Data can be transmitted as soon as a silence is detected.
2 types of collision
Each device "listens" whilst it transmits
If the data received is different from the data sent, a collision occurs
Random access
26
2 types of collision
destructive
non-destructive
Random access with destructive collisions
Stop Stop
Waiting time 10sWaiting time 15s
27
Waiting time 5s
Random access with destructive collisions
Step-by-step operation in the event of a collision:
any messages in the course of transmission are stopped
a scrambling frame is sent: the frame is lost
a random wait time is observed
the message is resent
28
Stop
CSMA-CD = Carrier Sense Multiple Access - Collision Detection
Principle used by Ethernet and known as CSMA-CD
Random access with non-destructive
collisions
Stop
Dominant Recessive
29
Dominant Recessive
Dominant Recessive
Random access with non-destructive
collisions
The message remains valid, due to a system of dominant and recessive bits
the device with the lower priority stops its transmission (recessive bit)
the device with the higher priority completes its transmission
the device with the lower priority tries to send its message again as soon
as the medium is free
30
as the medium is free
CSMA-CA = Carrier Sense Multiple Access - Collision Avoidance
Principle used by CANopen and DeviceNet and known as CSMA-CA
StopDominant Recessive
Network, Transport, Session &
Presentation Layers
31
Network & Transport
Network Layer
Defines how to route a message
32
Transport Layer
Responsible for delivery the message
Ethernet Chapter
Session & Presentation
Session Layer
Establish or close a connection remotely
33
Presentation Layer
Present the message on a specific format
Wikipedia
Application Layer
34
Client Server Model
The CLIENT is an entity requesting a service on the network
The SERVER is the entity which responds to a request from a client
Request
35
Response
No problem, here is the whole file!
Please, can you send me the
configuration of motor starter no. 3 ?
SERVERCLIENT
Producer Consumer Model
The PRODUCER is a single entity which produces information.
The CONSUMER is an entity which use it (several entities can use the
same information).
I m going to miss
my train !!!
36
CONSUMER N1
my train !!!
CONSUMER N2
Let s go to see
a movie...
PRODUCER
It s 6 pm
Errors Detection
Undetected Errors Are Disturbing
Many Systems / Algorithms to Detect Errors
Parity bits, CRC checks, stuffing bits, timeouts, ACK slotsI
37
Performance Measurement
Hamming distance