Programmable Logic Controllers - PowerPoint PPT Presentation


Title: Programmable Logic Controllers


1
Programmable Logic Controllers
  • LO1 Understand the design and operational
    characteristics of a PLC system

2
Learning Outcome 1
  • LO1 Understand the design and operational
    characteristics of a PLC system
  • 1.3 evaluate the different types of communication
    link used in programmable logic control systems

3
BehaviouralObjectives
  • At the end of this session the students will be
    able to cables that meet
  • selection criteria, description of features,
    frequency ranges, technology eg analogue,
    digital, wireless cable eg twisted pairs,
    coaxial, fibre-optic, shielded/unshielded,
    categories, operational lengths connector eg
    Bayonet-Neill-Concelman (BNC), registered jack
    (RJ-45), straight tip (ST), universal serial bus
    (USB) type A and type B opto-isolator eg
    photodiode, phototransistor, thyristors, triacs

4
Remote Connections
  • When there are many inputs and outputs located
    considerable distances away from the PLC, though
    it would be possible to run cables from each such
    device to the PLC, a more economic solution is to
    use input / output modules in the vicinity of the
    inputs and outputs and use just a single core
    cable to connect each over the long distances to
    the PLC instead of using the multicore cable that
    would be needed without such I/O modules

5
Remote Connections
Twisted-pair or screened cable, or fibre-optic
cable, communications link
PLC
Input and Output connections
Power cable
Remote input / output module
6
PLC Networks
  • In some situations a number of PLCs may be linked
    together via a master PLC unit sending and
    receiving input / output data from other units

Communications Module
Master PLC
Other I/O Modules
PLC
PLC
Communications Port
7
PLC Networks
  • The distant PLCs do not contain the control
    programme since all the control processing is
    carried out by the master PLC

8
Cables
  • The cables used for communicating data between
    remote input/output modules and a central PLC or
    remote PLC and the master PLC are typically
    twisted-pair cabling, often routed through
    grounded steel conduit to reduce electrical
    noise.

9
Twisted Pair
  • Unshielded Twisted Pair (UTP) cabling is a type
    of wiring in which two conductors of a single
    circuit are twisted together for the purposes of
    cancelling out electromagnetic interference from
    external sources

10
Twisted Pair
  • Twisted pair cabling is often used in data
    networks for short and medium length connections
    because of its relatively lower costs compared to
    optical fibre and coaxial cable.

11
Twisted Pair
  • Shielded twisted pair (STP or STP-A) 
  • Screened twisted pair (ScTP or F/TP) 
  • Screened shielded twisted pair (S/STP or S/FTP) 

12
Twisted Pair
  • Twisted pair cables are often shielded in an
    attempt to prevent electromagnetic interference.
    Because the shielding is made of metal, it may
    also serve as a ground. However, usually a
    shielded or a screened twisted pair cable has a
    special grounding wire added called a drain wire.
  • This shielding can be applied to individual
    pairs, or to the collection of pairs. When
    shielding is applied to the collection of pairs,
    this is referred to as screening.

13
Twisted Pair
  • Shielding provides an electric conductive barrier
    to attenuate electromagnetic waves external to
    the shield and provides conduction path by which
    induced currents can be circulated and returned
    to the source, via ground reference connection.

14
Skin-depth
  • As the frequency of the communicated signal
    increases then less and less of the
    cross-sectional area of the cable is used to
    transmit electricity.
  • At a particular frequency only the surface of the
    conductor actually conducts electricity. Above
    this frequency the cable will not conduct, rather
    it will radiate.

15
Coaxial Cables
  • Co-axial cable enables higher data rates to be
    transmitted and does not require the shielding of
    steel conduit

16
Coaxial Cables
  • Coaxial cable is used as a transmission line for
    radio frequency signals.
  • Its applications include feed-lines connecting
    radio transmitters and receivers with their
    antennas, computer network (internet) connections
    and distributing cable television.
  • Coaxial cable also provides protection of the
    signal from external electromagnetic
    interference.

17
Fibre Optic Cables
  • Fibre-optic cabling has the advantage of
    resistance to noise, small size and flexibility
    and is now becoming now widely used

18
BNC Connectors
  • The BNC connector (Bayonet Neill-Concelman (BNC)
    is a miniature quick connect / disconnect RF
    connector used for coaxial cable
  • It features two bayonet lugs on the female
    connector which mates with a quarter turn of the
    coupling nut to the male connector

19
BNC Connectors
  • BNC connectors normally work with frequencies up
    to 2 GHz and voltages up to 500 v
  • BNC connectors can be used on Ethernet networks
    both on cable interconnections and network cards

20
Registered Jack (RJ-45)
  • A Registered Jack (RJ) is a standarised physical
    network interface standardising both both jack
    construction and wiring pattern for connecting
    telecommunications or data equipment to a service
    provided by local exchange carrier or long
    distance carrier.
  • The physical connectors that Registered Jacks use
    are mainly of the modular connector and 50-pin
    miniature ribbon connector types. For example,
    RJ11 uses a 6P2C (6-position, 2-conductor)
    modular plug and jack.

21
Registered Jack (RJ-45)
22
Registered Jack (RJ-45)
  • Strictly, Registered Jack refers to both the
    female physical connector (modular connector) and
    its wiring, but the term is often used loosely to
    refer to modular connectors regardless of wiring
    or gender, such as in Ethernet over twisted.

23
Straight Tip (ST)Connectors
  • An optical fiber connector terminates the end of
    an optical fibre and enables quicker connection
    and disconnection than splicing.
  • The connectors mechanically couple and align the
    cores of fibres so light can pass. Better
    connectors lose very little light due to
    reflection or misalignment of fibres.
  • In all about 100 fibre optic connectors have been
    introduced to the market.

24
Straight tip (ST) Connectors
25
Universal Serial Bus(USB)
  • Universal Serial Bus (USB) is an industry
    standard developed in mid-1990 that defines the
    cables, connectors and communications protocols
    used in a bus for connection, communication and
    power supply between computers and electronic
    devices

26
Universal Serial Bus(USB) type A and B
27
Universal Serial Bus(USB)
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Programmable Logic Controllers

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Programmable Logic Controllers LO1: Understand the design and operational characteristics of a PLC system Learning Outcome 1 LO1: Understand the design and ... – PowerPoint PPT presentation

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Transcript and Presenter's Notes

Title: Programmable Logic Controllers


1
Programmable Logic Controllers
  • LO1 Understand the design and operational
    characteristics of a PLC system

2
Learning Outcome 1
  • LO1 Understand the design and operational
    characteristics of a PLC system
  • 1.3 evaluate the different types of communication
    link used in programmable logic control systems

3
BehaviouralObjectives
  • At the end of this session the students will be
    able to cables that meet
  • selection criteria, description of features,
    frequency ranges, technology eg analogue,
    digital, wireless cable eg twisted pairs,
    coaxial, fibre-optic, shielded/unshielded,
    categories, operational lengths connector eg
    Bayonet-Neill-Concelman (BNC), registered jack
    (RJ-45), straight tip (ST), universal serial bus
    (USB) type A and type B opto-isolator eg
    photodiode, phototransistor, thyristors, triacs

4
Remote Connections
  • When there are many inputs and outputs located
    considerable distances away from the PLC, though
    it would be possible to run cables from each such
    device to the PLC, a more economic solution is to
    use input / output modules in the vicinity of the
    inputs and outputs and use just a single core
    cable to connect each over the long distances to
    the PLC instead of using the multicore cable that
    would be needed without such I/O modules

5
Remote Connections
Twisted-pair or screened cable, or fibre-optic
cable, communications link
PLC
Input and Output connections
Power cable
Remote input / output module
6
PLC Networks
  • In some situations a number of PLCs may be linked
    together via a master PLC unit sending and
    receiving input / output data from other units

Communications Module
Master PLC
Other I/O Modules
PLC
PLC
Communications Port
7
PLC Networks
  • The distant PLCs do not contain the control
    programme since all the control processing is
    carried out by the master PLC

8
Cables
  • The cables used for communicating data between
    remote input/output modules and a central PLC or
    remote PLC and the master PLC are typically
    twisted-pair cabling, often routed through
    grounded steel conduit to reduce electrical
    noise.

9
Twisted Pair
  • Unshielded Twisted Pair (UTP) cabling is a type
    of wiring in which two conductors of a single
    circuit are twisted together for the purposes of
    cancelling out electromagnetic interference from
    external sources

10
Twisted Pair
  • Twisted pair cabling is often used in data
    networks for short and medium length connections
    because of its relatively lower costs compared to
    optical fibre and coaxial cable.

11
Twisted Pair
  • Shielded twisted pair (STP or STP-A) 
  • Screened twisted pair (ScTP or F/TP) 
  • Screened shielded twisted pair (S/STP or S/FTP) 

12
Twisted Pair
  • Twisted pair cables are often shielded in an
    attempt to prevent electromagnetic interference.
    Because the shielding is made of metal, it may
    also serve as a ground. However, usually a
    shielded or a screened twisted pair cable has a
    special grounding wire added called a drain wire.
  • This shielding can be applied to individual
    pairs, or to the collection of pairs. When
    shielding is applied to the collection of pairs,
    this is referred to as screening.

13
Twisted Pair
  • Shielding provides an electric conductive barrier
    to attenuate electromagnetic waves external to
    the shield and provides conduction path by which
    induced currents can be circulated and returned
    to the source, via ground reference connection.

14
Skin-depth
  • As the frequency of the communicated signal
    increases then less and less of the
    cross-sectional area of the cable is used to
    transmit electricity.
  • At a particular frequency only the surface of the
    conductor actually conducts electricity. Above
    this frequency the cable will not conduct, rather
    it will radiate.

15
Coaxial Cables
  • Co-axial cable enables higher data rates to be
    transmitted and does not require the shielding of
    steel conduit

16
Coaxial Cables
  • Coaxial cable is used as a transmission line for
    radio frequency signals.
  • Its applications include feed-lines connecting
    radio transmitters and receivers with their
    antennas, computer network (internet) connections
    and distributing cable television.
  • Coaxial cable also provides protection of the
    signal from external electromagnetic
    interference.

17
Fibre Optic Cables
  • Fibre-optic cabling has the advantage of
    resistance to noise, small size and flexibility
    and is now becoming now widely used

18
BNC Connectors
  • The BNC connector (Bayonet Neill-Concelman (BNC)
    is a miniature quick connect / disconnect RF
    connector used for coaxial cable
  • It features two bayonet lugs on the female
    connector which mates with a quarter turn of the
    coupling nut to the male connector

19
BNC Connectors
  • BNC connectors normally work with frequencies up
    to 2 GHz and voltages up to 500 v
  • BNC connectors can be used on Ethernet networks
    both on cable interconnections and network cards

20
Registered Jack (RJ-45)
  • A Registered Jack (RJ) is a standarised physical
    network interface standardising both both jack
    construction and wiring pattern for connecting
    telecommunications or data equipment to a service
    provided by local exchange carrier or long
    distance carrier.
  • The physical connectors that Registered Jacks use
    are mainly of the modular connector and 50-pin
    miniature ribbon connector types. For example,
    RJ11 uses a 6P2C (6-position, 2-conductor)
    modular plug and jack.

21
Registered Jack (RJ-45)
22
Registered Jack (RJ-45)
  • Strictly, Registered Jack refers to both the
    female physical connector (modular connector) and
    its wiring, but the term is often used loosely to
    refer to modular connectors regardless of wiring
    or gender, such as in Ethernet over twisted.

23
Straight Tip (ST)Connectors
  • An optical fiber connector terminates the end of
    an optical fibre and enables quicker connection
    and disconnection than splicing.
  • The connectors mechanically couple and align the
    cores of fibres so light can pass. Better
    connectors lose very little light due to
    reflection or misalignment of fibres.
  • In all about 100 fibre optic connectors have been
    introduced to the market.

24
Straight tip (ST) Connectors
25
Universal Serial Bus(USB)
  • Universal Serial Bus (USB) is an industry
    standard developed in mid-1990 that defines the
    cables, connectors and communications protocols
    used in a bus for connection, communication and
    power supply between computers and electronic
    devices

26
Universal Serial Bus(USB) type A and B
27
Universal Serial Bus(USB)
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