CONCEPTOSBSICOS PARACONTROLADORESPROGRAMABLES

1

Qu es un PLC o Controlador Programable?

CONTROLADOR PROGRAMABLEComputador industrial dedicado que controla elementos de salida basados en el estado de las entradas, y un programa desarrollado por el usuario.Originalmente desarrollados para reemplazar a los relays usados para control discreto.

OUTPUTS

2Originated from a General Motors Specification for a reprogrammable control device that could be used in place of relays.First level products were available in the late sixties.Initial functions were limited to relay replacementBase PLC design has Input terminals for connection to input devices, and Output terminals for connection to output devices.Product development curve has closely paralleled the PC. Initial products were limited and expensive. As semiconductors have evolved features have increased and costs have fallen.Today's PLC are much much more than simple relay replacers being able to perform complex math, and high speed operations. Size has been significantly reduced.Today's MicroLogix costs approx.. as much as 2-3 relays

ELEMENTOS DE ENTRADA

Pulsantes Switches Selectores Sensores de Posicin Sensores de Nivel Sensores Fotoelctricos Sensores de Proximidad Contactos auxiliares de contactores Contactos de Rel Thumbwheel Switches

120 VAC 240 VAC 12 VDC 24 VAC/VDC TTL

3Field input devices provide an electrical signal based on a conditionON, OFF etc..The design of the inputs determines the type of electrical signal that can be used.Different applications, and regions may use different voltages.Larger rack mount PLCs typically support a wider range of input voltagesTTL (5Vdc), 12Vdc, 24Vdc/VAC, 48Vdc, 72Vdc, 120Vac, 220Vac etc...

DISPOSITIVOS DE ENTRADA - SALIDA A UN PLC

ELEMENTOS DE SALIDA

Vlvulas Contactores Solenoides Rels de Control Alarmas Luces

SirenasRels 120 VAC/VDC 240 VAC/VDC 24 VAC/VDC

Triac 120 VAC

MOSFET 24 VDC

4Field output devices are controlled by electricity being switched by the PLC.ON, OFF etc..PLCs Switch electricity, they do not supply electricityThe design of the outputs determines the type of electrical Load that can be used.Different applications may require specialized output designs.Voltage/Current issues includeHigher current - relaysLonger life cycle - solid state (Triacs for AC, MOSFET for DC)Triacs 120Vac applications 1/2 amp maximum loadMOSFET 24Vdc applications 1 amp maximum loadIsolation issues can be crucial for an application. Typically the more isolation provided between output points the better. (The more individual commons the better) This provides customers greater flexibility in wiring and controlling different loads with the same PLC.

PRIMEROS PLCs

PLCS MODERNOS

Dentro de un PLC

CRAisla-mientoAisla-mientoPROCESADORCENTRALMEMORIAprogramadatosAlto VoltajeAltoVoltajeBajo VoltajeAC Power Supply85-264 VAC, 50/60HzCircuitsDC Power SupplyoCOMUNICACIONESInputCircuitsOutput

5Primary components of virtually all PLCs, no matter what size are:Input CircuitryOutput CircuitryCentral ProcessorMemoryCommunications Port(s)Power SupplyPLCs are industrially hardened devices capable of operating in extreme environmentsWide Temp extremes 0-60 CHigh humidityHigh VibrationDirty Electrical PowerHigh Noise (electrical) environments

PROGRAMADOR MANUAL

Los PLC vienen en una variedad de tamaos...MicroTpicamente menos de 32 I/OPequeoTpicamente menos de 128 I/OMedianoTpicamente menos de 1024 I/OGrandeTpicamente ms de 1024 I/O

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Y una variedad de formas/configuraciones

PLC fijos.PLC fijos con expansinModularesDistribuidos

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PLC Fijos

ENTRADASARRANQUEI/I/1SALIDASO/3Fuente de poder, Entradas, Salidas y prtico de comunicaciones estn contenidos en un solo chasis.Los elementos de Entrada y Salida estn cableados individualmente al controlador fijo.

8

PLCs Modulares(Lo ms moderno en Flexibilidad)Componentes Mix N MatchProcesadores, Fuentes de Poder y mdulos de I/O enchufadas en un rack o chasis.Disponible en plataformas pequea, mediana y grande.Flexibilidad de resultados en costos ms altos cuando es comparado con el PLC Fijo. PLCs modulares son basados en rack o sin l.Allen-Bradley SLC-500 y PLC 5 son PLCs modulares

10

PLCs DistribuidosConfiable para cualquier tipo de comunicaciones.Todas las I/O son conectadas al procesador mediante un enlace de datos de Alta Velocidad.Tpicamente se encuentran en PLCs medianos y grandes.Para ciertas aplicaciones este tipo de factor de forma es muy ventajoso.Usualmente tienen un costo mayor para hardware pero mucho menor para la integracin de sistema.

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Cableado de Entradas

Bornerade entrada123456789Elementos de EntradaL1L1L210COMPLCBarrera de aislamiento

15This is an illustration of how inputs are connected to the PLC.Power is connected to one side of the input device.The switched side of the input device is then wired to the PLC inputs.To complete the electrical path, L2 (electrical common) is wired to the PLC input common. This provides the electrical path for current flow, when the switch is closed (continuity) the PLC will detect the input device is on.

Cableado de Salidas

OUT 1Elementos de SalidaL2L2L1OUT 1OUT 2OUT 2OUT 3OUT 3OUT 4OUT 4OUT 5OUT 5OUT 6OUT 6L1PLCBornera desalidaBarrera de Aislamiento

16This is an illustration of how isolated outputs are connected to the PLC.Not all Micro PLCs have isolated outputs, isolated outputs remove any chance that an output device with unique requirements could affect any of the other output devices.Power is connected to:On isolated outputs to one side or terminal of the output terminal pair.On common outputs to the Common terminal associated with a specific group of outputs.The switched side of the output terminal is then wired to the field load.

CIRCUITERIA SALIDASTIPO TRANSISTORTIPO RELAY

Ciclo de Operacin del PLC

Scan de EntradasScan deProgramaScan de SalidasPreparacinPreviaINICIOComunicaciones

17Virtually all PLCs operate using a Scan based operating systemInput ScanInput device status is Read and stored for use during the Program ScanProgram ScanThe program developed for the application is scanned (solved) using the information stored in the input image (input scan)As each rung of the program is scanned and solved, the processor sets the results of each rung in the output image.Output ScanThe information that was set during the program scan is actually written to the outputs (outputs are turned ON or OFF).HousekeepingThe PLC checks and updates internal processes for correct operation, checks and deals with communications, and also makes checks that all internal operations are within specifications.Scan TimeThis entire process (full cycle) is called the processors scan time. Typically this time period ranges from 1 to 2 milleseconds (.001~.002 seconds)

Mando elemental

| |( )OUT 0IN 0OUT 0

Principio de funcionamiento del plc

Conceptos de Lgica de Escalera

| ||/|( )InstruccionesLectura/CondicinInstruccionesEscritura/Control| ||/|( )| ||/|( )| || ||/|( )| |( )| |Inicio (Rung #1)Final (Rung #5)

Conceptos de Lgica de Escalera

Instrucciones InputInstrucciones Output| ||/|( )Continuidad NO LgicaTFF

Construccin de Lgica AND (Y)

SI entrada 4 AND (Y) entrada 5 estn activasENTONCES encienda salida 0Continuidad LgicaTTTOn

15This example now illustrates that the two conditional devices (I/4 and I/5) are ON, because of this the PLC will also turn ON output O/0.This illustrates logical continuity

Construccin de Lgica AND (Y)

SI entrada 4 AND (Y) entrada 5 no estn activasENTONCES desactiva salida 0OffFFF

14To program, the user places commands, or instructions along the line of logical continuity. Depending how the commands are placed, determines the type of logic that will be solved.In this example, two conditional devices are placed in series. This provides the equivalent logic of an AND circuit. Both devices must be ON before the PLC will energize or turn on the output device on that rung.I/4 and I/5 ON, turns on O/0

Construccin de Lgica OR (O)

SI entrada 4 OR (O) entrada 5 estn activasENTONCES encienda salida 0

17In the example only one of the conditional contacts need to be ON for the PLC to turn on O/0.

Construccin de Lgica OR (O)

SI entrada 4 OR (O) entrada 5 estn activasENTONCES encienda salida 0Continuidad LgicaTFOnContinuidad LgicaFTOff

18I/4 OR I/5 will turn on O/0

Construccin Compleja

|/|I/11| |I/10

19One of the best features of RLL programming is its ability to form virtually any type of conditional logic combination to provide the required logic.

Ejemplo de Direccionamiento

L1L2PB1ELEMENTO

PB1

LS1

FS2

SOL6| |( )| || |I:1/1I:1/2O:3/1I:1/3DIRECCINL1L2I:1/1

I:1/2

I:1/3

O:3/1

26As mentioned on the previous slide, we are assuming all field devices are actually using Normally Open devices.The PLC rung on the right is virtually identical to the electrical diagram on the left.RLL was designed to closely represent electrical diagrams. This made it much easier for electricians, engineers and technicians to learn and use PLCs.

De Lgica de Rels a Lgica de Escalera

I:1/1I:1/2O:3/0O:3/1| || |( )I:1/4I:1/3I:1/5B3/0| || |( )| |( )| |I:1/6

29Again, the similarities are virtually identical.The primary enhancement is that if changes are needed, or if other logic or conditions need to be added, its as simple as a few keystrokes on the computer.

Aplicacin Tpica de PLC

Motor Solenoide 1Solenoide 2Solenoide 3Sensor 1Sensor 2Ingrediente AIngrediente B

13Here we have a typical example of an application that a PLC would be ideal for:Digital (on/off) controlsHighly repetitive

Operacin de la Mezcladora(Definiendo las salidas)

Solenoide 1On =Sol 3 apagado y Motor apagado y Sensor 2 apagado, y Auto Switch encendido.Off =Sol 3 encendido o Motor encendido o Sensor 2 encendido.

Solenoide 2On =Sol 3 apagado y Motor apagado y Sensor 2 encendido.Off =Sol 3 encendido o Motor encendido o Sensor 1 encendido

MotorOn = Sensor 1 encendido y Solenoide 2 apagado y Solenoide 1 apagadoOff =Solenoide 3 encendido

Solenoide 3On =Sol 1 apagado y Sol 2 apagado y Motor lleva 30 segundos encendido.Off =Solenoide 3 lleva encendido por 60 segundos.Motor Solenoide 1Solenoide 2Solenoide 3Sensor 1Sensor 2Ingrediente AIngrediente B

14The first item a user must understand/appreciate is what is the sequence of control.This is typically done on a piece of paper by someone who understands and appreciates what needs to occur.Do not hook up the PLC and attempt to write the program without first determining the application on paper.This is a fairly typical process.The way the notes are written on the side of an illustration is a common practice. This makes it easy to visualize and understand. It will also help when the program is debugged.

CORFOPYM1

Ing. Pablo AnguloCORFOPYM2Originated from a General Motors Specification for a reprogrammable control device that could be used in place of relays.First level products were available in the late sixties.Initial functions were limited to relay replacementBase PLC design has Input terminals for connection to input devices, and Output terminals for connection to output devices.Product development curve has closely paralleled the PC. Initial products were limited and expensive. As semiconductors have evolved features have increased and costs have fallen.Today's PLC are much much more than simple relay replacers being able to perform complex math, and high speed operations. Size has been significantly reduced.Today's MicroLogix costs approx.. as much as 2-3 relaysIng. Pablo AnguloCORFOPYM3Field input devices provide an electrical signal based on a conditionON, OFF etc..The design of the inputs determines the type of electrical signal that can be used.Different applications, and regions may use different voltages.Larger rack mount PLCs typically support a wider range of input voltagesTTL (5Vdc), 12Vdc, 24Vdc/VAC, 48Vdc, 72Vdc, 120Vac, 220Vac etc...Ing. Pablo AnguloCORFOPYM4Field output devices are controlled by electricity being switched by the PLC.ON, OFF etc..PLCs Switch electricity, they do not supply electricityThe design of the outputs determines the type of electrical Load that can be used.Different applications may require specialized output designs.Voltage/Current issues includeHigher current - relaysLonger life cycle - solid state (Triacs for AC, MOSFET for DC)Triacs 120Vac applications 1/2 amp maximum loadMOSFET 24Vdc applications 1 amp maximum loadIsolation issues can be crucial for an application. Typically the more isolation provided between output points the better. (The more individual commons the better) This provides customers greater flexibility in wiring and controlling different loads with the same PLC.Ing. Pablo AnguloCORFOPYM5Primary components of virtually all PLCs, no matter what size are:Input CircuitryOutput CircuitryCentral ProcessorMemoryCommunications Port(s)Power SupplyPLCs are industrially hardened devices capable of operating in extreme environmentsWide Temp extremes 0-60 CHigh humidityHigh VibrationDirty Electrical PowerHigh Noise (electrical) environmentsIng. Pablo AnguloCORFOPYM6

Ing. Pablo AnguloCORFOPYM7

Ing. Pablo AnguloCORFOPYM8

Ing. Pablo AnguloCORFOPYM10

Ing. Pablo AnguloCORFOPYM12

Ing. Pablo AnguloCORFOPYM15This is an illustration of how inputs are connected to the PLC.Power is connected to one side of the input device.The switched side of the input device is then wired to the PLC inputs.To complete the electrical path, L2 (electrical common) is wired to the PLC input common. This provides the electrical path for current flow, when the switch is closed (continuity) the PLC will detect the input device is on.Ing. Pablo AnguloCORFOPYM16This is an illustration of how isolated outputs are connected to the PLC.Not all Micro PLCs have isolated outputs, isolated outputs remove any chance that an output device with unique requirements could affect any of the other output devices.Power is connected to:On isolated outputs to one side or terminal of the output terminal pair.On common outputs to the Common terminal associated with a specific group of outputs.The switched side of the output terminal is then wired to the field load.Ing. Pablo AnguloCORFOPYM17Virtually all PLCs operate using a Scan based operating systemInput ScanInput device status is Read and stored for use during the Program ScanProgram ScanThe program developed for the application is scanned (solved) using the information stored in the input image (input scan)As each rung of the program is scanned and solved, the processor sets the results of each rung in the output image.Output ScanThe information that was set during the program scan is actually written to the outputs (outputs are turned ON or OFF).HousekeepingThe PLC checks and updates internal processes for correct operation, checks and deals with communications, and also makes checks that all internal operations are within specifications.Scan TimeThis entire process (full cycle) is called the processors scan time. Typically this time period ranges from 1 to 2 milleseconds (.001~.002 seconds)Ing. Pablo AnguloCORFOPYM

Ing. Pablo AnguloCORFOPYM

Ing. Pablo AnguloCORFOPYM

Ing. Pablo AnguloCORFOPYM15This example now illustrates that the two conditional devices (I/4 and I/5) are ON, because of this the PLC will also turn ON output O/0.This illustrates logical continuityIng. Pablo AnguloCORFOPYM14To program, the user places commands, or instructions along the line of logical continuity. Depending how the commands are placed, determines the type of logic that will be solved.In this example, two conditional devices are placed in series. This provides the equivalent logic of an AND circuit. Both devices must be ON before the PLC will energize or turn on the output device on that rung.I/4 and I/5 ON, turns on O/0Ing. Pablo AnguloCORFOPYM17In the example only one of the conditional contacts need to be ON for the PLC to turn on O/0.Ing. Pablo AnguloCORFOPYM18I/4 OR I/5 will turn on O/0Ing. Pablo AnguloCORFOPYM19One of the best features of RLL programming is its ability to form virtually any type of conditional logic combination to provide the required logic.Ing. Pablo AnguloCORFOPYM26As mentioned on the previous slide, we are assuming all field devices are actually using Normally Open devices.The PLC rung on the right is virtually identical to the electrical diagram on the left.RLL was designed to closely represent electrical diagrams. This made it much easier for electricians, engineers and technicians to learn and use PLCs.Ing. Pablo AnguloCORFOPYM29Again, the similarities are virtually identical.The primary enhancement is that if changes are needed, or if other logic or conditions need to be added, its as simple as a few keystrokes on the computer.Ing. Pablo AnguloCORFOPYM13Here we have a typical example of an application that a PLC would be ideal for:Digital (on/off) controlsHighly repetitiveIng. Pablo AnguloCORFOPYM14The first item a user must understand/appreciate is what is the sequence of control.This is typically done on a piece of paper by someone who understands and appreciates what needs to occur.Do not hook up the PLC and attempt to write the program without first determining the application on paper.This is a fairly typical process.The way the notes are written on the side of an illustration is a common practice. This makes it easy to visualize and understand. It will also help when the program is debugged.Ing. Pablo Angulo